ASME PCC-1 –2022
(Revision of ASME PCC-1 –201 9)
Pressure Boundary
Bolted Flange Joint
Assembly
A N A M E R I C A N N AT I O N A L S TA N D A R D
ASME PCC-1– 2022
(Revision of ASME PCC-1 – 2019)
Pressure Boundary
Bolted Flange Joint
Assembly
AN AMERICAN NATIONAL STANDARD
Two Park Avenue • New York, NY • 1 001 6 USA
Date of Issuance: September 30, 2022
This Standard will be revised when the Society approves the issuance of a new edition.
ASME issues written replies to inquiries concerning interpretations of technical aspects of this Standard. Interpretations are
published on the Committee web page and under http://go.asme.org/InterpsDatabase. Periodically certain actions of the ASME
PCC Committee may be published as Cases. Cases are published on the ASME website under the PCC Committee Page at
http://go.asme.org/PCCcommittee as they are issued.
Errata to codes and standards may be posted on the ASME website under the Committee Pages to provide corrections to
incorrectly published items, or to correct typographical or grammatical errors in codes and standards. Such errata shall be used
on the date posted.
The PCC Committee Page can be found at http://go.asme.org/PCCcommittee. There is an option available to automatically
receive an e-mail notification when errata are posted to a particular code or standard. This option can be found on the
appropriate Committee Page after selecting “Errata ” in the “Publication Information ” section.
ASME is the registered trademark of The American Society of Mechanical Engineers.
This code or standard was developed under procedures accredited as meeting the criteria for American National Standards. The standards
committee that approved the code or standard was balanced to ensure that individuals from competent and concerned interests had an
opportunity to participate. The proposed code or standard was made available for public review and comment, which provided an opportunity
for additional public input from industry, academia, regulatory agencies, and the public-at-large.
ASME does not “approve,” “rate,” or “endorse ” any item, construction, proprietary device, or activity. ASME does not take any position with
respect to the validity of any patent rights asserted in connection with any items mentioned in this document, and does not undertake to
insure anyone utilizing a standard against liability for infringement of any applicable letters patent, nor does ASME assume any such liability.
Users of a code or standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of
such rights, is entirely their own responsibility.
Participation by federal agency representatives or persons affiliated with industry is not to be interpreted as government or industry
endorsement of this code or standard.
ASME accepts responsibility for only those interpretations of this document issued in accordance with the established ASME procedures
and policies, which precludes the issuance of interpretations by individuals.
No part of this document may be reproduced in any form,
in an electronic retrieval system or otherwise,
without the prior written permission of the publisher.
The American Society of Mechanical Engineers
Two Park Avenue, New York, NY 10016-5990
Copyright © 2022 by
THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS
All rights reserved
Printed in U.S.A.
CONTENTS
Foreword
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Committee Roster
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Correspondence With the PCC Committee
Summary of Changes
vii
viii
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ix
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
xi
1
Scope
2
Introduction
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Training and Qualification of Bolted Joint Assembly Personnel
4
Cleaning of Gasket Seating Surfaces of Flanges
1
1
.
2
. . . . . . . . . . . . . . . . . .
2
5
Examination of Flange and Fastener Contact Surfaces
6
Alignment of Flange Joints
7
Installation of Gasket
.
.
.
.
.
. . . . . . . . . . . . .
2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
8
Lubrication
9
Installation of Bolts
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
Tightening Procedure
11
Optional Practices
4
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
12
Joint Pressure and Tightness Testing
13
Records
. . . . . . . . . . . . . . . . . . . . . . . . .
6
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
14
Joint Disassembly
15
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
References
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7
Definitions
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
Mandatory Appendix
I
Nonmandatory Appendices
A
Training and Qualification of Bolted Joint Assembly Personnel
B
Description of Common Terms
C
Recommended Gasket Seating Surface Finish for Various Gasket Types
25
D
Guidelines for Allowable Gasket Seating Surface Flatness and Defect Depth
26
E
Flange Joint Alignment Guidelines
31
F
Joint-Tightening Practices and Patterns
.
.
.
.
.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . .
15
24
. .
34
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
48
G
Single-Stud Replacement
H
Bolt Root and Tensile Stress Areas
. . .
. .
. .
. .
. . . . . .
. .
. .
. .
. . . . . . . . . .
49
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
51
.
. . . . .
. . . . .
. . . . .
I
Interaction During Tightening
J
Optional Practices for Flange Joint Assembly
.
K
Nut Factor Calculation of Target Torque
. .
L
ASME B16.5 Flange Bolting Information
M
Washer Usage Guidance and Purchase Specifications for ThroughHardened Washers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
iii
.
. .
.
.
.
.
.
. . . . .
.
. . . . . .
. . .
. .
. .
52
. .
.
. .
. .
.
. .
. .
.
. .
.
.
56
.
.
.
.
.
.
.
.
.
.
.
58
. . . .
59
.
.
.
.
.
.
N
Definitions, Commentary, and Guidelines on the Reuse of Bolts
. . . . . .
64
O
Assembly Bolt Stress Determination
. .
66
P
Troubleshooting Flange Joint Leakage
Q
Considerations for the Use of Powered Equipment
. . . . . . . . . . . . . . .
93
R
Assembly Records Management
.
.
99
. . . . . . . . . . . . . . . . . . . . . . . . .
5
.
. .
.
. . .
. .
. .
.
. . . .
.
. .
. . .
. .
.
.
. . . . . . . . . . . . . . . . . . . . . . . .
. .
.
. .
. .
.
. .
. .
.
.
.
. .
.
. .
. .
.
82
Figures
8-1
Examples of Lubrication Application
D-2-1
Flange Circumferential Variation Tolerance,
D-2-2
Flange Radial Variation Tolerance,
D-3-1
Flange Surface Damage Assessment: Pits and Dents
D-3-2
Flange Surface Damage Assessment: Scratches and Gouges
D-4-1
RTJ Gasket Seating Surface Assessment
E-2-1
Centerline High/Low
T2
T1
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
. . . . . . . . . . . . . . . . . . . . . . . .
.
.
. .
. .
27
28
.
.
.
.
. .
.
.
29
.
. .
.
.
.
.
29
. . . . . . . . . . . . . . . . . . . . . . .
30
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
E-2-2
Excessive Spacing Gap
E-2-3
Parallelism
.
.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
E-2-4
Rotational Two-Hole
F-6.1.1.2.1-1
Pattern #1 (Star Pattern): 24-Bolt Basic Example
F-6.1.1.2.2-1
Pattern #1 (Star Pattern): 24-Bolt Modified Star Example
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .
. . . . . . . . . .
F-6.1.1.2.2-2
Modified Star Pattern With Multiple Tools
F-6.1.2.1-1
Pattern #2 (Quadrant Pattern): 24-Bolt Examples
.
.
.
F-6.1.2.2-1
Pattern #2 (Quadrant Pattern): 24-Bolt Accelerated Cross Example
F-6.1.3.1-1
Pattern #3 (Circular Pattern): 24-Bolt Example
. . . . . . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
.
.
. .
.
.
.
.
.
.
.
33
38
39
40
41
.
.
.
44
.
.
.
.
.
.
45
.
.
.
.
.
F-6.1.3.2-1
Pattern #3 (Circular Pattern): 24-Bolt Step-by-Step Example
.
46
F-6.1.3.3-1
Pattern #3 (Simultaneous Multibolt Circular Pattern): 24-Bolt Step-byStep Example (Two Tools) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
47
J-5-1
Example of Bolt Grouping for a 48-Bolt Flange
. . . . . . . . . . . . . . . . . .
54
P-4.6.1-1
Tapered-Hub-Type Flange
P-4.6.2-1
Slip-On-Type Flange
.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
87
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
87
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
88
P-4.6.3-1
Lap Joint Flange
Q-4.5-1
24-Bolt, 24-Tool Example
Q-4.5-2
24-Bolt, 50% (12-Tool) Example
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
R-2.2-1
Example Long Assembly Record
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
100
R-2.2-2
Example Short Assembly Record
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
101
R-2.2-3
Example Medium-Length Assembly Record
R-2.2-4
Example Multipart Tear-Off Tag
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
96
97
.
.
102
. . . . . .
.
103
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
16
. .
. . .
. .
.
. .
.
.
.
.
.
. . . . .
.
.
.
.
.
.
.
. . . . . . .
.
.
.
.
.
Tables
A-1.4-1
Training Matrix
A-2.1-1
Training of Fundamentals Curriculum
A-2.2-1
Piping Endorsement Curriculum
. . . . . . . . . . . . . . . . . . . . . . . .
18
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
20
A-2.3-1
Powered-Equipment Endorsement Curriculum
A-2.4-1
Heat Exchanger Endorsement Curriculum
C-1
Recommended Gasket Seating Surface Finish for Various Gasket Types
25
D-2-1M
Flange Seating Face Flatness Tolerances (Metric)
27
iv
.
. .
. . . . . . . . . . . . . . . . . .
. .
.
. .
.
. .
.
.
.
. .
.
. .
.
.
. . . . . . . . . . . . . . . .
21
21
D-2-1
Flange Seating Face Flatness Tolerances (U.S. Customary)
D-3-1M
Allowable Defect Depth vs. Width Across Face (Metric)
.
. . . . . . . . . .
.
.
.
.
.
.
27
28
.
.
.
.
.
.
.
.
28
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
33
D-3-1
Allowable Defect Depth vs. Width Across Face (U.S. Customary)
E-2-1
Common Alignment Tolerances
F-4-1
Example Tightening Practices Based on Service Application
F-6.1.1.1-1
Star and Modified Star Pattern Sequencing
F-6.1.2.1.1-1
Quadrant Pattern Cross Sequence
F-6.1.2.1.2-1
Quadrant Pattern Circular Sequence
H-1M
Bolt Root and Tensile Stress Areas (Metric Threads)
.
.
.
.
.
H-1
Bolt Root and Tensile Stress Areas (Inch Series)
.
.
.
.
.
J-6-1
L-1
ASME B16.5 Flange Bolting Information
M-1.3-1
Recommended Washer Temperature Limits
M-2.4-1
Chemical Requirements
M-2.6.1-1
Dimensional Requirements for Metric Washers
.
.
.
.
.
.
.
.
.
.
.
.
62
M-2.6.1-2
Dimensional Requirements for U.S. Customary Washers
.
.
.
.
.
.
.
.
.
.
.
62
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
35
.
.
.
.
36
. . . . . . . . . . . . . . . . . . . . . . . . . . .
42
. . .
. .
. .
43
.
.
.
.
.
.
.
.
49
.
.
.
.
.
.
.
.
50
Legacy Cross-Pattern Tightening Sequence and Bolt-Numbering System
When Using a Single Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
55
. . . . .
.
. .
.
.
. . . .
.
.
. . . .
.
.
.
.
. .
. .
.
58
. . . . . . . . . . . . . . . . . . . .
59
.
.
. . . . . . . . . .
.
.
.
.
.
.
.
.
.
. . . . . . . . .
.
.
.
.
M-2.6.1-3
Dimensional Tolerances for Metric Washers
M-2.6.1-4
Dimensional Tolerances for U.S. Customary Washers
.
.
.
.
.
.
.
.
.
. . . . . . . . . .
. . . . . . . . . . . . . . . . . . . .
.
.
.
.
.
.
.
.
.
.
.
.
61
63
.
63
M-2.8.2-1
Sampling
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
63
O-3.2-1M
Reference Values (Target Torque Index) for Calculating Target Torque
Values for Low-Alloy Steel Bolting Based on Unit Prestress of 1 MPa
(Root Area) (Metric Series Threads) . . . . . . . . . . . . . . . . . . . . . . .
71
O-3.2-1
Reference Values (Target Torque Index) for Calculating Target Torque
Values for Low-Alloy Steel Bolting Based on Unit Prestress of 1 ksi (Root
Area) (Inch Series Threads) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
72
O-4.1-1M
Pipe Wall Thickness Used for Following Tables (mm)
73
O-4.1-1
Pipe Wall Thickness Used for Following Tables (in.)
. . . . . . . . . . . . . .
73
O-4.1-2M
Bolt Stress Limit for SA-105 Steel Flanges Using Elastic–Plastic FEA (MPa)
74
O-4.1-2
Bolt Stress Limit for SA-105 Steel Flanges Using Elastic–Plastic FEA (ksi)
74
O-4.1-3
Flange Rotation for SA-105 Steel Flanges Loaded to Table O-4.1-2M/Table
O-4.1-2 Bolt Stress Using Elastic–Plastic FEA (deg) . . . . . . . . . . . . .
75
O-4.1-4M
Bolt Stress Limit for SA-105 Steel Flanges Using Elastic Closed Form
Analysis (MPa) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. .
76
O-4.1-4
Bolt Stress Limit for SA-105 Steel Flanges Using Elastic Closed Form
Analysis (ksi) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. .
76
O-4.1-5
Flange Rotation for SA-105 Steel Flanges Loaded to Table O-4.1-4M/Table
O-4.1-4 Bolt Stress Using Elastic Closed Form Analysis (deg) . . . . .
77
O-4.1-6M
Bolt Stress Limit for SA-182 F304 Steel Flanges Using Elastic–Plastic FEA
(MPa) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
78
O-4.1-6
Bolt Stress Limit for SA-182 F304 Steel Flanges Using Elastic–Plastic FEA
(ksi) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
78
O-4.1-7
Flange Rotation for SA-182 F304 Steel Flanges Loaded to Table O-4.1-6M/
Table O-4.1-6 Bolt Stress Using Elastic–Plastic FEA (deg) . . . . . . . .
79
O-4.2-1
Example Bolt Stress for SA-105 Steel Weld-Neck Flanges, SA-193 B7 Steel
Bolts, and Spiral-Wound Gasket With Inner Ring (ksi) . . . . . . . . . .
80
O-4.2-2
Example Assembly Bolt Torque for SA-105 Steel Weld-Neck Flanges,
SA-193 B7 Steel Bolts, and Spiral-Wound Gasket With Inner Ring (ft-lb)
81
v
. . . . . . . . . . . . .
P-5-1
P-5-2
P-5-3
P-5-4
P-5-5
Leak
Leak
Leak
Leak
Leak
During Pressure Test . . . . . . . . . . . . . . . . . . . . . . . . . . .
During Heat-Up or Initial Operation . . . . . . . . . . . . . . . .
Corresponding to Thermal or Pressure Upset . . . . . . . . . .
After Long-Term Operation . . . . . . . . . . . . . . . . . . . . . . .
During Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Form
P-3-1
Sample Flange Joint Leak Report
vi
. . . . .
.
.
.
.
.
. . . . .
. . . . .
. . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
89
90
91
91
92
83
FOREWORD
ASME formed an Ad Hoc Task Group on Post Construction in 1993 in response to an increased need for recognized and
generally accepted engineering standards for the inspection and maintenance of pressure equipment after it has been
placed in service. At the recommendation of this task group, the Board on Pressure Technology Codes and Standards
(BPTCS) formed the Post Construction Committee (PCC) in 1995. The scope of this committee was to develop and
maintain standards addressing common issues and technologies related to post-construction activities and to work
with other consensus committees in the development of separate, product-specific codes and standards addressing
issues encountered after initial construction for equipment and piping covered by Pressure Technology Codes and
Standards. The BPTCS covers nonnuclear boilers, pressure vessels (including heat exchangers), piping and piping components, pipelines, and storage tanks.
The PCC selects standards to be developed based on identified needs and the availability ofvolunteers. The PCC formed
the Subcommittee on Inspection Planning and the Subcommittee on Flaw Evaluation in 1995. In 1998, a task group under
the PCC began preparation of Guidelines for Pressure Boundary Bolted Flange Joint Assembly, and in 1999 the Subcommittee on Repair and Testing was formed. Other topics are under consideration and may be developed into future
guideline documents.
The subcommittees were charged with preparing standards dealing with several aspects of the in-service inspection
and maintenance ofpressure equipment and piping. ASME PCC-1, Pressure Boundary Bolted Flange Joint Assembly, is the
standard for bolted flange joint assemblies. ASME PCC-3, Inspection Planning Using Risk-Based Methods, provides
guidance on the preparation of a risk-based inspection plan. Imperfections found at any stage of assembly, installation,
inspection, operation, or maintenance are then evaluated, when appropriate, using the procedures provided in
API 579-1/ASME FFS-1, Fitness-for-Service. Guidance on repair procedures is provided in the appropriate portion
of ASME PCC-2, Repair of Pressure Equipment and Piping. To provide all stakeholders involved in pressure equipment
with a guide to identify publications related to pressure equipment integrity, ASME PTB-2, Guide to Life Cycle Management of Pressure Equipment Integrity, has been prepared.
None ofthese documents are Codes. They provide recognized and generally accepted good practices that may be used in
conjunction with post-construction codes, such as API 510, API 570, and NBBI NB-23, and with jurisdictional requirements.
This Standard uses the words “shall,” “should,” and “may” as follows:
(a) “Shall” is used to denote a requirement.
(b) “Should” is used to denote a recommendation.
(c) “May” is used to denote permission, which is neither a requirement nor a recommendation.
The first edition of ASME PCC-1 was approved for publication in 2000. The 2010 edition was approved by the American
National Standards Institute (ANSI) as an American National Standard on January 14, 2010. The 2013 edition included
many updates and a major new Appendix A titled “Training and Qualification ofBolted Joint Assembly Personnel” and was
approved by ANSI as an American National Standard on August 12, 2013. The 2019 edition contained a number of
updates. The most notable of these updates were the removal of the reference torque tables (Tables 1M and 1) for
similar tables in Appendix O introducing the Target Torque Index and the insertion of a new Appendix Q titled “Considerations for the Use of Powered Equipment.”ASME PCC-1–2019 was approved by ANSI as an American National Standard
on January 17, 2019.
This 2022 edition is a major revision ofASME PCC-1. Requirements and recommendations have replaced the guidelines
of previous editions. “Guidelines for” has been deleted from the title. The main text and many of the appendices have been
revised in their entirety. ASME PCC-1–2022 was approved by ANSI as an American National Standard on August 18, 2022.
vii
ASME PRESSURE TECHNOLOGY
POST-CONSTRUCTION COMMITTEE
(The following is the roster of the Committee at the time of approval of this Standard.)
STANDARDS COMMITTEE OFFICERS
C. D. Rodery, Chair
B. D. Ray, Vice Chair
S. J. Rossi, Secretary
STANDARDS COMMITTEE PERSONNEL
M. Boring, DNV GL
W. Brown, Integrity Engineering Solutions
S. Hamilton, Hex Technology
B. F. Hantz, Valero Energy Corp.
D. M. King, Furmanite America, Inc.
D. E. Lay, D&S Lay, Inc.
D. T. Peters, Structural Integrity Associates
B. D. Ray, Marathon Petroleum Corp.
J. T. Reynolds, Intertek/Moody
S. C. Roberts, Shell Global Solutions US, Inc.
C. D. Rodery, C&S Technology, LLC
S. J. Rossi, The American Society of Mechanical Engineers
I. Roux, Roux Engineering
C. W. Rowley, The Wesley Corp.
J. Taagepera, Chevron Technical Center
G. M. Tanner, M&M Engineering Associates
K. Oyamada, Delegate, High Pressure Gas Safety Institute of Japan
T. Tahara, Delegate, T&T Technology
C. D. Cowfer, Contributing Member, Consultant
N. Faransso, Contributing Member, Faransso NDT Services
K. Mokhtarian, Contributing Member, K. Mokhtarian Consulting, LLC
J. R. Sims, Contributing Member, Becht Engineering Co., Inc.
SUBCOMMITTEE ON FLANGE JOINT ASSEMBLY
S. Hamilton, Chair, Hex Technology
C. D. Rodery, Vice Chair, C&S Technology, LLC
C. Cary, Secretary, Consultant
B. J. Barron, Newport News Shipbuilding
W. Brown, Consultant
M. Bush, Marathon Petroleum Corp.
L. Carpenter, BP
B. F. Hantz, Valero Energy Corp.
D. E. Lay, D&S Lay, Inc.
G. Milne, Flexitallic, Ltd.
M. Ruffin, Chevron Energy Technology Co.
K. Schupp, Methanex Corp.
B. A. Thibodeaux, Citgo Petroleum Corp.
D. Arnett, Contributing Member, ExxonMobil Research and
Engineering
B. Baird, Contributing Member, TEAM, Inc.
J. Barnard, Contributing Member, Hydratight, Ltd.
M. F. Dolan, Contributing Member, HYTORC Corp.
M. Johnson, Contributing Member, Integra Services Technologies, Inc.
J. R. Payne, Contributing Member, JPAC, Inc.
A. Seijas, Contributing Member, Phillips 66 Co.
J. Waterland, Contributing Member, VSP Technologies
J. E. Batey, Honorary Member, Consultant
viii
CORRESPONDENCE WITH THE PCC COMMITTEE
General. ASME Standards are developed and maintained with the intent to represent the consensus of concerned
interests. As such, users of this Standard may interact with the Committee by requesting interpretations, proposing
revisions or a case, and attending Committee meetings. Correspondence should be addressed to:
Secretary, PCC Standards Committee
The American Society of Mechanical Engineers
Two Park Avenue
New York, NY 10016-5990
http://go.asme.org/Inquiry
Proposing Revisions. Revisions are made periodically to the Standard to incorporate changes that appear necessary
or desirable, as demonstrated by the experience gained from the application of the Standard. Approved revisions will be
published periodically.
The Committee welcomes proposals for revisions to this Standard. Such proposals should be as specific as possible,
citing the paragraph number(s) , the proposed wording, and a detailed description of the reasons for the proposal,
including any pertinent documentation.
Proposing a Case. Cases may be issued to provide alternative rules when justified, to permit early implementation of
an approved revision when the need is urgent, or to provide rules not covered by existing provisions. Cases are effective
immediately upon ASME approval and shall be posted on the ASME Committee web page.
Requests for Cases shall provide a Statement of Need and Background Information. The request should identify the
Standard and the paragraph, figure, or table number(s), and be written as a Question and Reply in the same format as
existing Cases. Requests for Cases should also indicate the applicable edition(s) of the Standard to which the proposed
Case applies.
Interpretations. Upon request, the PCC Standards Committee will render an interpretation of any requirement of the
Standard. Interpretations can only be rendered in response to a written request sent to the Secretary ofthe PCC Standards
Committee.
Requests for interpretation should preferably be submitted through the online Interpretation Submittal Form. The
form is accessible at http://go.asme.org/InterpretationRequest. Upon submittal of the form, the Inquirer will receive an
automatic e-mail confirming receipt.
If the Inquirer is unable to use the online form, he/she may mail the request to the Secretary of the PCC Standards
Committee at the above address. The request for an interpretation should be clear and unambiguous. It is further recommended that the Inquirer submit his/her request in the following format:
Subject:
Cite the applicable paragraph number(s) and the topic of the inquiry in one or two words.
Edition:
Cite the applicable edition of the Standard for which the interpretation is being requested.
Question:
Phrase the question as a request for an interpretation of a specific requirement suitable for
general understanding and use, not as a request for an approval of a proprietary design or
situation. Please provide a condensed and precise question, composed in such a way that a
“yes” or “no” reply is acceptable.
Proposed Reply(ies):
Provide a proposed reply(ies) in the form of “Yes” or “No,” with explanation as needed. If
entering replies to more than one question, please number the questions and replies.
Background Information:
Provide the Committee with any background information that will assist the Committee in
understanding the inquiry. The Inquirer may also include any plans or drawings that are
necessary to explain the question; however, they should not contain proprietary names or
information.
ix
Requests that are not in the format described above may be rewritten in the appropriate format by the Committee prior
to being answered, which may inadvertently change the intent of the original request.
Moreover, ASME does not act as a consultant for specific engineering problems or for the general application or
understanding of the Standard requirements. If, based on the inquiry information submitted, it is the opinion of
the Committee that the Inquirer should seek assistance, the inquiry will be returned with the recommendation
that such assistance be obtained.
ASME procedures provide for reconsideration of any interpretation when or if additional information that might affect
an interpretation is available. Further, persons aggrieved by an interpretation may appeal to the cognizant ASME
Committee or Subcommittee. ASME does not “approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary
device, or activity.
Attending Committee Meetings. The PCC Standards Committee regularly holds meetings and/or telephone conferences that are open to the public. Persons wishing to attend any meeting and/or telephone conference should contact the
Secretary of the PCC Standards Committee.
x
ASME PCC-1– 2022
SUMMARY OF CHANGES
Following approval by the ASME PCC Committee and ASME, and after public review, ASME PCC-1–2022 was approved by
the American National Standards Institute on August 18, 2022.
In ASME PCC-1–2022, “Guidelines for” has been deleted from the title. The main text has been revised in its entirety.
Appendices A through Q have been redesignated as “Nonmandatory.” All figures, tables, and forms have been redesignated based on their parent paragraph. Cross-references have been updated. In addition, ASME PCC-1–2022 includes
the following changes, identified by a margin note, (22) .
Page
Location
Change
10
Mandatory Appendix I
Added
15
Nonmandatory Appendix A
Revised in its entirety
24
Nonmandatory Appendix B
Definitions moved to Mandatory Appendix I
25
Nonmandatory Appendix C
(1) “Contact surface” revised to “seating surface” throughout
(2) In Table C-1, “Gasket Seating Surface Finish” column
editorially revised
26
Nonmandatory Appendix D
(1) Title revised
(2) Sections D-1 through D-3 revised
31
Nonmandatory Appendix E
Revised in its entirety
34
Nonmandatory Appendix F
Revised in its entirety
48
Nonmandatory Appendix G
Revised in its entirety
49
Table H-1M
Note (2) revised
51
Nonmandatory Appendix I
Deleted
52
Nonmandatory Appendix J
Revised in its entirety
56
Nonmandatory Appendix K
Revised in its entirety
59
M-1.1
Last paragraph revised
61
M-2.10
Added and former para. M-2.10 redesignated as M-2.11
64
N-1
Revised
65
N-4
Added
66
O-1.1
Revised
66
O-1.3
Definitions of GI.D. and GO.D. revised
67
O-2
Subparagraphs (b) through (d) revised
67
O-3.1
First sentence revised
67
O-3.2
Second and third paragraphs and eq. (O-3) revised
68
O-4.1
Revised
68
O-4.2
First paragraph and footnotes revised
69
O-4.3
Revised
69
O-5.1
Revised
71
Table O-3.2-1M
In General Note (b), cross-reference revised
72
Table O-3.2-1
In General Note (b), cross-reference revised
82
Nonmandatory Appendix P
Revised in its entirety
xi
Page
Location
Change
96
Q-5
Added and former section Q-5 redesignated as Q-6
99
Nonmandatory Appendix R
Added
xii
ASME PCC-1–2022
PRESSURE BOUNDARY BOLTED FLANGE JOINT ASSEMBLY
1 SCOPE
features contained herein that are deemed suitable to
the specific application under consideration. Alternative
features and methods for specific applications may be
used subject to endorsement by the owner.
(b) User. The user is defined as any entity that applies
the provisions of this Standard. The user could be the
owner, owner’s representative, manufacturer, fabricator,
erector, or other contract personnel. The specific assignment ofresponsibilities among these entities is outside the
scope of this Standard. As a result, this Standard is silent
when assigning specific provisions to a single entity.
(c) Ownerand Representative. Within the context ofthis
Standard, “owner” and “representative” are defined as
follows:
This Standard covering bolted flange joint assemblies
(BFJAs) applies to pressure-boundary flange joints with
ring-type gaskets that are entirely within the circle
enclosed by the bolt holes and with no contact outside
this circle. 1 The principles of this Standard may be selectively applied to other joint geometries. By selecting those
features suitable to the specific service or need, this Standard may be used to develop effective j oint assembly
procedures for the broad range of sizes and service conditions normally encountered in industry.
Users [see para. 2(b) ] of this Standard are cautioned
that the content contained in ASME PCC-1 has been developed generically and may not necessarily be suitable for all
applications. Precautionary considerations are provided
in some cases but should not be considered as all-inclusive. Sound engineering judgment and practices should be
used to determine the applicability of a specific method or
part of a method to a specific application. Each j oint
assembly procedure should be subject to an appropriate
review by qualified personnel. While this Standard covers
joint assembly within the scope of ASME Pressure Technology Codes and Standards, it may be used on equipment
constructed in accordance with other codes and standards.
Guidance on troubleshooting BFJAs not providing leaktight performance is also provided in this Standard (see
Nonmandatory Appendix P).
owner: the person, partnership, organization, or business
responsible for the leak tightness of BFJAs on their pressure equipment.
representative:
a person, partnership, organization, or
business designated by the owner to carry out selected
responsibilities on the owner’s behalf.
(d) Responsibilities
(1) Owner. The owner is responsible for establishing
the requirements for assembly, examination, inspection,
and testing of BFJAs on their pressure equipment. The
o wner may designate a rep resentative to carry out
selected responsibilities in establishing such requirements; however, the owner retains ultimate responsibility
for the actions of the representative.
NOTE: Within the context of this Standard, the term “owner”
includes the owner and the owner’s representative, as recorded
in either the contract documents or the written assembly procedures [see para. 13(a) ] .
2 INTRODUCTION
(a) Intent. A BFJA is a complex mechanical device;
therefore, BFJAs that provide leak-free service result
from many selections and activities having been made
and performed within a relatively narrow band of acceptable limits. One of the activities essential to leak-free
performance is the joint assembly process. The content
outlined in this Standard covers the assembly elements
essential for a high level of leak-tightness integrity of
otherwise properly designed and constructed BFJAs.
Users should develop written assembly p rocedures
based on the owner’s requirements, incorporating the
(2) Assembler. Th e as s e mb l e r (s e e M andato ry
Appendix I) of piping, pipelines, or equipment containing
B FJAs is responsible for providing workmanship in
conformance to the requirements of the assembly procedure.
(e) Organization ofThis Standard. The main body ofthis
Standard covers the following topic areas associated with
the BFJA assembly process:
(1) scope and introduction
(2) tra i n i n g a n d q u a l i fi c a ti o n o f b o l te d j o i n t
assembly personnel
(3) cleaning of gasket seating surfaces of flanges
1
Rules for the design of bolted flanges with ring-type gaskets are
covered in ASME B oiler and Pressure Vessel Code (ASME BPVC) ,
Section VIII, Division 1, Mandatory Appendix 2. See also ASME BPVC,
Section VIII, Division 1, Nonmandatory Appendix S for supplementary
considerations for bolted flanges that are helpful to the designer of
Mandatory Appendix 2 flanges.
1
ASME PCC-1–2022
(4) examination of flange and fastener s eating
surfaces (including flange surface finish and flatness,
fastener contact surfaces, and the washers’ bearing
surfaces)
(5) alignment of flange joints
(6) installation of gasket
(7) lubrication
(8) installation of bolts
(9) tightening procedure
(1 0) optional practices
(1 1 ) joint pressure and tightness testing
(1 2) records
(1 3) joint disassembly
(f) Use of “Approved Disposition.” When used in this
Standard, the phrase “approved disposition” refers to a
decision on actions to address a nonconforming condition,
specified by the person having authority (typically the
owner or the owner’s representative).
(g) Use of “Approved.” The term “approved” refers to a
selection made by the owner or the owner’s representative as being suitable for the application under consideration.
Where the phrases in (f) and (g) are used, they will
generally be accompanied by the relevant references
from which additional guidance may be obtained.
(a) Remove all debris and residual material from the
previous gasket installation from the gasket seating
surfaces.
3 TRAINING AND QUALIFICATION OF BOLTED
JOINT ASSEMBLY PERSONNEL
NOTE: If machining or weld repair of imperfections is required
[see (a)(2)] , see ASME PCC-2, Article 305 for repair considerations.
Employers of bolted joint assembly personnel have the
responsibility to provide, or arrange to have provided, an
appropriate training and qualification program in accordance with Nonmandatory Appendix A. If alternative solutions that meet the intent of this Standard are used, they
s hal l b e p ro p e rl y j us ti fie d and do cume nted i n the
employer’s training and qualification program.
The technical classifications and topic of understanding
for each classification are included in Nonmandatory
Appendix A. These classifications and topics are intended
to identify and give names to the skill sets normally associated with the various levels of work required by assemblers.
Assigning titles to these industry-wide skill sets standardizes expectations of competency for users, contractors, labor suppliers, unions, assembly personnel, and
third parties. These titles also represent specific training
objectives.
(b) The following instructions should be included in the
assembly procedure:
(1 ) Examine the gasket seating surfaces of both
mati ng fl ange s fo r co nfo rmance to th e acce p tab l e
surface-finish criteria and damage such as scratches,
nicks, gouges, and burrs.
(2) Report any nonconforming imperfections for
approved disposition.
NOTE: If the replacement gasket is a flexible graphite-clad gasket
or a spiral-wound gasket with flexible graphite filler, residual
flexible graphite from the previous gasket may remain in the
surface-finish grooves.
(b) Avoid surface contamination and damage to the
existing surface finish.
(1 ) Use approved solvents and soft wire brushes.
(2) Do not use carbon steel brushes on stainless steel
flanges.
5 EXAMINATION OF FLANGE AND FASTENER
CONTACT SURFACES
5.1 Examination of Gasket Seating Surfaces for
Surface Finish
(a) Site assembly guidance should specify
(1 ) acceptable gasket contact surface finish based on
the gasket type (see Nonmandatory Appendix C)
(2) accep table limits o n gasket seating surface
imperfections and their locations (see Nonmandatory
Appendix D, sections D-3 and D-4)
NOTES:
(1) Indications running radially across the facing are of particular concern.
(2) It is recommended that surface finish comparator gauges be
available to joint assembly personnel.
5.2 Examination of Gasket Seating Surfaces for
Flatness
(a) Site assembly guidance should specify
(1 ) whether measurement of flange gasket seating
surfaces for flatness is required
4 CLEANING OF GASKET SEATING SURFACES OF
FLANGES
NOTE: A flatness check is typically specified when working with
large-diameter, problematic, or critical service flanges with a
history of leakage or suspect fabrication.
The following instructions should be included in the
assembly procedure:
(2) the acceptable flatness limits for the flange gasket
seating surface, if a flatness check is specified (see
Nonmandatory Appendix D, section D-2)
2
ASME PCC-1–2022
(3) acceptable methods of flatness check, if required
(1 ) E xamine nut or washer bearing surfaces of
fl anges fo r exces s i ve co ati ng, s co re s , b urrs , vis ual
evidence of out-of-squareness (indicated by uneven
wear), etc.
NOTES:
(1) Methods of flatness checks include the use of a machinist’s
straight edge and feeler gauges, a securely mounted flatness
(“run-out”) gauge, and laser or field machining equipment
capable of providing accurate total indicator readings.
(2) If machining or weld repair of imperfections is required, see
ASME PCC-2, Article 305 for repair considerations.
NOTE: Excessive coating is defined as thickness on the flange nut
or washer bearing surface thicker than 0.13 mm (0.005 in.) or
130 μm (5 mils).
(2) Remove roughness, gouges, and protrusions.
(3) Report severely damaged flanges or excessive
coating for approved disposition.
(b) If the measurement of the gasket seating surfaces
for flatness is required [see (a)(1)] , the following instructions should be included in the assembly procedure:
(1 ) C heck gasket seating surfaces of both j oint
flanges for flatness, both radially and circumferentially,
using an approved method.
(2) Report any nonconforming flatness measurements for approved disposition.
6 ALIGNMENT OF FLANGE JOINTS
(a) Site assembly guidance should specify
(1 ) the sequence of the alignment procedure and any
checks, measurements, or verifications to be done during
the alignment process (see Nonmandatory Appendix E,
section E-1)
(2) the verification methods, limits to corrective
loads, and tolerances (see Nonmandatory Appendix E,
section E-2)
(3) the acceptable methods and tools to achieve
alignment (see Nonmandatory Appendix E, section E-3)
(4) the criteria for defining when an engineering
evaluation is necessary (see Nonmandatory Appendix
E, section E-4)
(5) whether there is a requirement to measure and
record initial joint alignment
(6) whether there is a requirement to measure and
record final joint alignment (see Nonmandatory Appendix
J, section J-2)
5.3 Examination of Fastener Contact Surfaces and
Washers
(a) Site assembly guidance should specify the criteria
for replacement or repair of bolts and washers (see
Nonmandatory Appendix N).
NOTES:
(1) Nonmandatory Appendix M provides a through-hardened
washer specification guideline.
(2) If tapped holes require repair, an approved method shall be
used; see ASME PCC-2, Article 303.
(b) The following instructions should be included in the
assembly procedure:
(1 ) Examine bolt and nut threads and washer faces of
nuts for damage such as rust, corrosion, and burrs.
(2) Verify that each nut turns freely by hand past the
location on the bolt where it will come to rest after tightening.
(3) If the bolted joint assembly includes tapped hole
threads, verify that the bolts thread by hand to the full
depth of the tapped holes.
(4) Replace or correct any damaged or nonconforming components.
NOTE: Correct alignment of all joint components is a critical and
essential element of flange joint assembly. It results in maximum
sealing surface contact and maximum opportunity for uniform
and optimum gasket loading, and it reduces frictional variation of
fasteners.
(b) The following instructions should be included in the
assembly procedure:
(1 ) As s e s s th e fl ange al i gnme nt duri ng i ni ti al
assembly.
(2 ) As s e s s th e fl a n ge a l i gn m e n t d u ri n g fi n a l
assembly, if required.
(3) Report misalignment of j oints that cannot be
rectified using acceptable levels of load for approved
disposition.
5.4 Examination of Flange Nut or Washer Bearing
Surfaces
(a) Site assembly guidance should specify
(1 ) whether through-hardened, flat washers are
required to provide a smooth and square nut bearing
surface
(2) any critical joints (see Mandatory Appendix I) for
which removal of coating from flange nut or washer
bearing surfaces is required [see (b)(3)]
(b) The following instructions should be included in the
assembly procedure:
7 INSTALLATION OF GASKET
(a) Site assembly guidance should specify the approved
methods of ensuring the gasket remains in place during
assembly and the acceptable adhesive, ifused, for securing
the gasket in place during the assembly process.
NOTE: A very light dusting of an approved spray adhesive may be
used for this purpose. When selecting an adhesive, avoid adhesive chemistry that is incompatible with the process fluid or that
could result in stress corrosion cracking or pitting of the flange
surfaces.
3
ASME PCC-1–2022
(4) Apply the lubricant from the end of the stud to
extend past the location where the nut face will rest after
tightening.
(5) Do not apply lubricant on the gasket or gasket
seating surfaces.
(b) The following instructions should be included in the
assembly procedure:
(1 ) Examine the new gasket for damage or defects.
(2) Verify the gas ket co nfo rms to dimens io nal
[outside diameter (O.D), inside diameter (I.D.), thickness]
and material specifications.
(3) Position the gasket to be concentric with the
flange I.D. such that the gasket is supported during the
positioning process.
(4) Verify that no portion of the gasket sealing face
projects into the flow path.
(5) For gaskets designed to fit inside a recessed
fl an ge face , ve ri fy th at th e gas ke t fi ts co m p l e te l y
withi n the re ce s s , i . e. , the gas ket do es no t p ro j ect
beyond the O.D. of the recess.
(6) Secure the gasket in place using an approved
method.
(7) Ensure the gasket will remain in place during the
joint assembly process.
(8) Do not apply adhesive tape or other materials
across the gasket sealing face.
(9) Do not apply grease or sealing paste on the gasket
or flange.
9 INSTALLATION OF BOLTS
(a) To support the assembly procedure, determine the
minimum adequate length of bolts.
(1 ) Bolt length should accommodate washers, nut
height, and the required thread protrusion.
(2) For assemblies involving bolt tensioning, the bolt
length should provide for the threaded portion of the bolt
to extend at least one bolt diameter beyond the outside nut
face on the tensioner side of the joint.
CAUTION: Avoid excessively long bolts. Excessive thread
protrusion can complicate joint disassembly due to corrosion, paint, or damage on the exposed thread.
(b) The following instructions should be included in the
assembly procedure:
(1 ) Verify that the bolts, nuts, and washers conform
to required sp ecifications [material grade, nominal
diameter, thread pitch, and nut thickness (heavy hex
versus regular hex)] .
(2) Verify that the bolts are the specified length.
(3) Install the bolts such that the marked ends are on
the same side of the joint. Install nuts with the identification marking facing outward. This practice facilitates
inspection.
(4) I nstall the nut on one end of the stud with
minimal thread protrusion such that any excess thread
length is located on the opposite end ofthe stud. This practice facilitates joint disassembly (see section 14).
(5) Hand tighten the nuts. Then snug up the bolts to
15 N∙m to 30 N∙m (10 ft-lb to 20 ft-lb) but not to exceed
1 0 % o f th e to ta l ta r ge t a s s e m b l y b o l t l o a d ( s e e
Nonmandatory Appendix O).
(6) Examine the bolts for adequate thread protrusion. The criterion in the new construction codes 2 is
th re a d e n ga ge m e n t fo r th e fu l l d e p th o f th e n u t.
However, it has been shown that the full strength in a
threaded fas tener can b e develo p ed with les s than
c o m p l e te th re a d e n ga ge m e n t, a c o n s i d e ra ti o n i n
certain p o s t- co ns truction s ituations (e. g. , s ee p ara.
15.13 and para. 15.15, refs. [4] –[6] ).
8 LUBRICATION
(a) Site assembly guidance should specify an approved
lubricant that is chemically compatible with the process
fluid and the fas tener s ys tem materials (nut, s tud,
washer).
NOTE: Improper lubrication selection could contribute to undesirable outcomes such as stress corrosion cracking, galvanic
corrosion, or autoignition in oxygen service.
(b) The following instructions should be included in the
assembly procedure:
(1 ) Apply lubricant irrespective of the tightening
method used.
(2 ) Ap p l y l u b ri ca n t to wo rki n g s u rfa ce s (s e e
Mandatory Appendix I ) of the fastener system (nut,
stud, washer).
NOTE: Application oflubricant after stud insertion minimizes the
likelihood of contamination with foreign particles such as rust,
paint scale, sand, coke fines, or similar abrasive particles that
could negatively affect the overall nut factor.
(3) Apply lubricant liberally by completely filling the
threads from root to crest on both ends of the studs.
Figure 8-1 illustrates the proper application oflubrication.
10 TIGHTENING PROCEDURE
NOTES:
(1) The liberal application oflubrication will result in the formation of a bead of excess lubricant visible on the nut contact
face as the nut runs down the stud. This bead of lubricant is
visible evidence of an adequate amount of lubricant application.
(2) A consistent amount and extent of application for each bolt
in a flange promotes a consistent nut factor and helps
achieve a consistent bolt load.
(a) The site assembly guidance should include the
following:
(1 ) acceptable tightening method and load-control
techniques , e. g. , hand wrenches , hand- o p erated o r
powered tools with torque measurement, tensioning
2
ASME BPVC, Section VIII, Division 1, Part UG, UG-13 details thread
engagement criteria.
4
ASME PCC-1–2022
Figure 8-1
Examples of Lubrication Application
(a)
In su ffi cien t Lubri cati on : Lack of Fil l
(b) Correct Appl i cati on of Lu brication :
Between Root an d Crest of Th reads
Com pl ete Fil l Pl u s Som e Excess
Note the
uniform bead
of lubricant
around the
entire nut
circumference
after the nut is
run down onto
the flange or
washer.
(c)
I nsu ffi cient Appl ication : I ncom pl ete Extrusi on
(d)
of Lu bri can t Bead
Correct Appl i cati on : Com pl ete Extru si on
of Lu bricant Bead
GENERAL NOTE: Images reprinted with permission from Integrity Engineering Solutions, Dunsborough, Western Australia.
tools with force measurement, or any tightening method
used with bolt elongation or load-control measurement
(2) acceptable tightening patterns (see Nonmandatory Appendix F), including
(-a) single- or multitool usage
(-b) tightening sequence, including consideration
of bolt grouping for flanges containing 48 or more bolts
(see Nonmandatory Appendix J, section J-5)
(-c) guidance on the number ofpasses and the load
increments for each pass
(-d) whether gap measurements are required
b e twe e n p a s s e s ( s e e N o n m a n d a to r y Ap p e n d i x J ,
section J-2)
(-e) whether an additional pass is required based
on the use of a soft (versus hard) gasket
(3) the assembly bolt stress or assembly target
to rque or bo lt lo ad, as ap p licable to the tightening
method (see Nonmandatory Appendix O)
(b) The selections from (a) should be included as the
instructions in the assembly procedure.
11 OPTIONAL PRACTICES
Nonmandatory Appendix J provides the following
optional practices that may be included in the assembly
procedure:
(a) measurement of gaps (see section J-2)
(b) bolt elongation (bolt stretch) measurement (see
section J-3)
(c) start-up retorque (see section J-4)
(d) grouped bolting for large flanges (see section J-5)
5
ASME PCC-1–2022
(e) a l te rn a ti ve l e ga c y c ro s s - p a tte rn ti gh te n i n g
sequence and bolt-numbering system (see section J-6
and Table J-6-1)
(f) controlled disassembly (see section J-7)
(7) disassembly method
(8) leak history
(9) bolts, nuts, and washers used
(1 0) fl atne s s me as ure m e nts , wh e n mad e (s e e
Nonmandatory Appendix D)
(1 1 ) assembly procedure and tightening method
used, including applicable target prestress values in accordance with the indicated tightening method
(1 2) unanticipated problems and their solutions
during assembly or disassembly (tool access or safety
issues, presence of nut seizing or thread galling, unanticipated pipe cold spring, etc.)
(1 3) tool data such as type, model, pressure setting,
and calibration identification
(1 4) recommendations for future assembly procedures and joint maintenance and repairs
See Nonmandatory Appendix R for examples of joint
as s emb ly re co rds . S e e N o nmandato ry Ap p e ndi x P ,
Form P-3-1 for an example of a joint leakage record.
12 JOINT PRESSURE AND TIGHTNESS TESTING
Specification of the requirements for joint pressure and
tightness testing is often influenced by an applicable code
or standard or by jurisdictional requirements. This testing
is typically performed according to site maintenance and
operating procedures, rather than being included in the
scope of the flange assembly procedure.
NOTE: Refer to ASME PCC-2, Article 501 for general practices for
pressure and tightness testing of pressure equipment.
Site assembly guidance should specify the gasket to be
used for the test.
(a) The test gasket should be suitable for the test and
the service conditions.
(b) If a substitute or temporary gasket is selected that
does not meet the service conditions, then
(1 ) Specify a gasket that is suitable for the test conditions.
(2) Upon completion ofthe test and before the bolted
flange joint is put into service, verify that the temporary
gasket has been replaced with a gasket that is suitable for
the service conditions.
14 JOINT DISASSEMBLY
(a) Before disassembling any joint, determine whether
a controlled disassembly procedure should be specified. A
controlled disassembly procedure may be specified for
bolted flange connections meeting any of the following:
(1 ) those meeting all the criteria of (-a) through (-c)
(-a) flanges larger than DN 600 (NPS 24)
(-b) flange thicknesses greater than 125 mm (5 in.)
(-c) bolt diameters M45 (1 3 ∕4 in.) and larger
(2) where galling has occurred, or disassembly has
been problematic
(3) where high local strains could be detrimental
(e.g., glass-lined equipment, lens ring joints)
(4) where the gasket is to be retained for inspection
or failure analysis
See N o nmandatory Ap p endix J, section J-7 fo r an
example of a controlled disassembly procedure.
(b) The joint disassembly procedure should include the
following instructions, regardless of whether a controlled
disassembly procedure is used:
(1 ) Leave a sufficient number of loosened nuts in
p l ace unti l al l te ns i o n h as b e e n re l i eve d fro m the
bolted flange connection to prevent significant movement
of the flanges and guard against unanticipated movement
such as pipe spring and falling components.
(2) Select the first bolts to be loosened at locations to
direct any pressure release or residual contents away
from the assembler.
WARNING: Use of substitute or temporary gaskets during
testing instead of those designed as the final seal has occasionally resulted in gasket blowout during testing, and/or
in-service leaks due to the failure to replace the substitute or
temporary gasket with the appropriate final seal gasket.
Gas ke t b lo wo ut may in clude a p o rti o n o f the gas ke t
becoming a projectile.
13 RECORDS
(a) The owner should record in either the contract or
the assembly procedure the authorization of any representatives. See section 2 for additional information on
representatives.
(b) The user should decide the details required in the
joint assembly records, based on the relative probability
and consequences of j oint leakage (see Nonmandatory
Appendix R, para. R-2 .2 ) . Joint assembly records may
include the following information:
(1 ) joint location or identification
(2) joint class and size
(3 ) s p e c i fi c a ti o n s a n d c o n d i ti o n s o f fl a n ge s ,
fasteners, washers (including nut or washer bearing
surfaces), and gaskets
(4) date of the activity (assembly, disassembly, pressure test, etc.)
(5) names of assemblers and workers
(6) name of the inspector or person responsible for
the quality assurance or quality control of the joint
NOTE: Generally, for joints in the vertical plane, this is at the top,
followed by the bottom to drain the liquid.
6
ASME PCC-1–2022
15 REFERENCES
15.3 ASME Standards
Paragraphs 15.1 through 15.15 list publications referenced in this Standard. Unless otherwise specified, the
latest edition shall apply.
ASME B1.1, Unified Inch Screw Threads (UN, UNR, and UNJ
Thread Forms)
ASME B1.13M, Metric Screw Threads: M Profile
ASME B16.5, Pipe Flanges and Flanged Fittings: NPS 1 ∕2
Through NPS 24 Metric/Inch Standard
ASME B16.20, Metallic Gaskets for Pipe Flanges
ASME B1 6.47, Large Diameter Steel Flanges: NPS 2 6
Through NPS 60 Metric/Inch Standard
ASME B31.3, Process Piping
ASME B46.1, Surface Texture (Surface Roughness, Waviness, and Lay)
ASME PCC-2, Repair of Pressure Equipment and Piping
Publisher: The American Society of Mechanical Engineers
(ASME), Two Park Avenue, New York, NY 10016-5990
(www.asme.org)
15.1 API Publications
API Standard 660, Shell-and-Tube Heat Exchangers
API Recommended Practice 686, Recommended Practice
for Machinery Installation and Installation Design
Publisher: American Petroleum I nstitute (API ) , 2 0 0
Massachusetts Avenue NW, Suite 1100, Washington,
DC 20001–5571 (www.api.org)
15.2 ASME Boiler and Pressure Vessel Code (BPVC)
ASME BPVC, Section II, Materials: Part A — Ferrous Material Specifications
S A- 1 0 5 /S A- 1 0 5 M , S p eci fi catio n fo r C arb o n S te el
Forgings, for Piping Applications
SA-182/SA-182M, Specification for Forged or Rolled
Alloy and Stainless Steel Pipe Flanges, Forged Fittings,
and Valves and Parts for High-Temperature Service
SA-1 93 /SA-1 93 M, Specification for Alloy-Steel and
Stainless Steel Bolting for High-Temperature or High
Pressure Service and Other Special Purpose Applications
SA-194/SA-194M, Specification for Carbon and Alloy
Steel Nuts for Bolts for High Pressure or High Temperature Service, or Both
SA-453/SA-453M, Specification for High-Temperature
Bolting, With Expansion Coefficients Comparable to
Austenitic Stainless Steels
SA-540/SA-540M, Specification for Alloy-Steel Bolting
Materials for Special Applications
15.4 ASTM Publications
ASTM A2 40/A2 40M, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate,
Sheet, and Strip for Pressure Vessels and for General
Applications
ASTM A693 /A693 M, Standard for Precipitation-Hardening Stainless and Heat-Resisting Steel Plate, Sheet,
and Strip
ASTM A82 9/A82 9M, Standard Specification for Alloy
Structural Steel Plates
ASTM F436/F436M, Standard Specification for Hardened
Steel Washers Inch and Metric Dimensions
ASTM F606/F606M, Standard Test Methods for Determining the Mechanical Properties of Externally and
I nte rnal l y T h re ad e d F as te n e rs , Was h e rs , D i re ct
Tension Indicators, and Rivets
Publisher: American Society for Testing and Materials
(ASTM International) , 1 00 Barr Harbor Drive, P.O.
B o x C 7 0 0 , We s t C o ns h o h o cke n , P A 1 9 4 2 8 - 2 9 5 9
(www.astm.org)
ASME BPVC, Section II, Materials: Part B — Nonferrous
Material Specifications
SB-637, Specification for Precipitation-Hardening and
C o l d Wo r ke d N i c ke l Al l o y B a r s , F o r gi n gs , a n d
Forging Stock for M oderate or H igh-Temp erature
Service
15.5 European Committee for Standardization
Publication
NOTE: ASME SA and SB material specifications are used in ASME
PCC-1. ASTM material specifications may also be used or taken to
apply, as allowed by the applicable code of construction, for the
joint being considered.
EN 1591-1, Flanges and their joints — Design rules for
gasketed circular flange connections — Part 1: Calculation
Publisher: European Committee for Standardization
(CEN) , Avenue Marnix 17, B-1000 Brussels, Belgium
(www.cen.eu)
ASME BPVC, Section VIII, Rules for Construction of Pressure Vessels: Division 1
Publisher: The American Society of Mechanical Engineers
(ASME), Two Park Avenue, New York, NY 10016-5990
(www.asme.org)
15.6 ISO Publications
ISO 6789–2, Assembly tools for screws and nuts — Hand
torque tools — Part 2: Requirements for calibration and
determination of measurement uncertainty
7
ASME PCC-1–2022
Publisher: Occupational Safety and Health Administration
(OSHA) , U.S. Department of Labor, 200 Constitution
Avenue, Washington, DC 20210 (www.osha.gov)
ISO 7005-1, Pipe flanges — Part 1: Steel flanges for industrial and general service piping systems
ISO 2 75 0 9 , Petroleum and natural gas industries —
Compact flanged connections with IX seal ring
Publisher: International Organization for Standardization
(ISO), Central Secretariat, Chemin de Blandonnet 8, Case
P o s tal e 4 0 1 , 1 2 1 4 Ve rni e r, Ge ne va, S wi tz e rl and
(www.iso.org)
15.13 VDI Publication
VDI 2230, Systematic calculation of high duty bolted joints
— Joints with one cylindrical bolt
Publisher: Verein Deutscher Ingenieure (VDI), P.O. Box 10
11 39, 40002 Dusseldorf, Germany (www.vdi.de)
15.7 Japanese Standards Association Publication
JSA JIS B 2251, Bolt Tightening Procedure for Pressure
Boundary Flanged Joint Assembly
Publisher: Japanese Standards Association (JSA), Mita MT
Building, 3-13-12 Mita, Minato-ku, Tokyo 108-0073,
Japan (www.jsa.or.jp)
15.14 WRC Publications
WRC Bulletin 449, Guidelines for the Design and Installation of Pump Piping Systems
WRC Bulletin 538, Determination of Pressure Boundary
Joint Assembly Bolt Loads
Publisher: Welding Research Council (WRC) , P.O. Box
201547, Shaker Heights, OH 44120
15.8 MSS Publication
MSS SP-9, Spot Facing for Bronze, Iron and Steel Flanges
Publisher: Manufacturers Standardization Society of the
Valve and Fittings Industry, Inc. (MSS), 127 Park Street,
NE, Vienna, VA 22180 (www.msshq.org)
15.15 Other Publications
[1] Bickford, J. H., An Introduction to the Design and Behavior ofBolted Joints, CRC Press, United Kingdom (1995)
[2] Bickford, J. H., and Nassar, S., eds., Handbook of Bolts
and Bolted Joints, Marcel Dekker, Inc., New York (1998)
[3] Brown, W., “Hydraulic Tensioner Assembly: Load Loss
Factors and Target Stress Limits,” ASME 2014 Pressure
Ves s els and Pi p i ng C o nference, P VP2 0 1 4- 2 8 6 8 5 ,
An a h e i m , C A, J u l y 2 0 – 2 4 , 2 0 1 4 , D O I : 1 0 . 1 1 1 5 /
PVP2014-28685
[4] Brown, W., and Long, S., “Acceptable Levels of Corrosion for Pressure Boundary Bolted Joints,” ASME 2017
Pressure Vessels and Piping Conference, PVP2 01 76 5 5 0 7 , W a i ko l o a , H I , J u l y 1 6 – 2 0 , 2 0 1 7 , D O I :
10.1115/PVP2017-65507
[5] Kikuchi, T., Omiya, Y., and Sawa, T., “Effects of Nut Thinning Due to Corrosion on the Strength Characteristics
and the Sealing Performance of Bolted Flange Joints
U n d e r I n te rn a l P re s s u re ,” AS M E 2 0 1 1 P re s s u re
Vessels and Piping Conference, Volume 2: Computer
T e ch n o l o gy an d B o l te d J o i n ts , P VP 2 0 1 1 - 5 7 4 4 5 ,
pp. 3 5 –41 , B altimore, M D , July 1 7–2 1 , 2 0 1 1 , D O I :
10.1115/PVP2011-57445
[6] Kikuchi, T., and Sawa, T., “Effects ofNut Thinning on the
Bolt Load Reduction in Bolted Flange Joints Under
I nte rnal P re s s ure and B e ndi ng M o me nts ,” AS M E
2 0 1 3 P re s s u re Ve s s e l s a n d P i p i n g C o n fe re n c e ,
PVP2 0 1 3 - 9 7 1 9 1 , Paris, France, July 1 4–1 8 , 2 0 1 3 ,
DOI: 10.1115/PVP2013-97191
15.9 PIP Publication
PIP VESV1002, Design and Fabrication Specification for
Vessels: ASME Code Section VIII, Divisions 1 and 2
Publisher: Process Industry Practices (PIP), Construction
Industry Institute, The University of Texas at Austin,
3 92 5 West Braker Lane (R4500) , Austin, TX 7875 9
(www.pip.org)
15.10 SAE Publication
SAE J419, Methods of Measuring Decarburization
Publisher: SAE International, 400 Commonwealth Drive,
Warrendale, PA 15096 (www.sae.org)
15.11 TEMA Publication
Standards of the Tubular Exchanger Manufacturers Association
Publisher: Tubular Exchanger Manufacturers Association,
Inc. (TEMA), 25 North Broadway, Tarrytown, NY 10591
(www.tema.org)
15.12 U.S. Department of Labor, Occupational
Safety and Health Administration
Publication
29 CFR 1910.119, Process Safety Management of Highly
Hazardous Chemicals
8
ASME PCC-1–2022
[8] Payne, J. R., and Schneider, R. S., “On the Operating
Tightness of B16.5 Flanged Joints,”ASME 2008 Pressure
Vessels and Piping Conference, Vol. 2: Computer Applications/Technology and Bolted Joints, PVP2008-61561,
pp. 1 1 5 –1 2 4, Chicago, I L, DOI: 1 0 .1 1 1 5 /PVP2 0 0 861561
[7] Koves, W. J., “Design for Leakage in Flange Joints Under
External Loads,” ASME 2 0 0 5 Pressure Vessels and
Pip ing C onference, Vo l. 2 : C o mp uter Technolo gy,
PVP2005-71254, pp. 53–58, Denver, CO, July 17–21,
2005, DOI: 10.1115/PVP2005-71254
9
ASME PCC-1–2022
MANDATORY APPENDIX I
DEFINITIONS
ð 22 Þ
50% stud removal: see half-bolting .
bolting subject matter expert (bolting SME): an individual
considered knowledgeable in the field of bolted j oint
assembly. See Nonmandatory Appendix A, para. A-1.3.6.
applied tensioner load: the load applied to the bolt by the
tensioner (i.e., prior to load loss).
bolting supervisor: an individual trained to skill level 3 in
the topics listed in Nonmandatory Appendix A, section A2, and any supplemental topics required for bolted flange
joint assemblies conducted under the individual’s leadership. See skill level 3.
assembler: see bolting assembler.
assembly bolt stress: the target final bolt stress selected for
a joint assembly to obtain a desired target gasket stress
(see Nonmandatory Appendix O).
assistant bolting assembler: an individual who can perform
the pretightening activities as applicable to their job function, including but not limited to identifying and differentiating among the major components of a bolted flange
j oint (i.e., gasket types, flange types, lubricants, and
stud and nut material markings) , and preparing a joint
to be tightened. See Nonmandatory Appendix A, para.
A-1.3.1.
bolting trainer: an individual trained to skill level 3 in the
topics listed in Nonmandatory Appendix A, section A-2,
and any supplemental topics required for bolted flange
joint assemblies conducted by the user. See skill level 3.
centerline high/low: the alignment of piping or vessel
flanges so that the seating surfaces, the inside diameter
of the bore, or the outside diameter of the flanges matches
or meets with the greatest amount of contact surface (see
Nonmandatory Appendix E, Figure E-2-1).
backup wrench: the tool used to secure the nut or bolt head
opposite to the one being turned or torqued.
certification: written testimony of qualification.
b o lt loa d lo ss fa cto r (BL L F) : when us i ng hydrauli c
tensioners and less than 100% tensioner coverage (i.e.,
o ther than havi ng a tens i o ne r fitted to each b o lt) ,
when the second set of bolts is tensioned, the residual
tensioner load on the first set of bolts is reduced. This
loss of bolt load (expressed as a fraction of the originally
applied tensioner load) is termed the BLLF. The BLLF
occurs when more than one tensioning pass is applied;
it can be eliminated by performing 1 0 0 % tensioner
coverage. Also called flange load loss factor (FLLF) .
check pass: the tightening of all bolts in circular order at
100% of target torque until there is no further nut rotation.
circular pass: see check pass.
com m on grades: materials common to the facility or
industry in satisfactory quantity and price as to be considered the normal materials to use. For example, common
grades ofthreaded fasteners in the petroleum refining and
chemical processing industries are SA-193 B7 bolts and
SA-194 2H nuts or SA-193 B16 bolts and SA-194 4 or 7
nuts.
bolt with integral head: a threaded fastener with a fixed or
forged head on one end and employing a nut or a drilled
and tapped hole on the other end.
controlled reuse: the first and subsequent uses thereafter
that have been conducted and documented under specific
thread engagement, locations, torque, tension, lubrication,
inspection, nut replacement, handling, cleaning, and
installation guidelines.
bolt with out in tegral h ead: a fully threaded fastener
e m p l o yi ng two n uts o r o n e nu t an d a d ri l l e d and
tapped hole.
bolting assembler: an individual who assembles and disassembles bolted flange joints. See Nonmandatory Appendix
A, para. A-1.3.2.
critical issue: any issue that directly contributes to or
results from the proper or improper assembly of a joint.
critical joints: those joints in service applications designated by the owner as being of a probability or consequence to j ustify more rigorous requirements such as
assembly details, quality control checks, and/or record
keeping. Considerations in designating joints as critical
include governing design conditions (pressure, temperature, etc.) , mechanical criteria (bolt diameter, flange
NOTE: In the context of this Standard, assembler and bolting
assembler are used interchangeably.
bolting inspector: an individual who performs pretightening, in-process, and post-assembly inspection for quality
assurance. See Nonmandatory Appendix A, para. A-1.3.3.
10
ASME PCC-1–2022
grooved-metal and fiber-sheet gaskets, it is defined by the
gasket I.D. and O.D. (unless the raised-face O.D. is smaller
than the gasket O.D.) . When determining the seating
surface for gaskets that may not sit central during installation or that are designed to move on the flange face during
installation, a larger seating surface may be necessary to
account for the possibility of seating surface offset. For
example, see Nonmandatory Appendix D for the definition
of the seating surface for a ring-type joint gasket.
(b) the area on a flange where the gasket seats both
initially and finally after assembly.
diameter, gasket type, etc.), joint leakage history, and fluid
service category. Examples of critical service include
service requirements as defined by local jurisdictional requirements [e.g., in the United States, CFR 1 91 0.1 1 9
(OSHA PSM rule) ] ; lethal substance service as defined
in ASME BPVC, Section VIII, Division 1; or Category M
Fluid Service as defined in ASME B31.3.
eight-bolting: the removal ofevery bolt except eight evenly
spaced opposing bolts in preparation for breaking the
joint (typically for blinding or valve removal) during a
shutdown. The unit is offline to do this, as in the requirements for half-bolting outlined in ASME PCC-2. However,
as the joint is not broken, the line may still contain process
fluid, and there is a small likelihood of leakage with this
p ro cedure. E ight- b o lting is p erfo rmed to s p eed up
blinding or valve removal during a shutdown. A risk
assessment of the eight-bolting operation should be
carri e d o ut to e s tab l i s h that the o p e rati o n can b e
performed safely. See also four-bolting .
half-bolting: the removal of every other bolt (so the flange
is left with half the number of bolts) during plant depressurization, usually when the system is close to atmosp heric p ress ure. H alf-b olting generally co nsis ts of
removing every second bolt, relubricating them, reinstalling them, and retightening to a specified torque. The
remaining bolts are then removed, relubricated, reinstalled, and retightened to a specified torque such that
all bolts have been reinstalled. There is a small likelihood
of leakage with this procedure, particularly if the system is
accidentally repressurized. A risk assessment of the halfbolting operation should be carried out to establish that
the operation can be performed safely. Refer to ASME
PCC-2 for further information on joint-tightening activities once the unit is fully operational. Also called 50%
stud removal.
excessive gap: a condition in which two flanges are separated by a distance greater than twice the thickness of the
gasket when the flanges are at rest and the flanges will not
c o m e t o g e t h e r u s i n g r e a s o n a b l e fo r c e ( s e e
Nonmandatory Appendix E, Figure E-2 -2 ) . Also called
excessive spacing .
experience: work activities accomplished in a specific
bolted joint assembly method under the direction of qualified supervision, including the performance of the bolted
j oint assembly method and related activities but not
including time spent in organized training programs.
hard gaskets: gaskets such as grooved-metal gaskets,
corrugated metal gaskets, and flat solid-metal gaskets.
Hard gaskets are typically defined as gaskets that have
less than 1.0 mm (0.04 in.) compression during assembly.
Generally speaking, it is not appropriate to classify gaskets
as hard or soft based solely on the physical hardness or
softness of the gasket material itself. For example, 1.5-mm
(1 ∕16 -in.) thick polytetrafluoroethylene, flexible-graphite,
or fiber gaskets are classified as hard gaskets. See also
hard-faced gaskets.
flange load loss factor (FLLF): see bolt load loss factor
(BLLF) .
four-bolting: the removal of every bolt except four evenly
spaced opposing bolts in preparation for breaking the
joint (typically for blinding or valve removal) during a
shutdown. The unit is offline to do this, as in the requirements for half-bolting outlined in ASME PCC-2. However,
as the joint is not broken, the line may still contain process
fluid, and there is a small likelihood of leakage with this
procedure. Four-bolting is performed to speed up blinding
or valve removal during a shutdown. A risk assessment of
the four-bolting operation should be carried out to establish that the operation can be performed safely. See also
eight-bolting .
NOTE: Ring-type joint gaskets and lens gaskets are a special case
and are addressed separately in Nonmandatory Appendix D,
section D-4; and Nonmandatory Appendix F, section F-8.
hard-faced gaskets: gaskets constructed entirely from
metal that do no t have a soft filler material o n the
faces that contact the flange seating surfaces or that
have insufficient filler material to fill imperfections on
the flange faces. It may not be acceptable to categorize
by gasket type as extremely thin gaskets or gaskets
without sufficient filler will not fill imperfections and
therefore are categorized as hard-faced gaskets. Metalfaced gaskets, such as flat metal, ring-type j oints, or
double-j acketed gaskets, are categorized as hard-faced
gaskets. See also hard gaskets.
gasket contact surface: see gasket seating surface.
gasket sealing surface: see gasket seating surface.
gasket seating surface:
(a) the contact area of the gasket that performs the
sealing function during operation (nominally the part
of the gasket that is seated against the flange to affect
a seal). The gasket seating surface is measured in the undeformed state. For spiral-wound gaskets, this is defined as
the region between the inner diameter (I.D.) of the outer
ring and the outer diameter (O.D.) of the inner ring; for
heat exchanger joints: gasketed bolted joints that comprise
the pressure-boundary closure between the tubesheet
and the mating shell and tubeside girth flanges and
11
ASME PCC-1–2022
owner: the person, partnership, organization, or business
responsible for the leak tightness of bolted flange joint
assemblies on their pressure equipment.
th at re qui re s p e ci al as s e mb l y co ns i de rati o ns (s e e
Nonmandatory Appendix A, para. A-2 .4) . The gaskets
for these j oints are generally located entirely within
the circle enclosed by the bolt holes, with no contact
outside this circle; however, this is not intended to
exclude other configurations, such as flat-faced flanges,
from Nonmandatory Appendix A.
parallelism:
a measure of alignment, representing the
uniformity of distance between the sealing surfaces of
two fl an ge face s (s e e N o nm and ato ry Ap p e nd i x E ,
Figure E-2-3).
hot torque: see start-up retorque.
live tightening: tightening all bolts on a joint while the unit
pass: the incremental tightening steps taken to achieve the
target bolt stress.
is operational or has been in operation for a period oftime.
The technique used for tightening may be manual torque,
hydraulic torque, or hydraulic tension. However, torque
can typically no longer be considered accurate after more
than a few days of operation. Therefore, other techniques,
such as turn-of-nut or tensioning, are preferred. Singles tud re p l ace me nt i s al s o an o p ti o n, b ut the re i s a
higher associated likelihood of leak with that activity
due to the reduction in gasket stress if the tightening
is performed while the joint is pressurized. Live tightening
should not be considered the same as start-up retorque,
which is performed as part of the assembly operation; live
ti gh te n i n g i s a n o p e ra ti o n a l a cti vi ty th a t m a y b e
performed periodically to recover relaxation (typically
o n h i gh - te mp e rature j o i nts th at h ave a h i s to ry o f
leakage) or as a reaction to joint leakage. A risk assessment
of the live-tightening operation should be carried out to
establish that the operation can be performed safely. Refer
to ASME PCC-2 for further information on joint tightening
activities once the unit is fully operational.
pattern: the combination of passes applied in a sequence
leading to the assembly bolt stress.
piping joints: similar to
pressure vessel joints; however,
considerations relating to alignment and external loadings
on the j oints are mo re likely to go vern des ign and
assembly requirements. The gaskets for piping j oints
are generally located entirely within the circle enclosed
by the bolt holes, with no contact outside this circle;
however, this is not intended to exclude other configurations, such as flat-faced flanges, from Nonmandatory
Appendix A.
powered equipment: hydraulic, pneumatic, or batterypowered joint assembly equipment, such as a hydraulic
torque wrench, p neumatic torque wrench, b atterypowered torque wrench, or hydraulic bolt tensioning
equipment.
pre-pass torque: the torque that is applied to the existing
studs to confirm tightness prior to performing single-stud
replacement.
local gasket stress: for purposes of single-stud replacement, the average gasket stress along a radial line at a
given circumferential location.
lubricant:
products.
pressure vessel joints: gasketed bolted joints that comprise
the pressure-boundary closure between two flanges. The
gaskets for pressure vessel joints are generally located
entirely within the circle enclosed by the bolt holes,
with no contact outside this circle; however, this is not
intended to exclude other configurations, such as flatfaced flanges, from Nonmandatory Appendix A.
a generic term that may include antiseize
manual tightening:
the use of an uncalibrated torquing
device such as an impact wrench.
program manual: user’s documentation of the program in
accordance with Nonmandatory Appendix A, para. A-1.3.
manual torque wrench tightening:
the use of a manual
torque wrench (typically a “clicker” type) to achieve
the desired torque.
qualification: the demonstration of knowledge, skills, and
abilities, along with documented training and experience
required for personnel to properly perform the duties of a
specific job or task. Alternative solutions to those outlined
in Nonmandatory Appendix A may be used as long as they
meet the intent of this Standard and are properly justified
and documented.
nut load loss factor (NLLF):
wh e n us i ng h ydraul i c
tensioners, the load is transferred from the tensioner
to the nut as the tensioner pressure is released. As
part of this process, the thread and nut deflect, which
releases some of the load originally established by the
tensioner. This loss of load (expressed as a fraction of
the originally applied tensioner load) is termed the
NLLF. The NLLF occurs at all times when using hydraulic
tensioners (i.e., it cannot be reduced without redesign of
the joint). Also called tool load loss factor (TLLF) .
remaining gasket stress factor (RGSF):
for purposes of
single- s tud rep lacement, the ratio o f the minimum
local gasket stress when a single stud is removed to
the gasket stress when all studs are installed.
odd-bolting: see half-bolting .
online tightening: see live tightening .
representative:
a person, partnership, organization, or
business designated by the owner to carry out selected
responsibilities on the owner’s behalf.
12
ASME PCC-1–2022
does not include tightening the fastener again to turn the
nut to a tighter position from a static position.
skill level 3: a depth of knowledge that allows an individual
to justify resolutions for situations that do not meet the
scope of what would be considered normal. An individual
at thi s s kill level can exp lai n why tas ks s ho uld b e
performed a certain way.
reuse: to use more than once.
ring-type joints (RTJ): flanges fitted with metal ring-type
an individual’s exp ertise in an original way or as a
response to an original situation.
residual tensionerload: the load remaining on the bolt after
the release of the tensioner pressure (i.e., after load loss).
retighten: to tighten again in a subsequent assembly. This
skill level 4: a depth ofknowledge that allows application of
joint gaskets (as detailed in ASME B16.20).
soft gaskets: gaskets in which the movement between the
ringer pass: see check pass.
risk assessmen t: an e n gi n e e ri n g
flange faces during assembly is relatively large, e.g., polyte tr a fl u o r o e th y l e n e ( P T F E ) , s p i r a l - w o u n d , a n d
compressed-fiber or flexible-graphite-sheet gaskets.
Soft gaskets are typically defined as gaskets that have
m o re th an 1 . 0 m m (0 . 0 4 i n . ) co m p re s s i o n d u ri n g
assembly. It is not appropriate to classify gaskets as
hard or soft based solely on the physical hardness or softness of the gasket material itself. For example, 1.5-mm
( 1 ∕1 6 -in.) thick PTFE, flexible graphite, or fiber gaskets
do not have sufficient compression to be classified as
soft gaskets. See also soft-faced gaskets.
an d ri s k a n al ys i s
conducted when an activity or decision may require
extra consideration, outside of normal assembly and
operational practices, due to additional risks or modes
of failure that may not be inherently apparent. The
lack of use of this term in sections of this Standard
should not be taken to diminish the requirements for
normal risk assessment activities in those sections.
rotational-two hole: the alignment of piping or vessel
flanges so that the bolt holes align with each other,
allowing the fasteners to pass through perpendicular
to the flanges.
NOTE: Ring-type joint gaskets and lens gaskets are a special case
and are addressed separately in Nonmandatory Appendix D,
section D-4; and Nonmandatory Appendix F, section F-8.
safety data sheet (SDS): a data sheet for chemicals that
defines important information such as the levels of toxicity, flammability, and first-aid actions required.
soft-faced gaskets: gaskets
that are constructed from or
have a soft filler material on the faces that come into
contact with the flange s eating s urfaces. Soft- faced
gaskets have sufficient soft filler (such as grap hite,
rub b e r, o r p o l yte trafl uo ro e th yl e n e ) th at b o th th e
gasket substrate and the flange seating surface finish
will be filled and additional filler exists on the gasket
such that any small imperfections will also be filled as
the gasket is compressed between the flanges. It may
not be acceptable to categorize by gasket type as extremely thin sheet gaskets or gaskets without sufficient filler or
facing will not fill imperfections and therefore are categorized as hard-faced gaskets. See also soft gaskets.
sequence: the numbering protocol used to indicate the
order in which bolts are tightened.
sequential circular pass: associated with
single-stud replacement, the action of starting with one stud and
proceeding to the adjacent stud in a clockwise or counterclockwise direction.
single-stud replacement:
an operation used to replace
corroded or defective bolts, to proactively increase the
gas ket s tress to p revent leakage (typ ically in hightemperature or cyclic services) , or to reseal a small
stable leak. Also called hot bolting .
special joint: any process-specific flanged connection
requiring different or additional instruction or considerations for assembly (such as clamped connectors, valve
bonnets, and valve body joints).
NOTE: Single-stud replacement while the unit is online to
increase gasket stress or seal a small stable leak is not recommended or required if turn-of-nut tightening can be used. A risk
assessment of the single-stud replacement operation should be
carried out to establish that the operation can be performed
safely. See ASME PCC-2 for further information on joint-tightening activities once the unit is fully operational.
start-up retorque: while the unit is coming up to operating
temperature, the procedure of tightening all bolts on a
j oint in a circular pass until the nuts no longer turn.
S tart- u p re to rq u e (fo rm e rl y cal l e d h o t to rq u e ) i s
performed to increase the residual operational stress
on the gasket (to recover initial gasket relaxation) to minimize the likelihood of leakage. It is typically performed
while the unit is online but may be performed prior to
operation using heating pads to bring the flange up to
temperature. Since start-up retorque will increase the
load on only the gasket, the likelihood of leakage is significantly lower than for other activities (such as hot bolting).
skill: the ability to perform mental and physical activities
acquired or developed through training or experience.
skill level 1: a depth of knowledge characterized by recalling and reproducing the desired learning objectives.
skill level 2: a depth of knowledge that includes recall of
facts and providing the basic application of the desired
learning obj ectives. An individual at this skill level can
proficiently perform steps defined in a procedure.
stud loading: the act of increasing the tensile stress state
within the stud.
13
ASME PCC-1–2022
(b) a stud-loading method of increasing or decreasing
the load on a stud by controlling the rotation of the nut on
helical threads. Turn-of-nut involves tightening the joint
by turning one nut on each bolt by a specific amount. Turnof-nut does not require knowledge of the nut factor and
therefore can be applied at any stage during the life of the
joint. Turn-of-nut is used either to proactively increase the
gasket stress to prevent leakage (in high-temperature or
cyclic services) or to reseal a small stable leak. If turn-ofnut is performed while the unit is online, there is a small
likelihood of additional leakage. However, since the load
on the gasket will only increase, the likelihood ofleakage is
significantly less than for other activities such as hot
bolting. Bolted joints with fiber-sheet-type gaskets tend
to degrade in service and are more likely to blow out
if retightened while operating; thus, turn-of-nut for
joints with such gasket types should be limited to lowpressure nonhazardous services.
stud-loading method: the method of operator control used
to increase or decrease the stress state within a stud.
stud unloading:
the act of decreasing the tensile stress
state within the stud.
tensioner coverage:
the percentage of the number of
tensioners compared to the number of bolts on the
j oint. For example, 1 00% tensioner coverage requires
a tensioner to be fitted to every bolt (i.e., all bolts tensioned
simultaneously) , 50% tensioner coverage requires one
tensioner to be fitted to every second bolt, and 2 5 %
coverage requires one tensioner to be fitted to every
fourth bolt.
tensioning:
a s tud- lo ading metho d o f increas ing o r
decreasing the load on a stud by controlling a direct
axial force on the stud.
tighten: to apply load to the threaded fastener system
through some means ofturning ofthe nut or direct tension.
use: the process whereby a threaded fastener or group of
tool load loss factor (TLLF): see nut load loss factor (NLLF) .
torquin g: a s tu d - l o ad i n g m e th o d o f i n c re a s i n g o r
such fasteners is installed in a joint and tightened for the
purpose of obtaining and maintaining a seal between the
flanges.
decreasing the load on a stud by controlling a torqueforce acting on helical threads.
user: any entity that applies
the provisions of this Standard. Because of the broad variation of possible contract
scenarios for which this Standard might be applied, the
user could be the owner, owner’s representative, manufacturer, fabricator, erector, or other contract personnel.
training: an organized program developed to impart the
knowledge and skills necessary for qualification.
training organization: a user or organization that under-
takes the training, demonstration of knowledge, and practical examination outlined in Nonmandatory Appendix A.
working surfaces: those interfaces in the fastener system
that slide against each other when a bolted flange joint is
being tightened.
turn-of-nut:
(a) a stud-loading method of increasing or decreasing
the load on a stud by controlling the rotation of the nut on
helical threads.
14
ASME PCC-1–2022
NONMANDATORY APPENDIX A
TRAINING AND QUALIFICATION OF BOLTED JOINT ASSEMBLY
PERSONNEL
A-1 INTRODUCTION
A-1.3 Framework
A-1.1 Scope
Paragraphs A-1.3.1 through A-1.3.6 offer a framework
for skill levels and responsibilities for individuals involved
in the assembly and disassembly of bolted joints.
This Appendix outlines requirements for training and
qualification of bolted joint assemblers using procedures
in accordance with the Standard. The Appendix uses titles
for different assembler skill levels. Assigning titles to skill
levels standardizes expectations of competency for users,
contractors, labor suppliers, unions, and assembly personnel. These titles also represent specific training objectives.
Owners may refer to and require these skill levels when
contracting personnel from third parties.
The employer of the assembly personnel shall document the requirements of their training and qualification
program, which should include demonstration of knowledge and skills, along with documented training and
experience required for personnel to properly perform
the duties of a specific job or task. Alternative solutions
to those outlined in this Appendix may be used as long as
they meet the intent of this Standard and are properly
justified and documented.
The training and qualification program should
(a) evaluate the individual as semb ler’s technical
knowledge based on the types of flanges the assembler
is going to assemble
(b) assess assemblers by having them demonstrate
their skills
(c) document the content of the training and the results
of the evaluation
(d) provide a certificate stating that the trainee has
demonstrated the knowledge and skills corresponding
to the applicable skill level
When cho o s i ng p ro vi s i o ns o f thi s Ap p endi x, the
employer should specify the skill level required of an individual to meet the user’s needs.
Skill levels should be evaluated periodically as defined
by the employer.
A-1.3.1 Assistant Bolting Assembler. An assistant
bolting assembler is an individual who is able to identify
and differentiate between the maj or components of a
bolted flange joint, i.e., gasket types, flange types, lubricants, and stud and nut material markings. These individuals should be trained to skill level 1 (see Mandatory
Appendix I and Table A-1 .4-1 ) , which is appropriate
for anyone in any discipline to gain awareness of the
assembly of bolted flange joints. Skill level 1 is required
for any individual who will be assisting bolting assemblers
and for development into a future bolting assembler role.
A-1.3.2 Bolting Assembler. A bolting assembler is an
individual who assembles and disassembles bolted flange
joints. Bolting assemblers should be able to
(a) perform disassembly and assembly procedures
(b) assess pre-assembly condition
(c) inspect assembled joints
(d) complete documentation
(e) notify supervisors when tightening equipment,
flange conditions, or fasteners and gaskets are unsatisfactory
Bolting assemblers shall be trained to skill level 2 (see
Mandatory Appendix I and Table A-1.4-1) in the topics
listed in para. A-2.1 and any supplemental topics required
for their job function.
A-1.3.3 Bolting Inspector. A bolting inspector is an individual who performs pretightening, in-process, and
p o s t- a s s e m b l y i n s p e c ti o n s fo r q u a l i ty a s s u ra n c e .
Bolting inspectors will have achieved skill level 2 (see
M and ato ry Ap p e nd i x I and T ab l e A- 1 . 4 - 1 ) fo r th e
topics listed in para. A-2.1 and all supplemental endorsements that apply to the user’s scope of work. Additionally,
bolting inspectors should be knowledgeable of
(a) subject matter relevant to the inspection function
(b) ASME PCC-1
(c) the user’s bolting procedures, requirements, and
quality assurance and quality control processes
A-1.2 Definitions
See Mandatory Appendix I.
15
ð 22 Þ
ASME PCC-1–2022
Table A-1.4-1
Training Matrix
Piping
Endorsement
(Para. A-2.2)
Powered
Equipment
Endorsement
(Para. A-2.3)
Heat
Exchanger
Endorsement
(Para. A-2.4)
Skill
Level
Training of
Fundamentals
(Para. A-2.1)
1
C-1
...
...
...
2
C-2
C-2
A
A
3
C-3
C-3
A
A
4
C-4
C-4
C-2
A
Training Method
Special Joint
Endorsement
(Para. A-2.5)
Assessment Method
Training
Practical
Technical
Knowledge Demonstration Knowledge
Practical
Skills
...
CBT or ILT
NA
CBT or ILT
NA
A
CBT or ILT
ILT
CBT or ILT
ILT
A
CBT or ILT
ILT
CBT or ILT
ILT
A
ILT
ILT
ILT
ILT
Legend:
A = when applicable; refers to information the trainee is required to learn only ifit is part ofthe trainee’s job function. Otherwise, the information is
optional.
C = core information needed to perform the role; as the skill level increases, it is expected that the topics listed in Table A-2.1-1 are taught in greater
depth.
C-1 = an understanding of how to perform the role and what is needed to perform the role.
C-2 = an understanding of why bolted joint assembly activities needed to perform the role are important.
C-3 = an understanding of how to troubleshoot general bolted joint assembly issues for the roles under their supervision.
C-4 = maintaining and directing the general bolted joint assembly procedures and training materials.
CBT = computer-based training; this method is used for teaching academic and practical concepts and for testing academic knowledge.
ILT = instructor-led training; this method may be used for the entire training process but shall be used for practical demonstration and assessment of
practical skills.
NA = not applicable.
O = optional information, i.e., information the trainee is not required to learn to attain the skill level.
A-1.3.4 Bolting Supervisor. A bolting supervisor is an
i n d i v i d u a l w h o i s tr a i n e d to s ki l l l e v e l 3 ( s e e
Mandatory Appendix I and Table A-1.4-1) in the topics
listed in para. A-2.1 and any supplemental topics required
for bolted flange joint assemblies conducted under their
leadership. Bolting supervisors provide clarification to
bolting assemblers as needed.
Ad d i ti o nal , s up p l e me ntal e nd o rs e m e n ts may b e
obtained on the basic endorsements to extend the individual’s duties and responsibilities to include
(a) piping-specific (hand torque) joints
(b) powered equipment (hydraulic torque/hydraulic
tension)
(c) heat exchanger pressure-boundary bolted joints
(d) special pressure-boundary bolted joints
A-1.3.5 Bolting Trainer. A bolting trainer is an individual who is trained to skill level 3 (see Mandatory Appendix
I and Table A-1.4-1) in the topics listed in para. A-2.1 and
any supplemental topics required for bolted flange joint
assemblies conducted by the user. Bolting trainers should
also receive additional instructor-led training (ILT) on
how to deliver effective training sessions in accordance
with para. A-2.1.
A-1.5 Exempt Assembly Activities
This Appendix does not cover personnel engaged in the
assembly of structural-type bolted j oints or pressureboundary body joints on rotating equipment.
A-2 ACADEMIC TRAINING PROGRAM
A-1.3.6 Bolting Subject Matter Expert (Bolting SME).
A-2.1 Training of Fundamentals — Training
A bolting SME is an individual who is trained to skill level 4
(see Mandatory Appendix I and Table A-1 .4-1 ) in the
topics listed in section A-2 and all supplemental endorsements that apply to the user’s scope ofwork. A bolting SME
is responsible for reviewing, maintaining, and approving
procedures and training materials.
Training for all skill levels shall include the fundamentals of the assembly, operation, and quality assurance of
bolted joints. Practical and academic examinations shall
be given to establish to the satisfaction of the employer
that the trainee meets the expectations of this Appendix.
As a minimum, the employer shall address the following
topics when evaluating trainees for skill level 1 (see also
Table A-2.1-1):
(a) general health and safety precautions. While some
areas of health and safety are outside the scope of ASME
PCC-1, the following topics are included for the purpose of
awareness and for completeness in describing typical
competencies:
A-1.4 Training Program Objectives
This Appendix includes items pertaining to individuals
who participate in the assembly of bolted flange j oint
assemblies and individuals trained to skill levels 1
through 4.
Table A-1.4-1 specifies the different levels of training
and the expectations for the training and examination
process.
16
ASME PCC-1–2022
A-2.3 Powered-Equipment Endorsement —
Training
(1 ) awareness of common health issues and safety
precautions per the requirements of applicable government health and safety regulatory bodies and plant-specific regulations
(2) awareness in areas such as hazardous chemicals
and gases, personal protective equipment (PPE), hazard
communication, procedures for opening process equipment or p ip ing, hearing p rotectio n, confined-s p ace
entry, scaffold safety, personal fall protection, stairways
and ladders, rigging, respiratory protection, asbestos
considerations, and walking and working surfaces
(3) job safety analysis
(b) principles of bolt elongation, bolt load, and gasket
stress
(c) functionality of gasket and seal
(d) gasket types and their limitations
(e) bolt types and their limitations
(f) identification of correct joint components
(g) manual torque joint tightening
(h) importance of using the specified lubricant (see
section 8)
(i) techniques used for load control
(j) calibration and maintenance of bolt-tightening
equipment
(k) inspection and reporting of defects or faults
(l) procedure for preparing a joint for closure
(m) gasket handling, preparation, and installation
(n) sources of information on joint assembly
(o) safe joint disassembly and assembly
(p) joint assembly procedures
(q) correct use of additional joint components
(r) importance of joint quality-assurance procedures,
certification, and records
(s) joint disassembly
For all powered-equipment training, the curriculum
shall ensure trainees have a thorough understanding of
j oint disassembly, assembly, and tightening using the
equipment that is suited for their j ob requirements.
See Table A-2.3-1.
A-2.4 Heat Exchanger Endorsement — Training
The heat exchanger endorsement curriculum shall
ensure trainees have a thorough understanding of how
to disassemble, assemble, and tighten exchanger joints.
See Table A-2.4-1.
A-2.5 Special Joint Endorsement — Training
Special joint endorsement training should cover joints
or components that have a proprietary design, including,
but not limited to
(a) expansion joints
(b) isolated joints
(c) compact flanges
(d) hub or clamp connectors
(e) rupture disks or spectacle disks
The training curriculum shall ensure trainees have a
thorough understanding of all significant aspects of
j oint disassembly, assembly, and tightening for special
joints.
A comprehensive list of the requirements is outside the
scope of this Standard. However, the general approach
used in the previous sections for piping and exchangers
should be followed in formulating the expectations for
special j oints. As a minimum, the training curriculum
should cover the items listed in para. A-3.7.
A-2.2 Piping Endorsement — Training
The piping endorsement curriculum for skill levels 2, 3,
and 4 is detailed in Table A-2.2-1.
The practical examination requires the trainee to satisfactorily assemble by means of hand-torque tightening a
number of flange joint types, including
(a) raised-face or full-face flange
(b) ring-type joint (RTJ)
17
ASME PCC-1–2022
Table A-2.1-1
Training of Fundamentals Curriculum
Topics
(a) General health and safety precautions
Concepts Addressed
(1) Common procedures for the work permit and ensuring system isolation
(2) Finger pinch points with assembly and alignment equipment
(3) Injury from tightening tools
(4) Cleaning (material and process-medium compatibility) and a light dusting of gasket
adhesive for vertical flanges [see para. 7(b)(6)]
(5) Basic joint alignment equipment (pry-bar, drift pins; see Nonmandatory Appendix E)
(6) Site or corporate guidelines
(b) Principles of bolt elongation, bolt load, and (1) Relationship between bolt stress and bolt elongation (see section 11)
(2) Relationship between bolt stress and gasket stress during assembly and operation
gasket stress
(pressure and temperature effects)
(3) Influence of bolt length on bolt-load loss due to gasket creep relaxation and surface
embedment loss
(4) Relationship between applied torque and achieved bolt stress or load
(5) Bolting terminology, including common terms found in the field and their relationship
to each other (e.g., kips, psig, psi, lb, ft-lb, N·m, ksi, tpi)
(c) Functionality of gasket and seal
(1) Purpose of a gasket
(2) Effect of gasket stress on leak rate
(3) Effect of bolt-load loss (creep or relaxation and operating conditions) on joint leakage
and overall joint reliability
(d) Gasket types and their limitations
(1)
(2)
(3)
(4)
(5)
(6)
Summary of common gasket types and materials
Sensitivity of different gasket types to assembly procedures
Maximum allowable gasket stress
Minimum required gasket stress
Awareness of the need for chemical compatibility
Awareness of temperature limits
(e) Bolt types and their limitations
(1)
(2)
(3)
(4)
(5)
(6)
Brief detail of common bolting specifications, including yield strength
Nut–bolt combinations, nut strength versus bolt strength
Generic material temperature limits
Materials for stress-corrosion-cracking environments
Corrosion resistance
Coatings for assembly and disassembly
(f) Identification of correct joint components (1) Bolt and nut identification marks
(2) Installation of bolts and studs such that marked ends are all on the same side of the joint,
with nut identification marks facing out, to facilitate inspection
(3) Flange identification marks
(4) Gasket identification marks and spiral-wound gasket color codes and types
(5) Use of piping-arrangement drawing or system diagram to identify and verify correct
materials for gasket and fasteners
(g) Manual torque joint tightening
(1) Working parts of a manual torque wrench
(2) Setting required torque values on common types of wrenches
(3) Bolting procedures (number of cross-pattern passes) required to achieve desired bolt
torque (see section 10)
(4) Accuracy of bolt torque tightening versus that of manual tightening
(5) Variables affecting the accuracy and consistency of torque
(h) Importance of proper application and use (1) Purpose of lubricant
of specified lubricant (see section 8)
(2) Effect of type of lubricant
(3) Where to use lubricant (under nut and on bolt threads)
(4) Limitations of lubricants, including oxygen ignition, oxidation, temperature, shelf life,
catalyst poisoning, and stress corrosion cracking (compatibility with process fluid and
materials of construction)
(5) Proper application and amount of lubricant to use
(6) Contamination of lubricants during assembly
(7) Interpreting the label and material Safety Data Sheet (SDS) information
(i) Techniques used for load control
(1) Techniques used for load control by torque measurement
(2) Techniques used for load control by hydraulic tension
(3) Techniques used for load control by length or strain measurement [see paras. 10(a) and
10(b)]
(4) Accuracy of each method and relationship to service or joint criticality (see Table F-4-1)
18
ASME PCC-1–2022
Table A-2.1-1
Training of Fundamentals Curriculum (Cont’ d)
Topics
(j) Calibration and maintenance of bolttightening equipment
Concepts Addressed
(1) Requirements for maintenance of common field equipment
(2) Inspection of common field equipment (especially torque wrenches)
(3) Familiarization with methods for performing calibration and verification of common
field equipment
(4) Importance and frequency of calibration and tool verification
(k) Inspection and reporting defects or faults (1) Flange-face gasket contact surface inspection (see section 4 and Nonmandatory
Appendix D)
(2) Acceptable levels of surface flatness and imperfections corresponding to different
gasket types
(3) Bolt inspection (thread form, corrosion, and free running nut for triggering
replacement; see section 4 and Nonmandatory Appendix N)
(4) Inspection of flange and nut contact surfaces (for galling, paint, or corrosion; see
section 4)
(5) Joint gap measurement (see section 12)
(6) Joint tolerances and alignment (see Nonmandatory Appendix E)
(7) Joint-tightness leak check (see section 14)
(l) Procedure for preparing a joint for closure (1) General workflow for inspecting and preparing a joint for closure
(2) Methods for holding the gasket in place (including the detrimental effects of excessive
adhesive and use of unapproved methods such as heavy grease, lubricant, or tape; see
section 7)
(3) System cleanliness requirements
(m) Gasket handling, preparation, inspection, (1) Use of a single new (not used or damaged) gasket for final installation (see section 7)
and installation
(2) Final inspection of gasket seal surface and gasket (dimensions, type, and damage)
(3) Ensuring gasket can be inserted into joint without damage
(4) Ensuring gasket is correctly located (use of flange bolts or a light dusting of approved
adhesive sprays)
(n) Sources of information on joint assembly (1) ASME PCC-1
(2) Corporate and site standards and specifications for gaskets, bolting, and piping
(3) Corporate and site standards for joint assembly
(4) Corporate and site standards and specifications for bolt loads and assembly techniques
(o) Safe joint disassembly and assembly
(1) Ensuring pressure isolation, valve-tagging systems, and safe work practices (see
section 14)
(2) Verification of pressure isolation, gas detection, and safe entry into the system
(3) Temporary support and/or rigging considerations for joint components
(4) Working on internal joints and high-level or below-grade joints (scaffold and confinedspace entry)
(p) Joint assembly procedures
(1) Identification of correct assembly target bolt load
(2) Reason for needing a pattern (sequence and passes) in procedure
(3) Reason for needing multiple passes in the procedure (see Nonmandatory Appendix F)
(4) Measurement of joint gaps during assembly [see para. 10(a)]
(5) Hydraulic or pneumatic testing of joint after assembly (see section 14)
(6) Measurement of joint gaps after assembly [see para. 10(a)]
(7) Use ofproprietary backup wrenches and alignment tools, which may improve safety and
speed of assembly
(q) Ensuring correct use of additional joint
components
(1) Use of through-hardened washers (see Nonmandatory Appendix M).
(2) Use of conical disk (Belleville) spring washers.
(3) Use of spacers or bolt collars for the purpose of additional effective length and
elongation.
(4) Use of prevailing torque nuts, instrumented studs, reaction washers, tensioning nuts,
direct tension-indicating washers, and other special-purpose accessories.
(5) Use of proprietary nuts, washers, etc. There are innovative proprietary nuts, washers,
and other mechanical and hydraulic devices that assist the assembly process. Detailed
training on the application of these devices is available from the supplier and/or
manufacturer.
(6) Use and misuse of locking devices and locking compounds.
(r) Importance of joint quality assurance,
procedures, certification, and records
(1)
(2)
(3)
(4)
Joint assembly procedures and typical forms
Joint assembly records (see section 13)
Certification systems for tracking equipment calibration
The importance of a joint traveler sheet or assembly tag
19
ASME PCC-1–2022
Table A-2.1-1
Training of Fundamentals Curriculum (Cont’ d)
Topics
(s) Joint disassembly
Concepts Addressed
(1) Reasons for requiring a disassembly procedure (see section 14)
(2) Disassembly procedures and critical issues
(3) Use of nut splitters
Table A-2.2-1
Piping Endorsement Curriculum
Topics
Concepts Addressed
(a) Assembly technique and gasket
recognition in relation to flange-face type
(1) Flat face versus raised face versus RTJ and their appropriate gaskets
(2) Understanding of ASME B16.5 and ASME B16.47 nominal pipe size and pressure class
(3) Common flange types, including slip-on, weld neck, socket weld, threaded, and lap joint/
stub end
(4) Installation and operational characteristics (rotation, stiffness, flange sealing area, etc.)
of common flange types
(5) The importance ofmultipoint tightening or additional passes for RTJ and lens ring joints
(6) The potential consequences of mating flat-faced flanges to raised-face flanges
(7) Failure potential of brittle cast flanges on valves, pumps, and similar equipment
(b) Tightening piping joints connecting to
rotating equipment
(1) The need to ensure equipment alignment (shaft alignment) is not affected by external
loads caused by the assembly of piping connected to the rotating equipment
(2) Equipment-allowable nozzle loads and moments
(3) Purpose of piping expansion joints
(c) Tightening piping joints on pressure relief (1) Potential for inspection work-hold point to ensure that there is no blockage in the relief
devices
path
(2) Correct installation, gaskets, handling, and orientation of rupture disks and discharge
lines
(3) Confirmation of piping status by a certified inspector (if required)
(d) Tightening piping joints on and around
(1) Methods of safely restraining bellows and cold-set spring hangers
piping expansion joints and cold-set spring (2) Ensuring restraints are removed prior to operation
hangers
(3) How to recognize and report if too much force is required to bring the flanges together
(see Nonmandatory Appendix E)
(e) Importance of alignment and gap
uniformity
(1) Nonmandatory Appendix E flange alignment tolerances
(2) Tighter limits are required for shorter or stiff spans
(3) Importance ofthe bolts passing freely through the bolt holes so that the nuts rest parallel
to the flange
(f) Selecting the target bolt-assembly load
(1) Parameters that determine appropriate bolt load (flange size, gasket type, flange class,
flange type, flange material, bolt material, piping service)
(2) Determination of correct load from gasket specifications and bolt size or flange class
charts for torque and hydraulic tensioning (see section 13)
(3) Discussion of the advantages and disadvantages of the tightening methods
(g) Selecting appropriate bolt-tightening
tooling
(1) Acceptable methods in relation to bolt size
(2) Naturally occurring clearance problems related to general styles of tooling such as
hand-torque wrenches, torque multipliers, and impact wrenches
(3) Where to look for guidance (user specifications, company guidelines, tool manufacturer
websites)
20
ASME PCC-1–2022
Table A-2.3-1
Powered-Equipment Endorsement Curriculum
Topics
Concepts Addressed
(a) General health and safety precautions
(1) Safety and securing of high-pressure fluids, fittings, and hoses during operation
(2) Placement and removal of backup wrench under high loads
(3) Pinch points relative to hydraulic, electric or battery, or pneumatic torque equipment
and backup wrenches
(4) Dangers associated with socket failure under load from using the incorrect or a lowquality socket
(b) Selecting appropriate bolt-tightening
tooling
(1) Acceptable methods in relation to bolt size
(2) Naturally occurring clearance problems related to general styles of tooling such as
hydraulic inline ratchets, hydraulic square-drive ratchets, fixed-size tensioners, variablesize tensioners, hydraulic nuts, and mechanical jack nuts
(3) Bolt-load limitation of hydraulic tensioners as related to pressure, ram size, bolt size,
and bolt length
(4) Use of comparative angle of nut rotation method when standard hydraulic tooling will
not work (insufficient space for hydraulic equipment for one or two bolts)
(c) Powered equipment torque
(1) Working parts of hydraulic, electric or battery, and pneumatic torque equipment
(2) Working parts of a hydraulic pump and hydraulic or pneumatic regulator
(3) Troubleshooting hydraulic wrench, hose, hose connections, and pump failures
(4) Method of setting target torque
(5) Method of using a hydraulic torque wrench
(6) Single-point tightening versus simultaneous multiple-point tightening, and the
tightening procedure’s influence on the assembly procedure
(d) Powered equipment tension
(1) Working parts of a hydraulic bolt tensioner
(2) Working parts of a hydraulic pump and hydraulic regulator
(3) Method of setting correct bolt load (formulas for calculating the target bolt load) for the
number of tools in relation to the number of bolts in the joint
(4) Method of using a hydraulic bolt tensioner
(5) Troubleshooting of tensioner, hose, hose connections, and pump failures
(6) Use of a single tensioner versus simultaneous use of multiple tensioners and the
influence of each on the assembly procedure (see Nonmandatory Appendix O)
(7) Effect of load losses (BLLF and NLLF) and elastic recovery (indicated tensioner in
relation to final bolt load, need for overtension, and the effect of bolt grip-length to bolt
diameter ratio; see section 9 and Nonmandatory Appendix Q, para. Q-4.1)
(e) Calibration and maintenance of powered (1) Requirements for maintenance of common hydraulic field equipment
equipment
(2) Inspection of hydraulic hoses and cylinders
(3) Familiarization with methods for calibrating common hydraulic field equipment
(4) Importance and frequency of calibration
Table A-2.4-1
Heat Exchanger Endorsement Curriculum
Topics
Concepts Addressed
(a) Types of exchangers [Tubular Exchanger (1) Joint configurations, terminology, and locations
Manufacturers Association (TEMA)
(2) Gasket configurations for the different types of joints
designations] and their joints
(3) Confined gaskets versus unconfined gaskets
(4) Measurement of final joint gaps as a measure of success
(b) Bundle pushing and considerations for
assembly
(1) Bundle and channel orientation to align piping and one or more pass-partition grooves
(2) Risks during pushing (damage to the flange face or shell gasket)
(c) Tubesheet joint considerations, shell-side (1) Second gasket compression (more assembly passes may be required)
gasket damage, and recompression of shell- (2) Risks ifthe shell-side gasket seal is broken when the channel is removed (ifthe bundle is
side gaskets on tube-sheet joints
not being pulled)
(3) Inspection of pass-partition surfaces (pass-partition flush with flange facing)
(4) Consideration of tightening shoulder-type bolts from both sides
(5) Gasket pass-partition alignment
21
ASME PCC-1–2022
A-3 EXAMINATION PROGRAM
(a) Tighten a bolt using manual torque control with an
instrumented bolt to measure the achieved bolt load.
(b) Assemble a bolt without lubricant to a torque value.
(c) Assemble the same bolt as in (b) with lubricant to
the same torque value.
(d) Compare the different achieved bolt loads.
A-3.1 Academic Examination
Trainees at and above skill level 2 shall demonstrate
their academic understanding and knowledge of health,
safety, quality, and technical procedures relevant to
th e a s s e m b l y o f b o l te d j o i n ts b y c o m p l e ti o n o f a
written or online assessment. A separate set of examination questions will be required for each supplemental endors ement and s ho uld co ver the to p ics detailed in
paras. A-2.1 through A-2.5.
A-3.4 Piping Endorsement — Examination
The practical examination for a piping endorsement
requires the trainee to use a manual torque wrench to
satisfactorily assemble one or more of the following
types of flange joint:
(a) raised-face flange
(b) RTJ
(c) flat-faced flange
A-3.2 Practical Examination
Trainees at and above skill level 2 shall demonstrate
their understanding of practical skills in the assembly
of bolted joints by completing at least one bolted joint
practical demonstration and witnessing the others (see
paras. A-3.3.1 through A-3.3.3). The training of fundamentals demonstrations are designed to highlight significant
aspects of the training curriculum and shall be performed
in the presence of and to the satisfaction of the user and be
administered and witnessed by a bolting trainer as
defined in para. A-1.3.5.
The training of fundamentals demonstrations detailed
in paras. A-3.3.1 through A-3.3.3 highlight several critical
points of the j oint assembly. The user may modify the
demonstrations or substitute alternative demonstrations
for specific joint types or gaskets, provided the bolting
SME (see para. A-1.3.6) determines the desired learning
points are still achieved.
A-3.5 Powered-Equipment Endorsement —
Examination
A-3.5.1 Torque. The p racti cal examinatio n fo r a
powered-equipment torque endorsement requires the
tra i n e e to u s e h yd ra u l i c , p n e u m a ti c , o r e l e c tri c powered torque equipment to satisfactorily assemble
flange joint types, including
(a) raised-face flange
(b) RTJ
A-3.5.2 Tension. The p ractical examination for a
powered-equipment tension endorsement requires the
trainee to use hydraulic bolt tensioning to satisfactorily
assemble flange joint types, including
(a) raised-face flange
(b) RTJ
A-3.3 Examples for Training of Fundamentals —
Examination
A-3.6 Heat Exchanger Endorsement —
Examination
A-3.3.1 Importance of Correct Pretightening Basic
Skills. Perform the following on a flange test rig:
The practical examination for a heat exchanger endorsement requires the trainee to satisfactorily assemble
either a simulated heat exchanger or a heat exchanger in
the field under supervision. The exchanger joint configurations shall include
(a) tubesheet to shell
(b) bonnet or cover to tubesheet
(c) collar bolt
(a) Select the correct gasket, bolt and nut material, and
lubricant.
(b) Install gasket, bolt and nut, and lubricant correctly.
A-3.3.2 Reaction of Different Types of Gaskets to
Standard Tightening Procedure. Perform the following
on a flange test rig having four or more bolts:
(a) Assemble a four-bolt flange with a polytetrafluoroethylene (PTFE) sheet gasket, small-diameter flange with
a spiral-wound gasket without inner and outer rings using
a tightening pattern and ensure the gasket is centrally
l o cate d o n th e rai s e d face . M o n i to r th e b o l t l o ad ,
stress, or elongation during the tightening to see when
it stabilizes (number of passes).
(b) Repeat (a) with a spiral-wound gasket with inner
and outer rings.
(c) Repeat (a) with a corrugated or grooved-metal
gasket that has graphite facing.
A-3.7 Special Joint Endorsement — Examination
The practical examination for a special joint endorsement should cover j oints or components that have a
proprietary design, including, but not limited to, expansion joints, isolated joints, compact flanges, hub or clamp
connectors, and rupture disks or spectacle disks.
The practical examination requires the trainee to satisfactorily assemble the specific special joint.
Key learning objectives should include
(a) seal surface preparation
(b) the importance of alignment and gap uniformity
A-3.3.3 Demonstration of the Effect of Lubricants.
Perform the following:
22
ASME PCC-1–2022
A-4 QUALITY ASSURANCE
(c) gasket handling, preparation, and installation
(d) specific assembly steps, tooling, or procedures
pertaining to the joint consideration
A-4.1 Program Manual
The employer should have a program manual that
outlines how the program is administered and includes
a reference to the trai ni ng co urs e s yllab us , les s o n
p l an s , a n d e xa m i n a ti o n d o c u m e n ts . T h e p ro gra m
manual should form the basis for demonstration of
compliance with this Appendix and with the training organization.
A-3.8 Skill-Level Evaluation
As recommended in para. A-1.1, skill-level evaluation
should occur on a regular basis. Users who prefer to implement a periodic evaluation process should use both the
academic and the practical parts of the examination
process relevant to the individual’s role, skill level, and
any supplemental endorsements.
Individuals with legacy Appendix A training or qualification certificates should use the academic and practical
examinations detailed within this Appendix to complete
or update their certification.
A-4.2 Program Records
The employer should maintain records of all training
and assessments conducted in compliance with this
Ap p endi x fo r traceab i lity p urp o s es . Thes e reco rds
should include copies of certification and examinations
and a feedback process for review and monitoring of
program effectiveness.
23
ASME PCC-1–2022
ð 22 Þ
NONMANDATORY APPENDIX B
DESCRIPTION OF COMMON TERMS
The definitions formerly in this Appendix have been
moved to Mandatory Appendix I.
24
ASME PCC-1–2022
NONMANDATORY APPENDIX C
RECOMMENDED GASKET SEATING SURFACE FINISH FOR
VARIOUS GASKET TYPES
See Table C-1.
Table C-1
Recommended Gasket Seating Surface Finish for Various Gasket Types
Gasket Seating Surface Finish,
μm (μin.) [Note (1)]
Gasket Description
Spiral-wound
3.2–6.4 (125–250)
Soft-faced metal core with facing layers such as flexible graphite, PTFE, or other conformable materials
3.2–6.4 (125–250)
Flexible graphite reinforced with a metal interlayer insert
3.2–6.4 (125–250)
Grooved metal
1.6 max. (63 max.)
Flat solid metal
1.6 max. (63 max.)
Flat metal jacketed
2.5 max. (100 max.)
Soft cut sheet, thickness ≤1.5 mm (≤ 1 ∕16 in.)
3.2–6.4 (125–250)
Soft cut sheet, thickness >1.5 mm (> 1 ∕16 in.)
3.2–13 (125–500)
NOTE: (1) Finishes listed are average surface roughness values and apply to either the serrated concentric or serrated spiral finish on the gasket
seating surface of the flange.
25
ð 22 Þ
ASME PCC-1–2022
ð 22 Þ
NONMANDATORY APPENDIX D
GUIDELINES FOR ALLOWABLE GASKET SEATING SURFACE
FLATNESS AND DEFECT DEPTH
D-1 INTRODUCTION
In this case, it is conservative to calculate the overall gaps
between the flanges atpoints around the circumference and
use the single-flange tolerances as shown in Table D-2-1M/
Table D-2-1 to determine the acceptability of the gap.
The imperfections and flange flatness limits listed in this
Appendix are intended as inspection guidance. Ifthe limits
are exceeded, then engineering judgment should be used
to determine whether the particular defect is acceptable.
Such determinations should consider factors such as the
actual gasket construction, flange flexibility, bolt spacing,
joint leakage history, and the risk associated with leakage.
D-3 FLANGE FACE IMPERFECTION TOLERANCES
The tolerances shown in Table D-3-1M/Table D-3-1 are
separated into two categories, depending on whether a
hard or a soft gasket is being used in the j oint (see
M an d a to ry Ap p e n d i x I ) . C a re s h o u l d b e ta ke n to
ensure the correct tolerances are emp loyed for the
gasket being installed. It is important to note that the tolerances apply to the gasket seating surface.
D-2 FLANGE FACE FLATNESS TOLERANCES
A flatness check of the flange gasket seating surface is
usually considered for large-diameter flanges, those with a
history of leakage, or when it is desired to establish that
the surface meets a particular flatness criterion.
The tolerances in Table D-2-1M/Table D-2-1 are dependent on the type of gasket employed and are categorized
based on the expected axial deflection of the gasket at a
typical target assembly stress.
Soft gaskets (see Mandatory Appendix I) are more
tolerant of flange flatness imperfections but are typically
more difficult to assemble. Hard gaskets (see Mandatory
Appendix I) have less compression than soft gaskets and,
while this can help with improved assembly due to less
bolt interaction (cross-talk), it generally means that hard
gaskets are more sensitive to flange flatness out-of-tolerance. It is suggested that load-compression test results for
the gasket being used be obtained from the gasket manufacturer to determine which ofthe listed flatness tolerance
limits should be employed. Some types of gaskets, such as
expanded or microcellular PTFE, elastomers, and flexible
graphite, with sufficient initial thickness and applied load,
may provide suitable sealing performance to justify the
use of larger tolerances (ref. [1] ).
The highest and lowest measurements around the entire
ci rcumference o f the gas ket s eating s urface may b e
recorded and the differences between the two compared
to the sum of the radial and circumferential limits stated
in Table D-2 -1 M/Table D-2 -1 . Mating flanges that have
only one possible alignment configuration may also be
gauged to determine that any waviness of the flange
faces is complimentary, such that the seating surfaces
fo llo w the s ame p atte rn. This i s fo und in multi p as s
exchanger joints and is often caused by thermal distortion.
D-4 RTJ GASKETS
Flanges for RTJ gaskets are typically inspected for flange
flatness and seating surface imperfections in a different
manner than that for raised-face flanges. The flange flatness and groove dimensions are examined prior to joint
disassembly by inspection of the gap between the outer
edges of the raised faces. If the gap at any location around
the joint circumference is less than 1.5 mm (0.062 in.),
then consideration should be given to repair or remachining of the groove at the next opportunity. This eliminates the possibility of the flange faces touching during
assembly, which can lead to joint leakage. Once the joint is
d i s a s s e m b l e d , t h e g a s k e t s e a t i n g s u r fa c e ( s e e
Figure D-4-1) should be inspected for damage in accordance with the requirements listed for hard gaskets in
Tab le D - 3 - 1 M /Tab le D - 3 - 1 . I n additio n, the gas ket
groove may be inspected for cracking using a suitable
inspection technology. Refer to ASME PCC-2 , Article
305 for repair considerations.
D-5 REFERENCE
[1] Brown, W., “Background on the New ASME PCC-1 2010
Appendices D & O ‘Guidelines for Allowable Gasket
C o ntact S urface Fl atne s s and D e fe ct D e p th ’ and
‘Assembly Bolt Load Selection,’ ” ASME 2010 Pressure
Ves s els and Pi p i ng C o nference, P VP2 0 1 0 - 2 5 7 6 6 ,
B e l l e vu e , WA, J u l y 1 8 - 2 2 , 2 0 1 0 , D O I : 1 0 . 1 1 1 5 /
PVP2010-25766
26
ASME PCC-1–2022
Table D-2-1M
Flange Seating Face Flatness Tolerances (Metric)
Measurement
Hard Gaskets
Acceptable variation in radial (across the surface) flange seating surface flatness
T1
T2
Maximum acceptable pass-partition surface height vs. flange face
−0.25 mm <
Acceptable variation in circumferential flange seating surface flatness
GENERAL NOTE: See Figures D-2-1 and D-2-2 for the description of T1 and
T2
< 0.15 mm
P<
Soft Gaskets
T1
T2
< 0.15 mm
0.0 mm
< 0.25 mm
< 0.25 mm
−0.50 mm <
P<
0.0 mm
measurement methods.
Table D-2-1
Flange Seating Face Flatness Tolerances (U.S. Customary)
Measurement
Hard Gaskets
Acceptable variation in radial (across the surface) flange seating surface flatness
T1
T2
Maximum acceptable pass-partition surface height vs. flange face
−0.010 in. <
Acceptable variation in circumferential flange seating surface flatness
GENERAL NOTE: See Figures D-2-1 and D-2-2 for the description of T1 and
T2
< 0.006 in.
P<
Soft Gaskets
T1
T2
< 0.006 in.
0.0 in.
< 0.01 in.
< 0.01 in.
−0.020 in. <
P < 0.0 in.
measurement methods.
Figure D-2-1
Flange Circumferential Variation Tolerance, T1
Al i gn th e m easu rem en t tool an d set th e d atu m at fou r poin ts
arou n d th e ci rcu m feren ce. Take m easu rem en ts arou n d th e
fu l l ci rcu m feren ce to compare to tol eran ce
T1 . I n cremen t ou t
6 m m ( 0. 25 i n . ) an d repeat measu remen t. Repeat u n ti l en ti re
gasket seati n g su rface (gray regi on ) h as been measu red.
H i gh
Low
T1
= th e ma xi mu m acceptabl e
di fferen ce between th e h i gh est an d
l owest measu remen t for each
ci rcu m feren ti al l i n e of measu rem en t.
27
ASME PCC-1–2022
Figure D-2-2
Flange Radial Variation Tolerance, T2
T2 = the maximu m acceptable
difference across each radial
line of measurement
Align the measurement tool and set
the datum at four points around the
circumference on the inner edge of the
seating surface. Take measurements
along radial lines across the gasket
seati ng surface (gray region) every
200 mm (8 in.) or less until the entire
gasket seating surface has been
measured.
< 200 mm
(8 in.)
P
P = axial height from the inner edge of
the flange seating surface to the
pass-partition plate seating surface
Table D-3-1M
Allowable Defect Depth vs. Width Across Face
(Metric)
Measurement
Table D-3-1
Allowable Defect Depth vs. Width Across Face
(U.S. Customary)
Hard-Faced Gaskets
Soft-Faced Gaskets
Hard-Faced Gaskets
Soft-Faced Gaskets
rd < w/4
<0.76 mm
<1.27 mm
rd < w/4
<0.030 in.
<0.050 in.
w/4 < rd < w/2
<0.25 mm
<0.76 mm
w/4 < rd < w/2
<0.010 in.
<0.030 in.
Measurement
w/2 < rd < 3 w/4
Not allowed
<0.13 mm
w/2 < rd < 3 w/4
Not allowed
<0.005 in.
rd > 3 w/4
Not allowed
Not allowed
rd > 3 w/4
Not allowed
Not allowed
GENERAL NOTES:
(a) See Figures D -3 -1 and D -3 -2 for the description of defect
measurement and for the definition of w.
(b) Defect depth is measured from the peak ofthe surface finish to the
bottom of the defect.
GENERAL NOTES:
(a) See Figures D -3 -1 and D -3 -2 for the description of defect
measurement and for the definition of w.
(b) Defect depth is measured from the peak ofthe surface finish to the
bottom of the defect.
28
ASME PCC-1–2022
Figure D-3-1
Flange Surface Damage Assessment: Pits and Dents
Gasket seating surface
Si
Pits and dents
ng
rd
le
Do not locally polish, grind, or buff
seating surface (remove burrs only)
rd
Jo
ine
rd
d
rd =
projected radial distance across
seating surface
d = radial measurement between
defects
w = radial width of gasket seating
surface
rd
d # rdi
rdi
Scattered; rd = the sum of rdi
Figure D-3-2
Flange Surface Damage Assessment: Scratches and Gouges
Scratches
and gouges
rd
rd
Do not locally polish, grind, or buff
seating surface (remove burrs only)
pro j ected radial distance across
seating surface
rd =
29
rd
rd
ASME PCC-1–2022
Figure D-4-1
RTJ Gasket Seating Surface Assessment
Oval
RTJ
d/2
Seating
surface ( w)
Octagonal
RTJ
w*
d
4w*/3
Seating
surface ( w)
Gasket seating width w = d/2 or 4w*/3
30
ASME PCC-1–2022
NONMANDATORY APPENDIX E
FLANGE JOINT ALIGNMENT GUIDELINES
E-1 CHECKS, MEASUREMENTS, OR
VERIFICATIONS
E-3 ALIGNMENT METHODS AND TOOLS
(a) Specify acceptable tools and methods for correcting
misaligned flanges.
(b) Flanges that cannot be aligned with accepted alignment methods and tools should be evaluated and replaced
if necessary. For misalignments on piping systems larger
than DN 450 (NPS 18), consider the special guidelines of
WRC Bulletin 449, para. 1.2.3 concerning the modification
or rebuilding of a portion of the system.
(c) Flanges such as blind flanges and tube bundles not
attached to external piping or components can be aligned
with sufficient support or force.
(d) When external alignment devices are used, flanges
should be brought into uniform contact with the uncompressed gasket face using a maximum of 10% of the total
target assembly bolt load. No single bolt should be tightened above 20% of the single target bolt load.
(e) When no external alignment devices are used,
flanges should meet the alignment tolerances for PRL
and GP (s ee Table E - 2 - 1 and Figure E - 2 - 3 ) using a
maximum of 20% of the total target assembly bolt load.
(a) Specify the necessary sequence of the alignment
procedure and any checks, measurements, or verifications
during the alignment process.
(b) See Nonmandatory Appendix J, section J-2 for the
final joint alignment assessment.
E-2 VERIFICATION METHODS AND TOLERANCES
(a) For machinery, refer to API Recommended Practice
(RP) 686, Chapter 6, Sections 4.6 through 4.9 and Figure
B-4 for acceptable alignment tolerances.
(b) WRC Bulletin 449, para. 1 .2 .2 covers stringent
alignment tolerances that apply to critically stiff (as
described in WRC Bulletin 449) piping systems, such
as rotating equipment nozzles.
(c) Centerline (CL) tolerance should be measured at
four locations, each approximately 90 deg apart on the
flange. Hold a straight edge parallel to the axis of one
flange and fl us h wi th the o uts i de di amete r (O . D . ) .
Extend the straight edge to the adj oining flange and
measure the distance from the straight edge surface to
th e s a m e s u r fa c e o n th e a d j o i n i n g fl a n g e ( s e e
Figure E-2-1).
(d) Gap (GP) tolerance is a measurement of the spacing
between the seating surfaces (see Figure E-2-2).
(e) Parallelism (PRL) tolerance is a measurement
defining the uniformity of distance between the sealing
surfaces of two flange faces. PRL tolerance is calculated
as the difference b etween the larges t and s malles t
d i s tan ce b e twe e n th e two s e al i n g s u rfa ce s at th e
sealing surface O.D. (see Figure E-2-3).
(f) Rotational two-hole (RTH) ensures the flange holes
are rotationally aligned to one another such that fasteners
can be installed perpendicular to both flanges. Measure
RTH by confirming the hole centers are aligned (see
Figure E-2-4).
(g) For common alignment tolerances, see Table E-2-1.
E-4 ENGINEERING EVALUATION
(a) When the alignment of flanges requires more force
than can be exerted by hand or common hand and hammer
alignment tools, such as spud wrenches and alignment
pins, engineering should be consulted.
(b) For alignment of flanges connected to pumps or
rotating equipment, care should be taken to prevent
the introduction of strain into the equipment housing
or bearings (see API RP 686).
(c) If excessive force is required to bring flange gaps
into compliance, a pipe stress analysis should be considered, especially if it is suspected the walls have thinned or
the piping has been modified from the original design.
31
ð 22 Þ
ASME PCC-1–2022
Figure E-2-1
Centerline High/Low
CL tolerance
GENERAL NOTE: See para. E-2(c) .
Figure E-2-2
Excessive Spacing Gap
GP tolerance
GENERAL NOTE: See para. E-2(d) .
Figure E-2-3
Parallelism
Max.
PRL = max. – min.
Min.
GENERAL NOTE: See para. E-2(e) .
32
ASME PCC-1–2022
Figure E-2-4
Rotational Two-Hole
Table E-2-1
Common Alignment Tolerances
RTH
Maximum Tolerance,
mm (in.) [Note (1)]
Property
CL
1.5 (1 ∕16 )
GP
Gasket thickness × 2
PRL
0.8 (1 ∕3 2 )
RTH
3 (1 ∕8 )
NOTE: (1) These common alignment tolerances are to be used with
section E-3 and Figures E-2-1 through E-2-4.
GENERAL NOTE: See para. E-2(f).
33
ASME PCC-1–2022
ð 22 Þ
NONMANDATORY APPENDIX F
JOINT-TIGHTENING PRACTICES AND PATTERNS
F-1 INTRODUCTION
manufacturers , the us er’ s exis ting p rocedures , and
industry-recognized bolting standards.
Turn-of-nut is generally used for adjusting previously
tightened bolts or for live tightening and is not usually
used for initial assembly (see Mandatory Appendix I) .
Torque turn does not depend on a K-factor, requires
the back nut not to turn, and is an alternative method
for otherwise inaccessible bolts.
Tightening practices depend on the target bolt stress
( s e e N o n m a n d a to ry Ap p e n d i x O ) a n d ti gh te n i n g
method, including load control and tool selection. Useraccepted patterns and practices should also include
load verification or experience.
The patterns in para. F-6.1 have received wide acceptance in the industry for their performance as proven
patterns. These patterns may be modified based on
user experience. However, new patterns should be verified as acceptable by the user. New patterns should be
develo p ed us ing meas urement o f key indicato rs o f
assembly effectiveness, such as sealing performance, resid ual b o l t l o ad , uni fo rm i ty o f gas ke t co mp re s s i o n ,
assembly effort, or complexity (ref. [1 ] ) . Hydrostatic
testing does not provide sufficient evidence to confirm
an assembly procedure’s effectiveness.
The applicability of a pattern may or may not be transferable to other facilities or applications. The user should
use sound engineering practice and judgment to determine a specific pattern’s applicability to a given application.
Us e rs s ho uld re vi ew th e fo l l o wi ng cauti o ns and
co ncerns with the us e o f any alternative as s emb ly
patterns:
(a) localized overcompression of the gasket
(b) uneven tightening resulting in flange distortion or
gasket compression
(c) nonuniform application of gasket seating load
(d) excessive load or unloading of the gasket during
assembly
(e) resulting nonparallel flanges
F-3 BOLT-LOAD VERIFICATION
The user should decide the levels of tightening controls
and verification the assembler should apply to any particular joint or group of joints to be tightened.
Load verification involves an additional step to confirm
the desired bolt load. Load-verification methods include
bolt elongation and direct load measurement.
Bolt elongation measurement (see Nonmandatory
Appendix J, section J-3) is a way to verify bolt stress; it
typically requires temperature monitoring and measurement of the bolts both before and after tightening. It also
requires specially prepared bolts, measuring equipment, a
knowledgeable operator, and a calibrated micrometer or
ultrasonic measurement equipment.
Load cells or other proprietary devices can make direct
load measurements. Load cells can provide real-time feedback but may have temperature limitations. There are
various load-sensing devices that the user may select
based on the specific situation. Most direct load measurement methods depend on operator training and calibration.
F-4 TIGHTENING PRACTICES
Not all pressure boundary bolted joints demand the
same level of systematic care and scrutiny. Table F-4-1
s h o ws e xam p l e s o f ti gh te n i n g m e th o d s an d l o ad control techniques based on the service application.
Users should consider the risks (safety, environmental,
financial) associated with potential joint failure according
to the service category of the joint under consideration.
The user should also consider the history of the joint and
the likelihood ofleakage (see Nonmandatory Appendix O).
F-2 BOLT-LOAD CONTROL
Load control is applying a determined amount of force
during the tightening process. Common load-control
methods include torque, tension, and turn-of-nut, a
prescribed amount of nut rotation. The use of impact
wrenches is an example of uncontrolled turning.
The user should determine the target assembly bolt
stress and target torque. Nonmandatory Appendix O
provides guidance on computing assembly bolt stress.
O ther acceptable sources for bolt stress calculation
include target torque or load values from equipment
34
ASME PCC-1–2022
Table F-4-1
Example Tightening Practices Based on Service Application
Service
Application
Tools
Tightening Method
Load-Control Technique
Mild
Manual or auxiliary-powered tools
Single- or multitool tightening patterns Consistent procedures per industry
best practices or torque control
Intermediate
Manual or auxiliary-powered tools or Single- or multitool tightening patterns Torque or tension control
torque- or tension-measuring tools
Critical
Torque- or tension-measuring tools
Single- or multitool tightening patterns Torque or tension control
User specifies requirements for final
bolt elongation/load verification
F-5 TOOL SELECTION FOR LOAD CONTROL
All of the patterns discussed in this Appendix involve
incremental tightening in steps expressed as percentages
of target torque. The percentage values assigned to these
intermediate passes are acceptable ranges and are not
exact or required point values. Multiple tools can be
used with all these patterns to increase assembly efficiency and tool movement. However, using more than
four tools is not in the scope of this Appendix.
(a) Users should select the tooling to ensure it meets
the safety, accuracy, repeatability, and efficiency goals.
Tool selection should consider the assembly procedures,
lubrication, joint component conditions, specific material
properties, stud load requirements, proper calibration
and maintenance of the tool, and bolting assembler
training and competency.
(b) Hand-operated torque wrenches are generally
practical for bolts 25 mm (1 in.) in diameter or less or
bolts with assembly torque less than 680 N·m (500 ft-lb).
(c) Powered torque and tensioning tools are available
to create bolt preload. (See Nonmandatory Appendix A for
guidance on training for the proper handling of powered
equipment.)
(d) Proprietary devices that create or measure applied
torque or achieved loads may also be part of the tooling
decision.
F-6.1 Torque Tightening Patterns
This Appendix presents multiple proven torque tightening patterns. The traditional Star Pattern is a gradual
and conservative pattern that applies the same torque to
every bolt on each pass. This controlled approach may
re nd e r mo re e ve n l o ad i ng o f h i gh l y co m p re s s i b l e
gaskets and reduce the potential for damage to thin,
nonstandard, or fragile flanges . The o ther p atterns
des crib ed in this Ap p endix s p eed up the as s emb ly
process by reducing the number of bolts touched at
the same torque value per pass and accelerating the percentage of target torque applied per pass. In addition to
less effort, these patterns have been found to result in
i mp ro ved gas ke t co mp res s io n fo r typ i cal indus try
gaskets and are, therefore, preferred (ref. [2 ] ) . See
Nonmandatory Appendix J, section J-5 for information
on bolt grouping for flanges with large amounts of studs.
F-6 TIGHTENING PATTERNS
Users should select a tightening pattern that uses a
sequence with passes that counters elastic interaction
effects. The term “sequence” refers to the numbering
protocol used to indicate the bolts’ tightening order.
The term “passes” refers to the incremental loading
and tightening steps leading to the assembly target
bolt stress. The term “pattern” refers to the application
of passes in a specified sequence. The patterns listed
in this Appendix demonstrate efficiency by less tool movement (torque values quickly step up).
The patterns in this Appendix
(a) provide experience-proven examples that may be
followed with confidence on most applications, avoiding
unproductive experimentation or trial-and-error
(b) demonstrate how past patterns may be accelerated
by some combination of
(1 ) eliminating the need to tighten every bolt in
every pass
(2) accelerating the target torque values between
passes
(c) have advantages and disadvantages when applied
to certain types of flange joints
F-6.1.1 Pattern # 1 — Star Pattern. Referred to as the
Legacy Pattern in previous editions of ASME PCC-1, the
Star Pattern was historically the industry’s most-used
tightening pattern. While assemblers are familiar with
this pattern, it is the most conservative of the bolting
patterns listed in ASME PCC-1 because it touches every
bolt at the same torque value on each pass.
F-6.1.1.1 Sequence. Tab le F- 6 . 1 . 1 . 1 - 1 invo lve s
marking the tightening sequence number in the correct
order on the flange so the assembler can follow tool movement.
Establish one primary method of marking the tightening sequence on a given flange. It is recommended to use
Table F-6.1.1.1-1 to mark the bolt-tightening sequence so
that a separate reference table is not required during the
35
ASME PCC-1–2022
Table F-6.1.1.1-1
Star and Modified Star Pattern Sequencing
No. of
Bolts
Bolt-Numbering Sequence to Be Marked Clockwise on the Flange
4
1, 3, 2, 4
8
1, 5, 3, 7, 2, 6, 4, 8
12
1, 9, 5, 3, 11, 7, 2, 10, 6, 4, 12, 8
16
1, 9, 5, 13, 3, 11, 7, 15, 2, 10, 6, 14, 4, 12, 8, 16
20
1, 17, 9, 5, 13, 3, 19, 11, 7, 15, 2, 18, 10, 6, 14, 4, 20, 12, 8, 16
24
1, 17, 9, 5, 13, 21, 3, 19, 11, 7, 15, 23, 2, 18, 10, 6, 14, 22, 4, 20, 12, 8, 16, 24
28
1, 25, 17, 9, 5, 13, 21, 3, 27, 19, 11, 7, 15, 23, 2, 26, 18, 10, 6, 14, 22, 4, 28, 20, 12, 8, 16, 24
32
1, 25, 17, 9, 5, 13, 21, 29, 3, 27, 19, 11, 7, 15, 23, 31, 2, 26, 18, 10, 6, 14, 22, 30, 4, 28, 20, 12, 8, 16, 24, 32
36
1, 33, 25, 17, 9, 5, 13, 21, 29, 3, 35, 27, 19, 11, 7, 15, 23, 31, 2, 34, 26, 18, 10, 6, 14, 22, 30, 4, 36, 28, 20, 12, 8, 16, 24, 32
40
1, 33, 25, 17, 9, 5, 13, 21, 29, 37, 3, 35, 27, 19, 11, 7, 15, 23, 31, 39, 2, 34, 26, 18, 10, 6, 14, 22, 30, 38, 4, 36, 28, 20, 12, 8, 16, 24, 32, 40
44
1, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 3, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 2, 42, 34, 26, 18, 10, 6, 14, 22, 30, 38, 4, 44, 36, 28, 20, 12, 8, 16,
24, 32, 40
48
1, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 3, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 2, 42, 34, 26, 18, 10, 6, 14, 22, 30, 38, 46, 4, 44, 36, 28, 20,
12, 8, 16, 24, 32, 40, 48
52
1, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 3, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 2, 50, 42, 34, 26, 18, 10, 6, 14, 22, 30, 38, 46, 4, 52,
44, 36, 28, 20, 12, 8, 16, 24, 32, 40, 48
56
1, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 3, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55, 2, 50, 42, 34, 26, 18, 10, 6, 14, 22, 30, 38,
46, 54, 4, 52, 44, 36, 28, 20, 12, 8, 16, 24, 32, 40, 48, 56
60
1, 57, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 3, 59, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55, 2, 58, 50, 42, 34, 26, 18, 10, 6, 14,
22, 30, 38, 46, 54, 4, 60, 52, 44, 36, 28, 20, 12, 8, 16, 24, 32, 40, 48, 56
64
1, 57, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 61, 3, 59, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55, 63, 2, 58, 50, 42, 34, 26, 18, 10,
6, 14, 22, 30, 38, 46, 54, 62, 4, 60, 52, 44, 36, 28, 20, 12, 8, 16, 24, 32, 40, 48, 56, 64
68
1, 65, 57, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 61, 3, 67, 59, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55, 63, 2, 66, 58, 50, 42, 34,
26, 18, 10, 6, 14, 22, 30, 38, 46, 54, 62, 4, 68, 60, 52, 44, 36, 28, 20, 12, 8, 16, 24, 32, 40, 48, 56, 64
72
1, 65, 57, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 61, 69, 3, 67, 59, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55, 63, 71, 2, 66, 58, 50,
42, 34, 26, 18, 10, 6, 14, 22, 30, 38, 46, 54, 62, 70, 4, 68, 60, 52, 44, 36, 28, 20, 12, 8, 16, 24, 32, 40, 48, 56, 64, 72
76
1, 73, 65, 57, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 61, 69, 3, 75, 67, 59, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55, 63, 71, 2, 74,
66, 58, 50, 42, 34, 26, 18, 10, 6, 14, 22, 30, 38, 46, 54, 62, 70, 4, 76, 68, 60, 52, 44, 36, 28, 20, 12, 8, 16, 24, 32, 40, 48, 56, 64, 72
80
1, 73, 65, 57, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 61, 69, 77, 3, 75, 67, 59, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55, 63, 71, 79,
2, 74, 66, 58, 50, 42, 34, 26, 18, 10, 6, 14, 22, 30, 38, 46, 54, 62, 70, 78, 4, 76, 68, 60, 52, 44, 36, 28, 20, 12, 8, 16, 24, 32, 40, 48, 56, 64, 72,
80
84
1, 81, 73, 65, 57, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 61, 69, 77, 3, 83, 75, 67, 59, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55, 63,
71, 79, 2, 82, 74, 66, 58, 50, 42, 34, 26, 18, 10, 6, 14, 22, 30, 38, 46, 54, 62, 70, 78, 4, 84, 76, 68, 60, 52, 44, 36, 28, 20, 12, 8, 16, 24, 32, 40,
48, 56, 64, 72, 80
88
1, 81, 73, 65, 57, 49, 41, 33, 25, 17, 9, 5, 13, 21, 29, 37, 45, 53, 61, 69, 77, 85, 3, 83, 75, 67, 59, 51, 43, 35, 27, 19, 11, 7, 15, 23, 31, 39, 47, 55,
63, 71, 79, 87, 2, 82, 74, 66, 58, 50, 42, 34, 26, 18, 10, 6, 14, 22, 30, 38, 46, 54, 62, 70, 78, 86, 4, 84, 76, 68, 60, 52, 44, 36, 28, 20, 12, 8, 16,
24, 32, 40, 48, 56, 64, 72, 80, 88
36
ASME PCC-1–2022
tightening process. Maintaining two numbering systems
on the same flange may confuse assemblers.
Nonmandatory Appendix J, Table J-6-1 is identical to a
table in a previous edition (ASME PCC-1–2019, Table 3).
This table refers to a Legacy Cross-Pattern numbering
system. This numbering system allows, e.g., the quick
identification of bolt number 20 in a 40-bolt flange but
requires Table 3 as a reference for the tightening sequence
during the tightening process. Numbering the bolts in a
clockwise order can also help reference leak locations.
Nonmandatory Appendix J, Figure J-5-1 is identical to a
figure in a previous edition (ASME PCC-1–2019, Figure 4).
This figure has information on grouping bolts for flanges
with a large number of bolts.
(a) Mark the tightening sequence numbers using the
s a m e p r o c e d u r e a s th e b a s i c S ta r P a tte r n fr o m
Table F-6.1.1.1-1.
(b) Following the sequence numbers as marked per (a),
tighten each bolt as described in (1) through (5) below.
(1 ) Pass #1 . 20% to 30% of target torque on bolts
numbered 1 to 4
(2) Pass #2. 50% to 70% of target torque on bolts
numbered 5 to 8
(3) Pass #3. 100% of target torque on the remaining
bolts in the sequence
(4) Pass #4. 100% of target torque on all bolts in the
s e q u e n c e m a y b e r e q u i r e d fo r s o ft ga s ke ts ( s e e
Mandatory Appendix I) ; also recommended for problematic joints
(5) Check Pass. 100% of target torque on all bolts
using a rotational or circular sequence until there is no
further nut rotation
Figure F-6.1.1.2.2-2 shows an example of how to use
multiple tools with the Modified Star Pattern.
F-6.1.1.2 Passes. There are two options for applying
the passes with the Star Pattern. Option 1 applies the traditional sequence and passes. Option 2 is the Modified Star
Pattern as it requires tightening fewer bolts per pass,
which has the advantage of resulting in more uniform
gasket compression as the residual gasket stress upon
commencement of the circular passes is substantially
higher.
F-6.1.2 Pattern # 2 — Quadrant Pattern. The Quadrant
Pattern has been successful in applications across the full
range of gaskets and joint configurations. The Quadrant
Pattern speeds assembly efficiency by
(a) reducing sequence marking time
(b) tightening only selected bolts in the initial pass
(c) rapidly increasing the torques applied in subsequent passes to the final values
NOTE: When the flange consists of soft or soft-faced gaskets (see
M andatory App endix I ) , they may be more susceptible to
damage . There fo re a gap meas urement is reco mm ended
during the assembly process. (See also section F-8 for additional
guidance on highly compressible gaskets.)
F-6.1.1.2.1 Option 1 — Star Pattern. The Star
Pattern follows a prescribed tightening sequence as set
in Table F-6.1.1.1-1, and progressive tightening passes
as outlined in (a) through (c).
(a ) M ark the ti ghteni ng s e quence numb ers (p e r
Table F-6.1 .1 .1 -1 ) on the flange, beginning with the
bolt at an arbitrary 12 o’clock position.
(b) After numbering the bolts, it is no longer necessary
for the assembler to have a copy of Table F-6.1.1.1-1 in
hand.
(c) Following the sequence numbers as marked per (a),
tighten each bolt as described in (1) through (4) below. See
also Figure F-6.1.1.2.1-1.
(1 ) Pass #1 . All bolts in sequence to 20% to 30% of
the target torque
(2) Pass #2. All bolts in sequence to 50% to 70% of
the target torque
(3) Pass #3. All bolts in sequence to 1 00% of the
target torque
(4) Check Pass. All bolts in circular order at 100% of
target torque until there is no further nut rotation
F-6.1.2.1 Sequence. There are two options for the
numbering sequence with the Quadrant Pattern (see
Figure F-6.1.2.1-1). Option 1 (cross sequence) requires
numbering the bolts as would occur in a cross sequence,
while Option 2 (circular sequence) numbers the quadrants in a circular manner (effectively swapping quadrants 2 and 3 when compared to the cross sequence) .
The quadrant circular sequence allows for optimal assembler efficiency by eliminating unnecessary tool movement
but is only suitable for joints with 15 or more bolts. It has
the advantage of eliminating the need to number the bolts,
since the next bolt to be assembled is the first loose bolt in
each quadrant.
F-6.1.2.1.1 Option 1 — Cross Sequence. Number
four primary bolts as follows: mark the bolt at the 12
o’clock position #1 , the bolt at the 3 o’clock position
#3 , the bolt at the 6 o’clock position #2 , and the bolt
at th e 9 o ’ cl o ck p o s i ti o n # 4 . F o r e ach o f th e fo u r
primary bolts, mark the adj acent bolt in the clockwise
directio n b y adding 4 to the p revio us b o lt numb er
u n ti l th e n e xt p r i m a r y b o l t i s r e a c h e d . T a b l e
F-6.1.2.1.1-1 provides a tightening sequence chart that
follows the cross sequence numbering.
F-6.1.1.2.2 Option 2 — Modified Star Pattern. The
Modified Star Pattern is an accelerated version of the Star
Pattern. The Modified Star Pattern involves touching
fewer bo lts in the early p asses and simultaneously
i n c r e a s i n g th e ta r g e t to r q u e i n e a c h p a s s . S e e
Figure F-6.1.1.2.2-1.
F- 6 . 1. 2 . 1. 2 O p ti o n 2 — Ci rcu lar Seq u en ce.
Number the four primary bolts as follows: mark the
b o l t at th e 1 2 o ’ cl o ck p o s i ti o n # 1 , th e b o l t at th e
37
ASME PCC-1–2022
Figure F-6.1.1.2.1-1
Pattern # 1 (Star Pattern): 24-Bolt Basic Example
24
16
24
8
1
17
1
23
9
2
22
12
3
21
20
19
22
18
14
13
5
6
7
17
6
8
16
9
15
10
F-6.1.3.1 Sequence. Number the bolt at the 12 o’clock
position #1, the bolt at the 3 o’clock position #3, the bolt at
the 6 o’clock position #2, and the bolt at the 9 o’clock position #4. See Figure F-6.1.3.1-1.
5
4
20
4
for gaskets susceptible to damage from uneven loading
(see sections F-8 and F-9).
This method has been successfully used in limited applications using harder gaskets in joint configurations. The
Circular Pattern is suitable for soft gaskets but might not
be suitable for highly compressible gaskets (ref. [3] ).
F-6.1.3.2 Passes. Following the sequence numbers,
tighten each bolt as described in (a) through (d) below. See
Figure F-6.1.3.2-1.
(a) Pass #1 . Tighten the four marked bolts in sequence
to 20% to 30% of target torque.
(b) Pass #2. Repeat tightening the same four marked
bolts in sequence to 50% to 70% of target torque.
(c) Pass #3. Repeat tightening the same four marked
bolts in sequence to 100% of target torque.
(d) Ch eck Pass #4. Starting at the bolt marked #1 ,
torque all bolts to 100% of target torque using a rotational
or circular sequence until there is no further nut rotation.
21
3
19
11
10
14
11
13
18
2
7
12
23
15
GENERAL NOTE: Outer numbers indicate the tightening sequence.
F-6.1.3.3 Circular Pattern With Multiple Tools.
I ntroducing multiple tools into the Circular Pattern
extends this p attern’ s us age to so fter, mo re highly
co mp ressible gaskets. See Figure F- 6. 1 . 3 . 3 -1 for an
example of two tools being used to tighten the flange.
3 o’clock position #2, the bolt at the 6 o’clock position #3,
and the bolt at the 9 o’clock position #4. For each of the
four primary bolts, mark the adjacent bolt in the clockwise
direction by adding 4 to the previous number until the
next primary bolt is reached. Table F-6.1.2.1.2-1 provides
a tightening sequence chart that follows the circular
sequence numbering.
F-6.2 Tension Tightening Patterns
See Nonmandatory Appendix Q.
F-7 DEVELOPING NEW PROCEDURES
F-6.1.2.2 Passes. Tighten each bolt as described in
(a) through (e) below. See Figure F-6.1.2.2-1.
(a) Pass #1 . 2 0% to 3 0% of target torque on bolts
numbered 1 through 4.
(b) Pass #2. 5 0% to 70% of target torque on bolts
numbered 5 through 8.
(c) Pass #3. 100% of target torque on the remaining
bolts in the sequence.
(d) Pass #4. 100% of target torque on all bolts in the
sequence may be required for soft gaskets such as spiralwound and double-jacketed gaskets or problematic joints.
(e) Check Pass. All bolts in circular order at 100% of
target torque until there is no further nut rotation.
The procedures contained in sections F-1 through F-6
are not intended to be all-encompassing or to limit the
development of application-specific alternative procedures. New alternative procedures may be developed
that may be more effective and result in better sealing
performance or less assembly effort for a given application. However, caution should be used in accepting new
assembly procedures. There are, generally, two viable
options for accepting bolted joint assembly procedures
that are not listed in these guidelines.
(a) Option 1 is to use the procedure and learn ifit works
by experience.
This is difficult to imp lement across the industry
because it requires people who closely monitor their
b o l ti n g s u cce s s ra te an d are ab l e to d i ffe re n ti ate
between bolting procedure–induced failure and other
causes of failure (incorrect flange design, incorrect bolt
load specification, incorrect gasket selection, incorrect
bolt assembly, etc.). Successful completion ofa hydrostatic
test is not considered sufficient evidence to confirm the
acceptability of an assembly procedure. Bolting contractors may not have sufficient knowledge of the long-term
F-6.1.3 Pattern # 3 — Circular Pattern. The Circular
Pattern consists of initially tightening only four bolts
to align the j oint and begin seating the gasket before
commencing circular passes. I t is much simpler and
requires less tool movement. This pattern lends itself
b e s t to a p p l i ca ti o ns u s i n g h ard gas ke ts (s e e
Mandatory Appendix I). It is generally not recommended
38
Figure F-6.1.1.2.2-1
Pattern # 1 (Star Pattern): 24-Bolt Modified Star Example
Pass 1 : 20% to 30% Target Torque
24
8
23
1
9
3
4
22
14
6
18
7
6
8
4
21
3
22
15
18
7
11
13
18
12
2
8
7
13
21
3
19
4
22
14
6
18
7
17
14
10
11
13
15
18
23
12
2
8
15
3
19
11
13
15
18
23
11
10
14
10
7
21
9
16
6
11
10
5
19
9
15
5
4
12
2
7
15
23
39
Pass 4: 1 00% Target Torque
1
24
24
23
1
22
12
9
14
6
18
7
8
15
10
4
21
3
22
19
11
10
14
11
13
18
2
7
12
3
15
23
GENERAL NOTE: Outer numbers indicate the tightening sequence.
1
2
22
5
4
3
4
21
13
20
5
19
6
18
7
17
14
9
16
23
20
19
6
24
9
2
20
5
17
1
21
13
20
23
22
12
5
4
20
22
24
8
3
21
4
17
16
2
Check Pass: 1 00% Target Torque (Circular Sequence)
1
24
17
16
8
Pass 4 (cont’d): 1 00% Target Torque
6
8
15
10
11
13
18
2
7
12
15
23
19
6
18
7
17
8
9
16
11
10
14
3
19
9
16
21
5
15
10
14
11
13
12
ASME PCC-1–2022
14
10
6
11
10
3
20
6
16
9
20
5
17
23
2
21
19
14
19
17
1
22
12
5
4
13
9
16
3
20
19
24
8
20
13
5
17
9
2
21
20
20
23
1
16
22
12
5
4
21
24
8
1
24
17
16
2
22
12
1
24
17
16
Pass 3: 1 00% Target Torque
Pass 2: 50% to 70% Target Torque
1
24
Figure F-6.1.1.2.2-2
Modified Star Pattern With Multiple Tools
4
6
4
1
5
2
6
3
5
1
6
5
6
3
2
2
3
5
6
4
Ci rcu l ar pass
at 1 00% u n ti l
n o m ovem en t
1
6
5
3
2
3
2
5
6
1
4
6
1
2
6
4
4
Beg i n at 3s.
i n order to 1 00%
4
1
6
5
3
2
3
2
5
6
1
4
ASME PCC-1–2022
5
3
4
3
1
2
1
5
5
4
1
1
4
3
40
4
2
Ti g h ten a l l g rou ps
2
6
3
5
4
1
6
3
2
5
3
Ti g h ten 2s to 50%
4
1
2
2
Ti g h ten 1 s to 50%
6
3
5
4
1
1
6
3
6
5
5
2
2
3
4
1
ASME PCC-1–2022
Figure F-6.1.2.1-1
Pattern # 2 (Quadrant Pattern): 24-Bolt Examples
20
16
23
24
1
24
1
5
20
2
22
12
3
19
22
18
17
6
7
17
8
16
14
9
15
8
14
13
12
6
2
23
11
9
2
3
4
19
3
23
18
7
19
7
17
8
15
6
10
10
14
13
12
7
3
( a ) Opti on 1 : Qu a dra n t Cross Pa ttern
2
9
11
19
21
6
15
15
17
5
16
11
13
4
20
21
10
10
5
1
21
5
20
4
18
4
23
24
1
22
12
13
21
8
16
9
24
22
11
14
18
( b) Opti on 2: Qu a dra n t Ci rcu l a r Pa ttern
GENERAL NOTE: Outer numbers indicate the tightening sequence.
engineering practice and j udgment should be used to
determine the applicability of a specific procedure or
part of a procedure to a given application.
o p erating s ucces s o f their p ro cedure to b e ab le to
comment on the ap plicability of the procedure to a
given application.
Implementing a new procedure to “see if it works”
s h o u l d b e d o n e wi th c a u ti o n a n d m a y n o t b e a n
o p tio n, as the co ns equences o f failure will us ually
outweigh any advantage gained. Another possibility to
implement this option is to use a bolting contractor’s
o r o ther facility’ s exp erience to p ro ve the metho d
works (this often means relying on secondhand information) . However, this process also requires the input of
someone knowledgeable enough to determine if the
experience in the other facilities will translate into
your facility. The user is required to determine if his particular application is within the limits of the procedure.
(b) Option 2 is to test a proposed procedure in an
experimental setting and to measure certain parameters
(such as uniformity of bolt preload; even gasket compression; and physical damage to the gaskets, flanges, and
bolts) versus defined pass–fail criteria. Limitations of
applying the experimental results to facility applications
and comparison to existing procedures (see section F-1)
should be considered.
Many facilities are successfully using alternative procedures developed over time and thereby are reducing their
workload considerably, but over a limited range of gasket
and flange types and operating conditions. Their experience and the applicability ofthe procedure may or may not
be transferable to other facilities and applications. Sound
F-8 RTJ AND LENS-TYPE GASKETS
RTJ and lens-type gaskets have additional considerations that should be accounted for when determining
the assembly sequence to use. The axial movement of
the flanges is significant for these gasket types. Also,
they are sensitive to flange misalignment either before
o r during j oint assembly. D ue to a large amount of
axial movement of the flanges during assembly, the
elastic interaction is significant. Therefore, it is necessary
to perform multiple pattern passes to ensure uniform joint
closure. These j oints typically require multiple final
circular passes to ensure the desired target load.
For large-diameter RTJ flanges (>NPS 1 2 ) , this may
mean performing four pattern passes and six or more
circular passes.
A significant advantage of fewer passes is possible if
using multiple tightening heads (two, four, or more) to
tighten bolts on the j oint simultaneously. This process
has the effect ofbringing the joint together more uniformly
and reducing mechanical interaction. Gap measurement
b etwee n the o uter diameter o f the rai s e d faces o r
flange is recommended (see Nonmandatory Appendix J,
s e c ti o n J - 2 ) . T h e re d u c ti o n i n th e ga p s h o u l d b e
41
ASME PCC-1–2022
Table F-6.1.2.1.1-1
Quadrant Pattern Cross Sequence
No. of
Bolts
Bolt-Numbering Sequence to Be Marked Clockwise on the Flange [Note (1)]
4
1, 3, 2, 4
8
1, 5, 3, 7, 2, 6, 4, 8
12
1, 5, 9, 3, 7, 11, 2, 6, 10, 4, 8, 12
16
1, 5, 9, 13, 3, 7, 11, 15, 2, 6, 10, 14, 4, 8, 12, 16
20
1, 5, 9, 13, 17, 3, 7, 11, 15, 19, 2, 6, 10, 14, 18, 4, 8, 12, 16, 20
24
1, 5, 9, 13, 17, 21, 3, 7, 11, 15, 19, 23, 2, 6, 10, 14, 18, 22, 4, 8, 12, 16, 20, 24
28
1, 5, 9, 13, 17, 21, 25, 3, 7, 11, 15, 19, 23, 27, 2, 6, 10, 14, 18, 22, 26, 4, 8, 12, 16, 20, 24, 28
32
1, 5, 9, 13, 17, 21, 25, 29, 3, 7, 11, 15, 19, 23, 27, 31, 2, 6, 10, 14, 18, 22, 26, 30, 4, 8, 12, 16, 20, 24, 28, 32
36
1, 5, 9, 13, 17, 21, 25, 29, 33, 3, 7, 11, 15, 19, 23, 27, 31, 35, 2, 6, 10, 14, 18, 22, 26, 30, 34, 4, 8, 12, 16, 20, 24, 28, 32, 36
40
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40
44
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 4, 8, 12, 16, 20, 24, 28, 32,
36, 40, 44
48
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 4, 8, 12, 16, 20,
24, 28, 32, 36, 40, 44, 48
52
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 4, 8,
12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52
56
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46,
50, 54, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56
60
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38,
42, 46, 50, 54, 58, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60
64
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 2, 6, 10, 14, 18, 22, 26, 30,
34, 38, 42, 46, 50, 54, 58, 62, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64
68
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 2, 6, 10, 14, 18, 22,
26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68
72
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 2, 6, 10, 14,
18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72
76
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 75, 2, 6,
10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76
80
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 75, 79,
2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 78, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76,
80
84
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 75,
79, 83, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 78, 82, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64,
68, 72, 76, 80, 84
88
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 85, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71,
75, 79, 83, 87, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 78, 82, 86, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52,
56, 60, 64, 68, 72, 76, 80, 84, 88
NOTE: (1) This sequence was established using the following procedure:
(a) Establish the reference locations corresponding to 12:00, 3:00, 6:00, and 9:00 on the flange face.
(b) Mark the bolts corresponding to the reference locations as follows: #1 at 12:00, #3 at 3:00, #2 at 6:00, and #4 at 9:00.
(c) Mark the next bolt that is clockwise from bolt #1 by adding 4, i.e., mark the next bolt clockwise from bolt #1 (1 + 4), or #5.
(d) Repeat (c) for each succeeding bolt until bolt #3 is reached.
(e) Start on the next bolt that is clockwise from bolt #3 and repeat (c), i.e., mark the next bolt clockwise from bolt #3 (3 + 4), or #7.
(f) Repeat (e) for each succeeding bolt until bolt #2 is reached.
(g) Start on the next bolt that is clockwise from bolt #2 and repeat (c), i.e., mark the next bolt clockwise from bolt #2 (2 + 4), or #6.
(h) Repeat (g) for each succeeding bolt until bolt #4 is reached.
(i) Start on the next bolt that is clockwise from bolt #4 and repeat (c), i.e, mark the next bolt clockwise from bolt #4 with (4 + 4), or #8.
(j) Repeat (i) until the last bolt is reached.
42
ASME PCC-1–2022
Table F-6.1.2.1.2-1
Quadrant Pattern Circular Sequence
No. of
Bolts
Bolt-Numbering Sequence to Be Marked Clockwise on the Flange [Note (1)]
4
1, 2, 3, 4
8
1, 5, 2, 6, 3, 7, 4, 8
12
1, 5, 9, 2, 6, 10, 3, 7, 11, 4, 8, 12
16
1, 5, 9, 13, 2, 6, 10, 14, 3, 7, 11, 15, 4, 8, 12, 16
20
1, 5, 9, 13, 17, 2, 6, 10, 14, 18, 3, 7, 11, 15, 19, 4, 8, 12, 16, 20
24
1, 5, 9, 13, 17, 21, 2, 6, 10, 14, 18, 22, 3, 7, 11, 15, 19, 23, 4, 8, 12, 16, 20, 24
28
1, 5, 9, 13, 17, 21, 25, 2, 6, 10, 14, 18, 22, 26, 3, 7, 11, 15, 19, 23, 27, 4, 8, 12, 16, 20, 24, 28
32
1, 5, 9, 13, 17, 21, 25, 29, 2, 6, 10, 14, 18, 22, 26, 30, 3, 7, 11, 15, 19, 23, 27, 31, 4, 8, 12, 16, 20, 24, 28, 32
36
1, 5, 9, 13, 17, 21, 25, 29, 33, 2, 6, 10, 14, 18, 22, 26, 30, 34, 3, 7, 11, 15, 19, 23, 27, 31, 35, 4, 8, 12, 16, 20, 24, 28, 32, 36
40
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40
44
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 4, 8, 12, 16, 20, 24, 28, 32,
36, 40, 44
48
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 4, 8, 12, 16, 20,
24, 28, 32, 36, 40, 44, 48
52
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 4, 8,
12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52
56
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47,
51, 55, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56
60
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39,
43, 47, 51, 55, 59, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60
64
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 3, 7, 11, 15, 19, 23, 27, 31,
35, 39, 43, 47, 51, 55, 59, 63, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64
68
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 3, 7, 11, 15, 19, 23,
27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68
72
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 3, 7, 11, 15,
19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72
76
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 3, 7,
11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 75, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76
80
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74, 78,
3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 75, 79, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72, 76,
80
84
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70, 74,
78, 82, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 75, 79, 83, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64,
68, 72, 76, 80, 84
88
1, 5, 9, 13, 17, 21, 25, 29, 33, 37, 41, 45, 49, 53, 57, 61, 65, 69, 73, 77, 81, 85, 2, 6, 10, 14, 18, 22, 26, 30, 34, 38, 42, 46, 50, 54, 58, 62, 66, 70,
74, 78, 82, 86, 3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51, 55, 59, 63, 67, 71, 75, 79, 83, 87, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52,
56, 60, 64, 68, 72, 76, 80, 84, 88
NOTE: (1) This sequence was established using the following procedure:
(a) Establish the reference locations corresponding to 12:00, 3:00, 6:00, and 9:00 on the flange face.
(b) Mark the bolts corresponding to the reference locations as follows: #1 at 12:00, #2 at 3:00, #3 at 6:00, and #4 at 9:00.
(c) Mark the next bolt that is clockwise from bolt #1 by adding 4, i.e., mark the next bolt clockwise from bolt #1 (1 + 4), or #5.
(d) Repeat (c) for each succeeding bolt until bolt #2 is reached.
(e) Start on the next bolt that is clockwise from bolt #2 and repeat (c), i.e., mark the next bolt clockwise from bolt #2 (2 + 4), or #6.
(f) Repeat (e) for each succeeding bolt until bolt #3 is reached.
(g) Start on the next bolt that is clockwise from bolt #3 and repeat (c), i.e., mark the next bolt clockwise from bolt #3 (3 + 4), or #7.
(h) Repeat (g) for each succeeding bolt until bolt #4 is reached.
(i) Start on the next bolt that is clockwise from bolt #4 and repeat (c), i.e, mark the next bolt clockwise from bolt #4 with (4 + 4), or #8.
(j) Repeat (i) until the last bolt is reached.
43
Figure F-6.1.2.2-1
Pattern # 2 (Quadrant Pattern): 24-Bolt Accelerated Cross Example
Pass 1 : 20% to 30% Target Torque
1
23
24
1
23
2
22
4
8
19
6
18
7
3
8
17
6
18
7
8
12
15
14
6
44
2
1
23
12
8
4
24
1
16
20
6
18
7
8
17
9
15
6
13
12
7
24
1
3
7
4
11
2
GENERAL NOTE: Outer numbers indicate the tightening sequence.
13
12
11
8
17
9
16
15
13
12
23
15
11
19
24
1
15
2
3
21
4
20
5
19
6
18
7
17
8
9
16
15
10
14
11
19
21
17
5
7
14
14
22
13
22 1 8
11
10
15
23
6
18
9
16
2
3
21
8
17
Check Pass: 1 00% Target Torque
19
10
14
10
18
24
23
17
6
14
20
19
16
18
13
5
10
21
5
4
21
11
22
4
21
12
3
23
20
9
3
22
13
9
2
19
Pass 4 (cont’d): 1 00% Target Torque
5
2
7
10
11
Pass 4: 1 00% Target Torque
22
9
16
1
20
19
17
24
22
12
4
23
ASME PCC-1–2022
13
3
5
10
14
16
2
20
9
16
15
1
24
20
21
5
20
4
24
5
22
3
21
Pass 3: 1 00% Target Torque
Pass 2: 50% to 70% Target Torque
10
14
13
12
11
ASME PCC-1–2022
Figure F-6.1.3.1-1
Pattern # 3 (Circular Pattern): 24-Bolt Example
permanent uneven compression of the gasket, leading to
leaks. PTFE gaskets, p articularly the virgin and the
expanded types, are examples of gaskets that are susceptible to this kind ofpermanent, uneven deformation. When
using highly compressible gaskets, it is important to use
tightening sequences that apply load as gradually as
possible.
Sequences in which faster tightening is required may
not be appropriate for highly compressible gaskets.
M u l ti p l e c h e ck p a s s e s (o fte n th re e o r m o re ) wi l l
almost certainly be needed to achieve even compression
and accurate final bolt stress. For critical or problematic
joints, monitoring the amount and uniformity of flange
gaps per Nonmandatory Appendix J, section J-2 may be
necessary.
When using a pattern that consists of multiple tools that
are not relocated, it is important to allow sufficient time
(10 min to 15 min) between passes for these gaskets to
conform to the applied loads.
1
24
1
23
2
22
3
21
4
20
4
5
19
6
18
7
3
8
17
16
9
15
10
14
11
13
F-10 REFERENCES
12
[1] Brown, W., “Efficient Assembly of Bolted Joints,” ASME
2 0 0 4 P re s s u re Ve s s e l s a n d P i p i n g C o n fe re n c e ,
PVP2 0 0 4- 2 6 3 5 , S an D iego , C A, J uly 2 5 –2 9 , 2 0 0 4,
DOI: 10.1115/PVP2004-2635
[2] Brown, W., Waterland, J., and Lay, D., 2010, “Background on the New ASME PCC-1:2010 Appendix F ‘Alternatives to Legacy Tightening Sequence/Pattern,’” ASME
2 0 1 0 P re s s u re Ve s s e l s a n d P i p i n g C o n fe re n c e ,
PVP2 0 1 0 -2 5 772 , B ellevue, WA, July 1 8 –2 2 , 2 0 1 0 ,
DOI: 10.1115/PVP2010-25772
[3] “Bolt Tightening Procedure for Pressure Boundary
Flanged Joint Assembly,” JSA JIS B 2251, 2008
2
GENERAL NOTE: Outer numbers indicate the tightening sequence.
uniform during assembly, which indicates the correct
seating of the gasket.
F-9 HIGHLY COMPRESSIBLE SOFT GASKETS
VULNERABLE TO UNEVEN COMPRESSION
Highly compressible gaskets pose additional assembly
challenges. Uneven gasket compression due to misaligned
flanges or loading too quickly during tightening can cause
45
Figure F-6.1.3.2-1
Pattern # 3 (Circular Pattern): 24-Bolt Step-by-Step Example
Pass 1 : 20% to 30% Target Torque
23
1
24
23
2
4
21
6
18
7
4
3
9
15
12
46
1
2
22
3
4
21
20
5
19
6
18
7
17
8
9
16
15
10
14
11
13
8
10
11
2
Check Pass: 1 00% Target Torque
24
7
13
2
23
18
14
12
GENERAL NOTE: Outer numbers indicate the tightening sequence.
12
4
4
3
5
19
6
18
7
17
3
8
9
16
15
10
14
11
13
2
12
ASME PCC-1–2022
13
6
9
3
20
19
15
11
2
21
5
16
10
14
4
17
8
1
22
3
20
19
17
23
2
21
5
20
16
1
24
22
3
22
4
1
1
1
24
Pass 3: 1 00% Target Torque
Pass 2: 50% to 70% Target Torque
Figure F-6.1.3.3-1
Pattern # 3 (Simultaneous Multibolt Circular Pattern): 24-Bolt Step-by-Step Example (Two Tools)
Pass 1 : 20% to 30% Target Torque (Simultaneous)
Pass 2: 50% to 70% Target Torque (Simultaneous)
1
2
1
2
Ti g h ten 4 bol ts
to 30% torq u e
al l bol ts at 1 00%
u n ti l n o m ovem en t
1
2
1
ASME PCC-1–2022
47
Check Pass 4 Onward: 1 00% Target Torque (Simultaneous)
Ti g h ten 4 bol ts
to 1 00% torq u e
2
1
ci rcu l ar pass, ch eck
2
to 70% torq u e
1
Keepi n g tool s opposi te
1
Ti g h ten 4 bol ts
2
1
Check Pass 3: 1 00% Target Torque (Simultaneous)
ASME PCC-1–2022
ð 22 Þ
NONMANDATORY APPENDIX G
SINGLE-STUD REPLACEMENT
Nonmandatory Appendix G is in the course of preparation.
48
ASME PCC-1–2022
NONMANDATORY APPENDIX H
BOLT ROOT AND TENSILE STRESS AREAS
See Tables H-1M and H-1.
Table H-1M
Bolt Root and Tensile Stress Areas (Metric Threads)
Bolt Size, Basic Thread
Designation [Note (1)]
M12 × 1.75
Root Area
2
mm [Notes (2), (3)]
ð 22 Þ
Tensile Stress Area
2
in. [Note (4)]
2
mm [Notes (2), (5)]
in. 2 [Note (4)]
72
0.1122
84
0.1307
M14 × 2
100
0.1546
115
0.1788
M16 × 2
138
0.214
157
0.243
M20 × 2.5
217
0.336
245
0.379
M22 × 2.5
272
0.422
303
0.470
M24 × 3
313
0.485
353
0.547
M27 × 3
414
0.641
459
0.712
M30 × 3.5
503
0.780
561
0.869
M33 × 3.5
629
0.975
694
1.075
M36 × 4
738
1.144
817
1.266
M39 × 4
M42 × 4.5
890
1.379
976
1.513
1 018
1.578
1 121
1.738
M45 × 4.5
1 195
1.852
1 306
2.024
M48 × 5
1 343
2.082
1 473
2.283
M52 × 5
1 615
2.504
1 758
2.725
M56 × 5.5
1 863
2.887
2 030
3.147
M64 × 6
2 467
3.824
2 676
4.148
M72 × 6
3 222
4.994
3 460
5.362
M80 × 6
4 077
6.319
4 344
6.733
M90 × 6
5 287
8.195
5 591
M100 × 6
6 652
10.31
6 995
8.666
10.84
NOTES:
(1) Metric thread designations are given in bolt size (millimeters) and pitch (millimeters) (e.g., M14 × 2 refers to a 14-mm-diameter bolt with a
2-mm-pitch thread).
(2) The root and tensile stress areas are based on coarse-thread series for sizes M64 and smaller, and 6-mm-pitch thread series for sizes M72 and
larger.
(3) The root area is computed from the cross-sectional area taken from the “Minimum Minor Diameter (Rounded Form), d3 ,” found in ASME
B1.13M, Table 14 for the respective basic thread designation, assuming a tolerance class of 6g.
(4) The equivalent root and tensile stress areas in U.S. Customary units represent a soft conversion of their respective values in SI units.
(5) The tensile stress area is computed from the formula provided in ASME B1.13M, Nonmandatory Appendix B, para. B-1.
49
ASME PCC-1–2022
Table H-1
Bolt Root and Tensile Stress Areas (Inch Series)
Root Area
Bolt Size, in.
Threads per Inch
in. 2 [Notes (1), (2)]
Tensile Stress Area
mm 2 [Note (3)]
in. 2 [Notes (1), (4)]
mm 2 [Note (3)]
1
∕2
13
0.1257
5
∕8
11
0.202
3
∕4
10
0.302
195
0.334
215
7
∕8
9
0.419
271
0.462
298
1
8
0.551
356
0.606
391
1 1 ∕8
8
0.728
470
0.790
510
1 1 ∕4
8
0.929
599
1.000
645
3
1 ∕8
8
1.155
745
1.233
795
1 1 ∕2
8
1.405
907
1.492
1 5 ∕8
8
1.68
1 084
1.78
1 148
1 3 ∕4
8
1.98
1 277
2.08
1 342
1 7 ∕8
8
2.30
1 486
2.41
1 555
2
8
2.65
1 711
2.77
1 787
2 1 ∕4
8
3.42
2 208
3.56
2 297
2 1 ∕2
8
4.29
2 769
4.44
2 865
2 3 ∕4
8
5.26
3 393
5.43
3 503
3
8
6.32
4 080
6.51
4 200
3 1 ∕4
8
7.49
4 831
7.69
4 961
3 1 ∕2
8
8.75
5 645
8.96
5 781
3 3 ∕4
8
10.11
6 522
10.34
6 671
4
8
11.57
7 462
11.81
7 619
81
0.1419
92
130
0.226
146
963
NOTES:
(1) The root and tensile stress areas are based on coarse-thread series for sizes 1 in. and smaller, and 8-pitch thread series for sizes 1 1 /8 in. and
larger.
(2) The root area is taken from ASME B1.1, Table 6 (Basic Dimensions for Coarse-Thread Series) and Table 11 (Basic Dimensions for 8-Thread
Series) under the column labeled “Section at Minor Diameter at D − 2 h b .”
(3) The equivalent root and tensile stress areas in SI units are a soft conversion of their respective values in U.S. Customary units.
(4) The tensile stress area is taken from ASME B1.1 Table 6 (Basic Dimensions for Coarse-Thread Series) and Table 11 (Basic Dimensions for 8Thread Series). See ASME B1.1, Nonmandatory Appendix B, para. B-1 for thread tensile stress area formulas.
50
ASME PCC-1–2022
NONMANDATORY APPENDIX I
INTERACTION DURING TIGHTENING
DELETED
51
ð 22 Þ
ASME PCC-1–2022
ð 22 Þ
NONMANDATORY APPENDIX J
OPTIONAL PRACTICES FOR FLANGE JOINT ASSEMBLY
J-1 INTRODUCTION
torque, disassemble the j oint and locate the source of
the problem.
The assembly procedure may include the optional
assembly practices described in this Appendix, in addition
to those described in section 1 0 and Nonmandatory
Appendix F.
J-3 BOLT ELONGATION (BOLT STRETCH)
MEASUREMENT
Bolt elongation measurement is the measurement ofthe
bolt’s change in length. Bolt elongation measurement is
typically completed by measuring the initial bolt length
and comparing it to the final bolt length after tightening.
If ultrasonic or micrometer measurement methods are
used, the following items should be considered during the
measurement:
(a) Compensation shall be made for temperature
changes in the bolt after the initial length measurement.
These temperature changes may be caused by factors such
as environmental changes or incidental friction during the
tightening process.
(b) For accuracy, the instrument should be calibrated
to properly read the bolts being tightened.
(c) For bolts constructed with a centerline indicator
(gauge) rod, neither initial length measurements nor
temperature compensation is required, thereby allowing
direct determination of the true bolt elongation (and
hence bolt stress) for both initial assembly and troubleshooting purposes during operation.
Ifbolt elongation (bolt stretch) measurement is selected
as the load-control technique, the following equation may
be used to calculate the bolt elongation:
J-2 MEASUREMENT OF GAPS
The primary purpose for measuring the gap between
flanges is to verify parallelism to ensure even gasket
compression before, during, and after tightening or
leak-mitigation troubleshooting (see Nonmandatory
Appendix P).
T h e o wn e r d e te rm i n e s wh e n m e a s u re m e n t a n d
recording are required. The assembler should consider
the final gap closure alignment for all joints.
The assembler should control the gaps between the
flanges of all critical service j oints (see M andatory
App endix I ) . The as s embler may o mit detailed gap
measurement and adj ustment for intermediate and
mild service applications but should maintain parallelism
of flange surfaces on all joints as a best practice.
Gap measurements are not intended to be indicators of
gasket stress. For gap measurements to have validity,
fl an ge s s h o u l d co n fo rm to th e fl atn e s s s tan d ard s
shown in Nonmandatory Appendix D, Table D-2 -1 M/
Table D-2-1. If gap measurement is required, the assembly
procedure should include the following instructions:
(a) Measure the gap between flanges at eight or more
equally spaced locations of good-quality flange surface
around the circumference.
(b) Label where the measurements are taken so that
subsequent measurements are taken at the same points.
(c) Use a measuring device, such as Vernier calipers or a
tapered wedge gauge, that allows for practical comparison
between points.
(d) During initial tightening, ensure measurements are
within 0.25 mm (0.010 in.) of one another.
(e) Loosen bolts in the vicinity of the low readings (the
smallest gap between flanges) until the gap is uniform to
within 0.25 mm (0.010 in.).
(f) If necessary, tighten bolts at the location of the
highest readings (the largest gap between flanges) .
However, if the difference in torque required to keep
the gap unifo rm i s greater than 5 0 % o f the target
L
i Sb
= jjj
k
× Leff yz jij A r zyz
E
zz jj
zz
j
z
{ k A ts {
where
A r = ro o t are a, m m 2 (i n. 2 ) (s e e N o n m an d ato ry
Appendix H for bolt root areas).
A ts = t e n s i l e s t r e s s a r e a , m m 2 ( i n . 2 ) ( s e e
N o nmandato ry Ap p endix H fo r b olt tens ile
stress areas).
E = modulus of elasticity, MPa (ksi).
L eff = effective stretching length, mm (in.). The conventional assumption is that the effective stretching
length in a through-bolted j oint system is the
di s tance b e twe e n th e mi dthi ckne s s o f the
nuts, where the nominal thickness of a heavy
hex series nut is one nominal bolt diameter.
By the same standard, the effective length of
52
ASME PCC-1–2022
the portion of a bolt that is studded into a tapped
hole is one-half of a nominal bolt diameter.
Sb = target bolt stress (root area), MPa (ksi).
A risk assessment of the proposed start-up retorque
operation should be carried out to establish that the
operation can be performed safely. Start-up retorque
should not be considered the same as live tightening
or single-stud replacement. Live tightening or singlestud replacement are post-assembly activities usually
undertaken due to leakage or maintenance requirements
and are covered further in ASME PCC-2.
NOTE: Bolt stresses computed in accordance with
ASM E B PVC , Section VI I I , D ivision 1 , M andatory
Appendix 2 are based on root area. If target bolt
stress (tensile stress area) is used, drop the A r/ A ts
term from the Δ L computation.
Δ L = bolt elongation (bolt stretch), mm (in.). The user
should select a tolerance on this computed value
and include it in the joint assembly procedure.
J-5 GROUPED BOLTING FOR LARGE FLANGES
Grouped bolting is the practice of grouping sets of adjacent bolts together and treating the sets as if they were
individual bolts for patterned tightening purposes. The
p ractice reduces unneces s ary to o l mo vements and
avoids p otentially o verstressing individual bo lts in
large-diameter flanges with many bolts (usually 36 or
m o re ) . F i gu re J - 5 - 1 i l l u s tra te s th e b o l t- gro u p i n g
concept for a 48-bolt flange.
J-4 START-UP RETORQUE
On joints that are problematic or that have been determined to have an insufficient buffer against leakage in
accordance with Nonmandatory Appendix O, a start-up
retorque may be specified to decrease the likelihood of
leakage during operation. 1
Start-up retorque is performed when the temperature
of the flange or bolts is between 150°C (300°F) and 230°C
(450°F) or within 24 h of unit start-up if the joint temperature remains below 1 5 0°C (3 00°F) . This temperature
range and time window are selected to allow for the
maximum amount of gasket relaxation prior to retightening while avoiding significant evaporation of lubricating
oils from the antiseize product. Loss of lubricating oils
greatly reduces the accuracy of the torque. The applied
torque is sometimes adjusted to account for changes in
antiseize nut factor at the average start-up retorque
temperature. Where start-up retorque is not practical,
live tightening at a later stage of operation using turnof-nut may be used as an alternative.
Start-up retorque is typically not recommended for
PTFE-based gaskets. However, pre-start-up retorque at
ambient temperature is encouraged for PTFE-based
gaskets to offset gasket creep from cold flow.
If a start-up retorque is required, the following instructions should be included in the assembly procedure:
(a) Adjust the ambient-temperature assembly target
torque value to account for any change in nut factor
with temperature.
(b) Once the unit is brought online and the metal
te mp e rature is b etwe en 1 5 0 ° C (3 0 0 ° F) and 2 3 0 ° C
(450°F) (commence once the flange reaches the lower
temperature) or within 2 4 h of a unit start-up if the
j o i n t te m p e ra tu re re m a i n s b e l o w 1 5 0 ° C ( 3 0 0 ° F ) ,
tighten each bolt, proceeding in a circular pattern. The
use ofmultitool tightening on opposing bolts is acceptable,
but use a circular pattern.
(c) Continue tightening in the circular pattern until the
nuts no longer turn.
J-6 ALTERNATIVE LEGACY CROSS-PATTERN
TIGHTENING SEQUENCE AND BOLTNUMBERING SYSTEM
As mentioned in Nonmandatory Appendix F, it may be
desirable to identify bolt locations around the flange, e.g.,
to help reference leak locations. Table J-6-1 is an acceptable option (see ASME PCC-1–2019, Table 3).
J-7 CONTROLLED DISASSEMBLY
J-7.1 General
For problematic joints, it may help to gradually reduce
stud load in multiple passes. One method to accomplish
this is using turn-of-nut principles.
J-7.2 Turn-of-Nut Disassembly Example
Step 1 . Loosen one bolt completely. Note the total nut
turn required to fully relieve the bolt load from assembled
to the finger-tight condition.
Step 2. Retighten the loose bolt to 7 ∕8 ofthe total nut turn
noted in Step 1.
Step 3. In a circular pattern, loosen each bolt by 1 ∕8 ofthe
total nut turn noted in Step 1.
NOTE: For problematic joints, perform Step 3 twice.
Step 4. Proceed with nut loosening in a circular pattern,
removing all load on each stud.
NOTE: If a stud starts galling during final disassembly, retighten
all loosened bolts (if possible) to the position obtained prior to
Step 4 and then recommence at Step 3.
1
Ifjoint-tightening activities are performed on pressurized equipment,
there is a risk of gasket blowout due to the disruption of the joint. Gasket
blowout or leakage may occur at a location around the periphery ofa joint
other than the one being tightened. This risk should be considered, particularly with respect to personnel in the vicinity of the joint.
53
ASME PCC-1–2022
Figure J-5-1
Example of Bolt Grouping for a 48-Bolt Flange
Group
12
Group
11
45
46
47
Group
1
48
1
End
44
2
3
4
Start
Group
2
5
43
6
42
7
41
8
40
Group
10
9
39
10
38
11
37
12
36
13
35
Group
9
Group
3
14
34
15
33
16
32
17
31
Group
8
18
30
19
29
28
20
27
26
Group
7
25
24
23
21
22
Group
4
Group
Bolts
1
2
3
4
5
6
7
8
9
10
11
12
1 -2-3-4
5-6-7-8
9-1 0-1 1 -1 2
1 3-1 4-1 5-1 6
1 7-1 8-1 9-20
21 -22-23-24
25-26-27-28
29-30-31 -32
33-34-35-36
37-38-39-40
41 -42-43-44
45-46-47-48
Treat the 1 2 groups as
if they were single
bolts. That is, tighten
all bolts in a group
before proceeding to
the next group in the
pattern. Follow
incremental steps per
the Star sequence in
Table F-6.1 .1 .1 -1 as if
this were a 1 2-bolt
pattern.
Group
5
Group
6
GENERAL NOTE: This figure is an illustration of how bolts may be grouped for tightening. Each group is treated as one bolt in the tightening
pattern. A suggested number of bolts for a group is the number contained within a 30-deg arc. However, the assembler should assess the potential
gasket damage or flange misalignment when grouping bolts and should consider adjusting the group size to prevent these issues.
54
ASME PCC-1–2022
Table J-6-1
Legacy Cross-Pattern Tightening Sequence and Bolt-Numbering System When Using a Single Tool
No. of
Bolts
Tightening Sequence for Cross-Pattern Passes
4
1, 3, 2, 4
8
1-5-3-7 → 2-6-4-8
12
1-7-4-10 → 2-8-5-11 → 3-9-6-12
16
1-9-5-13 → 3-11-7-15 → 2-10-6-14 → 4-12-8-16
20
1-11-6-16 → 3-13-8-18 → 5-15-10-20 → 2-12-7-17 → 4-14-9-19
24
1-13-7-19 → 4-16-10-22 → 2-14-8-20 → 5-17-11-23 → 3-15-9-21 → 6-18-12-24
28
1-15-8-22 → 4-18-11-25 → 6-20-13-27 → 2-16-9-23 → 5-19-12-26 → 7-21-14-28 → 3-17-10-24
32
1-17-9-25 → 5-21-13-29 → 3-19-11-27 → 7-23-15-31 → 2-18-10-26 → 6-22-14-30 → 4-20-12-28 → 8-24-16-32
36
1-2-3 → 19-20-21 → 10-11-12 → 28-29-30 → 4-5-6 → 22-23-24 → 13-14-15 → 31-32-33 → 7-8-9 → 25-26-27 → 16-17-18 → 34-35-36
40
1-2-3-4 → 21-22-23-24 → 13-14-15-16 → 33-34-35-36 → 5-6-7-8 → 25-26-27-28 → 17-18-19-20 → 37-38-39-40 → 9-10-11-12 →
29-30-31-32
44
1-2-3-4 → 25-26-27-28 → 13-14-15-16 → 37-38-39-40 → 5-6-7-8 → 29-30-31-32 → 17-18-19-20 → 41-42-43-44 → 9-10-11-12 →
33-34-35-36 → 21-22-23-24
48
1-2-3-4 → 25-26-27-28 → 13-14-15-16 → 37-38-39-40 → 5-6-7-8 → 29-30-31-32 → 17-18-19-20 → 41-42-43-44 → 9-10-11-12 →
33-34-35-36 → 21-22-23-24 → 45-46-47-48
52
1-2-3-4 → 29-30-31-32 → 13-14-15-16 → 41-42-43-44 → 5-6-7-8 → 33-34-35-36 → 17-18-19-20 → 45-46-47-48 → 21-22-23-24 →
49-50-51-52 → 25-26-27-28 → 9-10-11-12 → 37-38-39-40
56
1-2-3-4 → 29-30-31-32 → 13-14-15-16 → 41-42-43-44 → 21-22-23-24 → 49-50-51-52 → 9-10-11-12 → 37-38-39-40 → 25-26-27-28
→ 53-54-55-56 → 17-18-19-20 → 45-46-47-48 → 5-6-7-8 → 33-34-35-36
60
1-2-3-4 → 29-30-31-32 → 45-46-47-48 → 13-14-15-16 → 5-6-7-8 → 37-38-39-40 → 21-22-23-24 → 53-54-55-56 → 9-10-11-12 →
33-34-35-36 → 49-50-51-52 → 17-18-19-20 → 41-42-43-44 → 57-58-59-60 → 25-26-27-28
64
1-2-3-4 → 33-34-35-36 → 17-18-19-20 → 49-50-51-52 → 9-10-11-12 → 41-42-43-44 → 25-26-27-28 → 57-58-59-60 → 5-6-7-8 →
37-38-39-40 → 21-22-23-24 → 53-54-55-56 → 13-14-15-16 → 45-46-47-48 → 29-30-31-32 → 61-62-63-64
68
1-2-3-4 → 37-38-39-40 → 21-22-23-24 → 53-54-55-56 → 9-10-11-12 → 45-46-47-48 → 29-30-31-32 → 61-62-63-64 → 17-18-19-20
→ 57-58-59-60 → 33-34-35-36 → 5-6-7-8 → 41-42-43-44 → 13-14-15-16 → 49-50-51-52 → 25-26-27-28 → 65-66-67-68
55
ASME PCC-1–2022
NONMANDATORY APPENDIX K
NUT FACTOR CALCULATION OF TARGET TORQUE
ð 22 Þ
K-1 COMMON TARGET TORQUE FORMULA
Th e s e vari ab l e s are s i gni fi cant and s h o ul d no t b e
ignored when selecting the lubricant and determining
the nut factor (refs. [2] –[5] ).
A lubricant in combination with stud material and coatings will have a specific nut factor. A change to the
fastening system will change the nut factor, and the
torque values will need to be adj usted accordingly.
Users should use test results from nut factor trials that
are similar to their own conditions (lubrication, bolt material, b o lt diameter, b o lt and nut co ating, as s emb ly
temperature) or conduct their own nut factor trials.
Nut factor trials can be conducted by applying torque
to a bolt and measuring the obtained bolt load using a
calibrated load cell or instrumented bolt or calibrated
ultrasonic measurement.
The manufacturer’s maximum temperature for a given
lubrication product has not been a reliable indicator that
the product improves the joint’s disassembly after operation at an elevated temperature. Typically, the maximum
temperature is listed as the melting point or degradation
point ofthe solid with the highest temperature in the lubricant and is not a reflection of how the lubricant works at
that higher temperature. Users should obtain test results
on similar materials and in similar operating conditions to
guide them in selecting the appropriate product for that
service.
A common method for calculating target torque is to use
the nut factor:
(SI Units)
(U.S.
T = KDF /1 000
Customary Units)
T = KDF /1 2
where
D =
F=
K=
T=
(K-1M)
(K-1)
nominal diameter of the bolt, mm (in.)
target bolt load, N (lb)
nut factor (see para. K-1.1)
target torque, N·m (ft-lb)
K-1.1 Nut Factor, K
The nut factor, K, is an experimentally determined
dimensionless constant related to the coefficient of friction. The value of K in most applications at ambient
temperature is considered to be approximately equal
to the coefficient of friction plus 0.04 (ref. [1] ) (e.g., coefficient of friction = 0.16; nut factor = 0.16 + 0.04 ~ 0.20).
Published tables of experimental nut factors are available
from several sources; however, care should be taken to
understand the factors for the application being considered. Typical nut factors for industrial pressure vessel and
piping applications using ASME SA-193 low-alloy steel
bolts range from 0.16 to 0.23 at ambient temperature.
K-2 ADDITIONAL INFORMATION ON TARGET
TORQUE FORMULAS
Additional information on torque formulas and the
effect of friction factors may be found in the Handbook
of Bolts and Bolted Joints (ref. [1] ) . Chapter 3 provides
detailed formulas. Chapters 12 and 32 provide substantial
additional theoretical and experimental information and
equations, including eq. (K-2) shown in this Appendix.
Equation (K-2) applies to standard 60-deg thread angle
fasteners. It reflects the three specific resistance components: the thread pitch, the thread coefficient of friction,
and the nut face coefficient of friction. This approach has
been used in EN 1591-1, ISO 27509, and VDI 2230. Long
experience has shown the nut factor method to be equally
effective as the more complex formulas. While the nut
facto r me tho d do e s no t addre s s al l o f th e to rque preload relationship variables, it produces similar and
fully acceptable values for the assembly of flanges.
K-1.2 Effects of Changes in Nut Factor
It is important to understand the sensitivity of the
obtained load to an applied torque from changes in
nut factor. For example, a small change in nut factor
from 0.1 0 to 0.3 0 does not result in a 2 0% change in
torque but a 200% change.
Insufficient application of lubricant to the working
surfaces adds significant variability to the obtained
bolt load. Research has shown that the nut factor is dependent on lubrication, bolt material, bolt diameter, bolt and
nut coating, and assembly temperature. In tests using one
lubricant at ambient temperature [0°C to 40°C (32°F to
1 0 0 ° F) ] , the nut facto r was fo und to vary b y 5 0 %
(from 0.1 5 5 to 0.1 05 ) . In addition, in material tests,
ASM E SA-1 9 3 B8M bolts have been found to have a
3 0 % higher nut factor than ASM E SA-1 9 3 B 7 bolts.
56
ASME PCC-1–2022
μn
μt
For completeness, the mathematical model is given
here:
ip
y
d
T = F jjjj + t 2 + De n zzzz
2
cos
k
The target bolt load, F, can be determined from
(K-2)
F = A s yP%
{
This can be simplified for metric and Unified thread
forms to
T= F
i
jj
jj 0.1 5915
k
p+
0.57735
where
As
= tensile stress area of the thread, mm 2 (in. 2 ) (see
Nonmandatory Appendix H)
P% = percentage utilization factor for material yield
strength (default value typically 50%; i.e., P%
= 0.5)
σy = minimum yield strength of the bolt material,
N/mm 2 (lb/in. 2 )
De n yz
t d2 + 2 zzz
{
or more approximately (from VDI 2230) to
i
T = Fjjjj 0.16p +
k
0.58
t d2 +
= coefficient of friction for the nut face or bolt head
= coefficient of friction for the threads
De n yz
zz
2 z{
K-3 REFERENCES
NOTE:
[1] Bickford, J. H., Handbook of Bolts and Bolted Joints,
Marcel Dekker, Inc., New York (1995), p. 233
[2] Brown, W., “Efficient Assembly of Bolted Joints,” ASME
2 0 0 4 P re s s u re Ve s s e l s a n d P i p i n g C o n fe re n c e ,
PVP2 0 0 4- 2 6 3 5 , S an D iego , C A, J uly 2 5 –2 9 , 2 0 0 4,
DOI: 10.1115/PVP2004-2635
[3] Brown, W., Marchand, L., Evrard, A., and Reeves, D.,
“Effect of Bolt Size on Assembly Nut Factor,” ASME
2 0 0 7 P re s s u re Ve s s e l s a n d P i p i n g C o n fe re n c e ,
PVP2007-26644, San Antonio, TX, July 22–26, 2007,
DOI: 10.1115/PVP2007-26644
[4] Brown, W., and Lim, T., “The Effect of Bolt Size on the
Assembly Nut Factor,” ASME 2015 Pressure Vessels and
Piping Conference, PVP2015-45945, Boston, MA, July
19–23, 2015, DOI: 10.1115/PVP2015-45945
[5] Brown, W., and Long, S., “Factors Influencing Nut Factor
Test Results,” ASME 2017 Pressure Vessels and Piping
Conference, PVP2017-65506, Waikoloa, HI, July 16–20,
2017, DOI: 10.1115/ PVP2017-65506
• 0.16 p is the torque to stretch the bolt.
• 0.58 μ td2 is the torque to overcome thread friction.
D
• e n is the torque to overcome face friction.
2
where
De = effective bearing diameter of the nut face, mm
(in.)
x = (do + di)/2
d2 = basic pitch diameter of the thread, mm (in.) (For
metric threads, d2 = d − 0.6495 p ; for inch threads,
d2 = d − 0.6495/n .)
di = inner bearing diameter of the nut face, mm (in.)
do = outer bearing diameter of the nut face, mm (in.)
F = target bolt load, N (lb)
n = number of threads per inch, in. −1 (applies to inch
threads)
p = pitch of the thread, mm (For inch threads, this is
normally quoted as threads per inch, n ; i.e., p = 1/
n .)
T = target torque, N·mm (in.-lb)
β = half included angle for the threads, deg (i.e., 30
deg for metric and Unified threads)
57
ASME PCC-1–2022
NONMANDATORY APPENDIX L
ASME B16.5 FLANGE BOLTING INFORMATION
See Table L-1.
Table L-1
ASME B16.5 Flange Bolting Information
Flange Size
(NPS)
Class 150
Class 300
Class 400
Class 600
Class 900
#
#
#
#
#
Size
Size
Size
Size
Size
Class 1500
#
Size
Class 2500
#
Size
1
∕2
4
1
∕2
4
1
∕2
4
1
∕2
4
1
∕2
4
3
∕4
4
3
∕4
4
3
∕4
3
∕4
4
1
∕2
4
5
∕8
4
5
∕8
4
5
∕8
4
3
∕4
4
3
∕4
4
3
∕4
∕8
4
7
∕8
4
7
∕8
∕8
4
7
∕8
4
1
1
4
1
4
1 ∕8
1
4
1
∕2
4
5
∕8
4
5
∕8
4
5
∕8
4
7
1 1 ∕4
4
1
∕2
4
5
∕8
4
5
∕8
4
5
∕8
4
7
1 ∕2
1
4
1
∕2
4
3
∕4
4
3
∕4
4
3
∕4
4
2
4
5
∕8
8
5
∕8
8
5
∕8
8
5
∕8
8
4
5
8
3
8
3
8
3
∕4
8
8
3
8
3
8
3
∕4
8
∕8
∕8
1
1
2 ∕2
∕8
∕4
∕4
4
5
1
3 ∕2
8
5
∕8
8
3
∕4
8
7
∕8
8
7
4
8
5
∕8
8
3
∕4
8
7
∕8
8
7
5
8
3
∕4
8
3
∕4
8
7
∕8
8
6
8
3
∕4
12
3
∕4
12
7
∕8
12
1
8
8
3
∕4
12
7
∕8
12
1
12
1 1 ∕8
10
12
7
∕8
16
1
16
1 1 ∕8
16
12
12
7
∕8
16
1 1 ∕8
16
1 1 ∕4
14
12
1
20
1 1 ∕8
20
16
16
1
20
1 1 ∕4
18
16
1
1 ∕8
20
20
1 1 ∕8
24
20
1 1 ∕4
3
∕8
∕4
∕4
7
7
1
∕8
8
∕8
8
1
1
8
1
8
1 ∕8
∕8
8
1
1 ∕8
8
1 1 ∕4
…
…
…
…
…
…
8
1 1 ∕8
8
1 1 ∕4
8
1 1 ∕2
8
1 1 ∕4
8
1 1 ∕2
8
1 3 ∕4
2
7
12
1
1 ∕8
12
1 ∕8
8
12
1 3 ∕8
12
1 5 ∕8
12
2
1 1 ∕4
16
1 3 ∕8
12
1 7 ∕8
12
2 1 ∕2
20
1 1 ∕4
20
1 3 ∕8
16
2
12
2 3 ∕4
1 1 ∕4
20
1 3 ∕8
20
1 1 ∕2
16
2 1 ∕4
…
…
20
1 3 ∕8
20
1 1 ∕2
20
1 5 ∕8
16
2 1 ∕2
…
…
24
1
1 ∕4
24
3
1 ∕8
20
5
1 ∕8
20
7
1 ∕8
16
3
2 ∕4
…
…
24
1 1 ∕4
24
1 1 ∕2
24
1 5 ∕8
20
2
16
3
…
…
24
1 1 ∕2
24
1 3 ∕4
24
1 7 ∕8
20
2 1 ∕2
16
3 1 ∕2
…
…
58
3
1
ASME PCC-1–2022
NONMANDATORY APPENDIX M
WASHER USAGE GUIDANCE AND PURCHASE SPECIFICATIONS
FOR THROUGH-HARDENED WASHERS
ð 22 Þ
M-1 WASHER USAGE GUIDANCE
M-1.4 Existing Standards
M-1.1 Usage
Washers in accordance with ASTM F436 have been used
previously on piping flanges. However, the use of ASTM
F436 washers may lead to interference with the spot face/
back facing on the flanges. Also, ASTM F43 6 does not
provide dimensions for certain nominal sizes needed
for pip e or vessel flanges. The intent of the Type 1
washer in this Appendix is to specify a washer of the
same general material as an ASTM F43 6 washer but
with revis ed dimensio ns to make them co mp atib le
with pipe or vessel flanges.
The use of washers on pressure boundary bolted flange
joints is optional. However, it is generally recognized that
the use of through-hardened steel washers will improve
the translation of torque input into bolt preload by
providing a smooth and low-friction bearing surface
for the nut.
Washers protect the contact surface of the flange from
damage caused by a turning nut. These are important
considerations when torquing methods (either manual
or hydraulic) are used for bolt tightening.
This Appendix specifies the procurement of throughhardened was hers fo r b o lted flange j o ints co vered
within the scope of this Standard. The use of surfacehardened washers is not recommended since the soft
interior material under direct compression will flow plastically, causing washer cupping and thinning with the
associated reduction in preload.
M-1.5 Previous Material
Figures 1 and 2 in the original edition of ASME PCC-1
referenced ASME SA-540 for the manufacture of washers
for elevated temperatures . This Ap pendix does not
continue the use of this material due to material cost
and manufacturing concerns. D iscontinuation of the
use of SA-540 material does not imply that this material
is technically deficient.
M-1.2 Dimensions
The outside diameter of the washers detailed in this
Appendix was selected to enable their use on flanges
with spot faces or back facing meeting the requirements
ofstandard ISO 7005-1 for metric flanges and MSS SP-9 for
inch flanges.
The inside diameter of these washers was selected to
enable their use under the nut. Use of these washers under
the head of a bolt may lead to interference with the bolt
shank or underhead fillet.
Table M-1.3-1
Recommended Washer Temperature Limits
Material Type
M-1.3 Washer Temperature
Reuse [Note (2)]
1
425°C (800°F) [Note (3)]
205°C (400°F)
4
540°C (1,000°F)
400°C (750°F)
5
650°C (1,200°F)
425°C (800°F)
6
815°C (1,500°F)
550°C (1,025°F)
7
Washer temperature limits are shown in Table M-1.3-1.
Note that in operation, actual bolting (studs, nuts, and
washers) temperature may be lower than process fluid
temperature.
For uninsulated j oints, ASME B31.3 considers flange
bolting temperature to be 80% of fluid temperature.
Single-Use [Note (1)]
...
...
NOTES:
(1) Single-use temperature limits are based on replacement whenever the existing washer has been exposed to a temperature in
excess of the corresponding reuse limit.
(2) Reuse temp erature limits are b ased on not exceeding the
tempering temperature of the particular material such that
the material is not subject to annealing (softening).
(3) Field experience indicates that the use of Type 1 material at
temperatures above 315°C (600°F) can lead to difficulty at disassembly due to galling between washer and nut as a result of softening of the washer.
59
ASME PCC-1–2022
M-1.6 Material Application
M-2.3.2 Washers up to and including 100 mm (4 in.)
nominal size shall be through-hardened, except Type 7
material. 1
Types 1 and 4 washer materials are intended for use
with steel fasteners such as Grade 2H, 4, or 7 steel nuts per
ASME SA-194. The Type 4 washer material is an alloy steel
with a higher temperature limit. Types 5 and 6 washer
materials are intended for use with austenitic steel
fasteners s uch as Grade 8 aus tenitic steel nuts p er
ASME SA-194. The Type 6 washer material is a precipitation hardening stainless steel that has increased corrosion
resistance as compared to Type 5 washer material. Type 7
washer material is intended for use with austenitic steel
fasteners such as Grade 8 nuts per ASME SA-194 in lowtemperature applications where other materials may
become brittle. For the purposes of this Appendix, lowte m p e r a tu r e a p p l i c a ti o n s r e fe r to te m p e r a tu r e s
between −45°C (−50°F) and −185°C (−300°F).
M-2.3.3
tures
(a)
(b)
(c)
(d)
M-2.4 Chemical Composition
Washers shall conform to the chemical composition
specified in Table M-2.4-1.
M-2.5 Mechanical Properties
Types 1, 4, and 5 washers shall have a hardness of 38
HRC to 45 HRC. Type 6 washers shall have a hardness of33
HRC to 42 HRC. Type 7 washers shall have a hardness of20
HRC to 23 HRC.
M-1.7 Installation
To avoid any concerns about the effect of washer markings on the performance ofthe washer to nut interface, it is
recommended that these washers be installed with the
marked face toward the flange surface.
M-2.6 Dimensions and Tolerances
M-2.6.1 Washers shall conform to the dimensions
shown in Table M-2.6.1-1 or Table M-2.6.1-2 with tolerances shown in Table M-2.6.1-3 or Table M-2.6.1-4 as applicable.
M-2 PURCHASE SPECIFICATION FOR THROUGHHARDENED WASHERS
M-2.1 Scope
M-2.6.2 Washers shall have a multidirectional lay with
a surface roughness not exceeding 3.2 μm (125 μin.) in
height including any flaws in or on the surface. Surface
roughness shall be as defined in ASME B46.1.
M-2.1.1 This Appendix covers the chemical, mechanical, and dimensional requirements for through-hardened
steel washers for use with fasteners having nominal sizes
of 14 mm to 100 mm and 1 ∕2 in. to 4 in. These washers are
intended for use on pressure-containing flanges with bolts
or studs and nuts. These washers are suitable for use with
low-alloy steel and austenitic steel fasteners covered in
ASME SA-193 and ASME SA-194.
M-2.1.2
(a)
(b)
(c)
(d)
(e)
Type
Type
Type
Type
Type
Minimum tempering (precipitation) temperashall be as follows:
for Type 1, 205°C (400°F)
for Type 4, 370°C (700°F)
for Type 5, 425°C (800°F)
for Type 6, 550°C (1,025°F)
M-2.7 Workmanship, Finish, and Appearance
Washers shall be free of excess mill scale, excess coatings, and foreign material on bearing surfaces. Arc and gas
cut washers shall be free of metal spatter.
M-2.8 Sampling and Number of Tests
The types of washers covered are
1 — carbon steel
4 — low-alloy steel
5 — martensitic steel
6 — precipitation hardening steel
7 — austenitic steel
M-2.8.1 A lot of washers shall consist of all material
offered for inspection at one time that has the following
common characteristics:
(a) same nominal size
(b) same material grade
(c) same heat treatment
M-2.2 Ordering Information
M-2.8.2 From each lot described in para. M-2.8.1, the
number of specimens tested for each required property
shall be as specified in Table M-2.8.2-1.
O rders for washers under this sp ecification shall
include the following:
(a) nominal size
(b) type (see para. M-2.1.2)
(c) quantity (number of pieces)
M-2.3 Materials and Manufacture
M-2.3.1 Steel used in the manufacture of washers shall
be produced by the open-hearth, basic-oxygen, or electricfurnace process.
1
Type 7 material is an austenitic steel that does not harden through
heat treatment. This alloy derives galling resistance through chemical
composition rather than hardness.
60
ASME PCC-1–2022
Table M-2.4-1
Chemical Requirements
M-2.9.2
Hardness tests shall be performed in accordance with the Rockwell test method specified in ASTM
F606/F606M.
Composition, % max.
Washer Type
Phosphorus
Sulfur
1
0.050
0.060
4 [Note (1)]
0.040
0.050
5 [Note (2)]
0.040
0.030
6 [Note (3)]
0.040
0.030
7 [Note (4)]
0.060
0.030
M-2.10 Decarburization
M-2.10.1
Washers shall meet the following limits for
decarburization after completion of all manufacturing
operations:
(a) maximum depth of free ferrite: 0.08 mm (0.003 in.)
(b) maximum total affected depth (free ferrite plus
partial decarburization): 0.20 mm (0.008 in.)
NOTES:
(1) Type 4 low-alloy steel washers shall be manufactured from SAE
number 4130 or 4140 steel listed in ASTM A829.
(2) Type 5 martensitic steel washers shall be manufactured from UNS
S41000 steel listed in ASTM A240.
(3) Type 6 precipitation hardening steel washers shall be manufactured from UNS S17400 steel listed in ASTM A693.
(4) Type 7 austenitic steel washers shall be manufactured from UNS
S21800 steel listed in ASTM A240.
M-2.10.2
Decarburization testing shall be performed
in accordance with SAE J419.
M-2.11 Product Marking
M-2.11.1
Washers shall be marked with a symbol, or
other distinguishing marks, to identify the manufacturer
or private label distributor, as appropriate.
M-2.11.2
Washers shall be marked with the type, “1,”
“4,” “5,” “6,” or “7,” as applicable.
M-2.11.3
All markings shall be depressed and located
on the same face of the washer.
M-2.9 Test Methods: Hardness
M-2.9.1
A minimum of two readings shall be taken 180
deg apart on at least one face at a minimum depth of 0.38
mm (0.015 in.).
61
ð 22 Þ
ASME PCC-1–2022
Table M-2.6.1-1
Dimensional Requirements for Metric Washers
I
.D.
Table M-2.6.1-2
Dimensional Requirements for U.S. Customary Washers
O.D.
I
.D.
O.D.
T
Nominal
Size, mm
14
Outside Diameter, Inside Diameter,
O.D., mm
I.D., mm
28
15
T
Thickness,
T, mm
Outside
Diameter, O.D.
3
Nominal Size, in.
Inside
Diameter, I.D.
Thickness,
T
mm
in.
mm
in.
mm
in.
16
30
17
4
1
∕2
27.0
1.063
14.3
0.563
3.2
0.125
20
37
21
5
5
∕8
33.4
1.313
17.5
0.688
4.0
0.156
24
44
25
6
3
∕4
38.1
1.500
20.7
0.813
4.8
0.188
27
50
28
6
7
∕8
43.6
1.718
23.8
0.938
5.6
0.219
30
56
31
6
1
50.0
1.968
27.0
1.063
6.4
0.250
33
60
34
6
1 1 ∕8
54.8
2.156
30.2
1.188
6.4
0.250
1 1 ∕4
60.3
2.375
33.4
1.313
6.4
0.250
36
66
37
6
39
72
42
6
1 3 ∕8
65.9
2.593
36.5
1.438
6.4
0.250
42
78
45
6
1 1 ∕2
71.4
2.812
39.7
1.563
6.4
0.250
45
85
48
6
1 5 ∕8
77.8
3.062
42.9
1.688
6.4
0.250
48
92
52
6
1 3 ∕4
82.6
3.250
46.1
1.813
6.4
0.250
52
98
56
6
1 7 ∕8
87.3
3.438
49.2
1.938
6.4
0.250
56
105
62
6
2
93.7
3.688
54.0
2.125
6.4
0.250
2 1 ∕4
104.8
4.125
60.3
2.375
6.4
0.250
64
115
70
6
70
125
76
6
2 1 ∕2
115.9
4.563
66.7
2.625
6.4
0.250
76
135
82
6
3
2 ∕4
127
5.000
73.0
2.875
6.4
0.250
82
145
88
6
3
138.1
5.438
79.4
3.125
6.4
0.250
90
160
96
6
3 1 ∕4
149.2
5.875
85.7
3.375
6.4
0.250
95
165
101
6
3 1 ∕2
160.4
6.313
92.1
3.625
6.4
0.250
100
175
107
6
3 3 ∕4
173.1
6.813
98.4
3.875
6.4
0.250
4
182.6
7.188
104.8
4.125
6.4
0.250
GENERAL NOTE: Tolerances are as noted in Table M-2.6.1-3.
GENERAL NOTE: Tolerances are as noted in Table M-2.6.1-4.
62
ASME PCC-1–2022
Table M-2.6.1-3
Dimensional Tolerances for Metric Washers
Tolerance, mm, for Nominal Size of
14 mm Through 20 mm Through 30 mm Through 45 mm Through 82 mm Through
16 mm
27 mm
42 mm
76 mm
100 mm
Dimensional Characteristics
Inside diameter, I.D.
−0, +0.4
−0, +0.5
−0, +0.6
−0, +0.7
−0, +0.9
Outside diameter, O.D.
−1.3, +0
−1.6, +0
−1.9, +0
−2.2, +0
−2.5, +0
±0.15
±0.20
±0.20
±0.20
±0.20
Flatness (max. deviation from straight edge
placed on cut side)
0.25
0.30
0.40
0.50
0.80
Concentricity, FIM [Note (1)] (inside diameter
to outside diameter)
0.3
0.5
0.5
0.5
0.5
Burr height (max. projection above adjacent
washer surface)
0.25
0.40
0.40
0.50
0.65
Thickness,
T
NOTE: (1) Full indicator movement.
Table M-2.6.1-4
Dimensional Tolerances for U.S. Customary Washers
Tolerance for Nominal Size of
1 in. Through 1 1 ⁄2 in.
<1 in.
Dimensional Characteristics
mm
in.
mm
in.
>1 1 ⁄2 in. Through 3 in.
mm
in.
>3 in.
mm
in.
Inside diameter, I.D.
−0, +0.81
−0, +0.032
−0, +0.81
−0, +0.032
−0, +1.60
−0, +0.063
−0, +1.60
−0, +0.063
Outside diameter, O.D.
±0.81
±0.032
±0.81
±0.032
±1.60
±0.063
±1.60
±0.063
±0.13
±0.005
±0.13
±0.005
±0.13
±0.005
±0.13
±0.005
Flatness (max. deviation from straight 0.25
edge placed on cut side)
0.010
0.38
0.015
0.51
0.020
0.81
0.032
Concentricity, FIM [Note (1)] (inside 0.81
diameter to outside diameter)
0.032
0.81
0.032
1.60
0.063
1.60
0.063
Burr height (max. projection above
adjacent washer surface)
0.010
0.38
0.015
0.51
0.020
0.64
0.025
Thickness,
T
0.25
NOTE: (1) Full indicator movement.
Table M-2.8.2-1
Sampling
Number of Pieces in Lot
Number of Specimens
800 and under
1
801 to 8 000
2
8 001 to 22 000
3
Over 22 000
5
63
ASME PCC-1–2022
NONMANDATORY APPENDIX N
DEFINITIONS, COMMENTARY, AND GUIDELINES
ON THE REUSE OF BOLTS
ð 22 Þ
N-1 TERMS AND DEFINITIONS
(3) nut wall bending (nut becomes slightly conically
shaped due to higher radial loadings at first engaged
threads, thereby shifting some load to the adj acent
threads)
The bottom-line result of this load transfer from bolt to
nut is that the first threads of engagement are subjected to
a high unit loading since a major part of the load tends to
transfer through these first threads.
(e) Fro m the p revio us p o ints it can b e s een that
working and reworking the same threads in a proper
installation can be beneficial.
(1 ) In the case ofbolts with an integral head, it is very
simple to rework the same threads over and over from
assembly to assembly by simply properly installing the
same nut on the same bolt each time. Since the flange
determines the grip length (effective stretching length),
the same threads are always being worked.
(2) In the case of bolts without integral head, it is
virtually imp o s s ib le to wo rk and rewo rk the s ame
threads given the current workforce practices. When it
b eco mes neces s ary to reus e b o lts witho ut integral
heads, strict control is advised to ensure that the threaded
fasteners are correctly installed with some means of
determining that you are working the same threads. A
complete change of the nuts is also a step that may
create more uniformity.
(f) When using torque devices without a measurement
of load or elongation, determination of the friction condition of a fastener is difficult. However, creating similar and
fairly predictable conditions on a group of fasteners is
more practical. Starting with new threaded fasteners
and treati ng the m all the s ame is an effective and
common way to minimize load variability from bolt to bolt.
(g) Continuous reuse is an option when you have
adequately attended to the issues herein discussed.
(h) Ifan adequate bolt reuse system is used, it is advised
that the fasteners be periodically replaced based on the
following:
(1 ) operational fatigue or abuse, surface and/or integral inspections, mechanical integrity inspections, galling,
nut not running freely, difficult disassembly, or j oint
leakage.
(2) ifone bolt in a joint is replaced, it is recommended
that all bolts be replaced. If all bolts cannot be changed,
a n d m o r e th a n o n e b o l t i s c h a n ge d , s p a c e th e m
See Mandatory Appendix I.
N-2 GENERAL COMMENTARY
The following discussions are limited to site and field
application:
(a) Successful flange joint assembly is subject to a large
number of variables in both joint design and field conditions. The fastener system materials, quality, and condition have a large influence over the total outcome.
(b) While it is recognized that even new fasteners may
produce ±30% variation in bolt load when torqued, it is
also recognized that when properly installed and well
lubricated, the maj ority of the fasteners will produce
loads in the ±1 5 % variation range with many falling
into the ±1 0% variation range. This is why torque is
s uccess ful fo r many ap p lications . Keep ing as many
fasteners in the 10% to 15% variation range is very important.
(c) When the threads of new fasteners engage under
load, they wear on each other. The surfaces and friction
change and therefo re their p erfo rmance is fo rever
changed. D ry or poorly lubricated fasteners tend to
create higher friction conditions, while well-lubricated
fasteners tend to create lower friction conditions. Each
s ub s e q u e n t e n gage m e n t o f th e s a m e th re a d s wi l l
produce similar results until an optimum or minimum
condition occurs. Depending on the fastener size, the
load change may vary from a few hundred pounds to a
few thousand pounds.
(d) The axial compression of a nut, and the extension of
the bolt within the nut, have to be reconciled by means of
other types of deformation, since thread contact requires
the same deformation of nut and bolt along the bearing
surfaces of the two thread systems. The reconciling influences of this incompatible simple axial strain have been
identified to be
(1 ) thread bending (threads act as cantilevers)
(2) thread recession (lateral expansion of the nut
accompanying the compressive axial stress, plus lateral
expansion due to radial component of thread load)
64
ASME PCC-1–2022
symmetrically around the bolt circle so that they are
surrounded by old fasteners.
(i) Tightening methods that do not apply friction loads
to the threads during the lo ading p ro ces s , s uch as
hydraulic or mechanical tens io ning, usually do no t
have a detrimental effect on the threads due to the
lack of friction during the loading.
(j) While factors such as handling, transporting, and
storage are very important, suffice it to say that those
shall be done in a manner to preserve both the quality
and integrity of the fastener and fastener threads.
(k) Working with and reconditioning fasteners in the
field is expensive and unpredictable when compared to
the cost of new. Reconditioning/replacement considerations could include
(1 ) number of bolts to recondition
(2) availability of new bolts
(3) labor cost
(4) criticality of the bolted flange joint
(5) condition of previously applied coatings
the replacement cost and considered in the assessment of
critical issues of the assembly.
(b) Strong consideration should be given to replacing
bolts of any size should it be found that they have been
abused or nonlubricated during previous assemblies.
(c) Thread dies generally do not yield a highly cleaned
reconditioned surface; therefore, turning bolt threads in a
lathe is the p referred method to recondition costly
fasteners. Although preferred, this process will remove
thread material and tolerance limits specified in ASME
B1.1 must be maintained.
(d) Nuts are not generally reconditioned.
N-4 GUIDELINES FOR REUSE OF GASKETS
(a) Reuse of a gasket is not recommended. However,
grooved-metal gaskets may be reused after the substrates
have been reconditioned and refaced in a manner consistent with the original product specification. The reinstallation of gaskets so refurbished is not considered gasket
reuse since the sealing performance ofthe gasket has been
restored.
(b) Experience has clearly shown that only a new
gasket will reliably provide the necessary plastic deformation and elastic recovery characteristics essential to
achieve an effective seal. Visual or physical inspection
of a used gasket for apparent damage is not sufficient
to detect such sealing surface factors as work hardening,
brittleness, or the effects of heat or interaction with the
service fluid.
N-3 GUIDELINES FOR REUSE OF BOLTS AND NUTS
(a) When using bolts and nuts of common grade for
fasteners up to M30 (1 1 ∕8 in.) diameter, the use of new
bolts and nuts is recommended when bolt-load control
methods such as torque or tension are deemed necessary.
For larger diameters, it is recommended that the cost of
cleaning, deburring, and reconditioning be compared to
65
ð 22 Þ
ASME PCC-1–2022
NONMANDATORY APPENDIX O
ASSEMBLY BOLT STRESS DETERMINATION
O-1 INTRODUCTION
ð 22 Þ
The methodology outlined in this Appendix assumes
that th e gas ke ts b e i ng us e d unde rgo a re as o nab l e
amount (>1 5%) of relaxation during the initial stages
of operation, such that the effects of operational loads
in increasing the bolt stress need not be considered
(i.e., gasket relaxation will exceed any operational boltload increase) . In some rare cases, this may not be the
case, and the limits should then also be checked at
both the ambient and operating bolt stress and temperatures. For most standard applications, this will not be necessary.
In addition, the methodology is for ductile materials
(strain at tensile failure in excess of15%). For brittle materials, the margin between the specified assembly bolt
stress and the point of component failure may be considerably reduced and, therefore, additional safety factors
should be introduced to guard against such failure.
The method does not consider the effect of fatigue,
creep, or environmental damage mechanisms on either
the bolt or flange. These additional modes of failure
may also need to be considered for applications where
they are found and additional reductions in assembly
bolt stress may be required to avoid j oint component
failure.
O-1.1 Scope
This Appendix intends to provide guidance for the
determination of an appropriate assembly bolt stress
with due consideration for joint integrity. The detailed
procedures provided in this Appendix are intended for
flange j oints for which controlled assembly methods
are to be used. Provisions are made for two simple
approaches and a joint component approach.
The historic use ofa common single bolt stress across all
flange sizes and ratings [e.g., 345 MPa (50 ksi)] can result
in a gasket stress that does not provide sufficient margin to
overcome the effects of creep/relaxation, pressure/
external loads, and thermal loading. In addition, the
use of this bolt stress can result in either loading bolts
past their yield strength, as in the case of austenitic stainless steels, or loading flanges past their flange strength
limit, causing permanent flange deformation. For this
reason, the j oint component approach outlined in this
Appendix is preferred. However, for some sites, due to
their limited range of operating conditions and flange
configurations, the simpler gasket stress or single bolt
stress approaches may offer sufficient j oint integrity
and simpler site execution.
The calculations contained in this Appendix should be
used to assist in the selection of other aspects of j oint
assembly, such as the assembly method and whether additional steps, such as start-up retorque, are required. For
example, the calculations may indicate that the required
bolt load is close to the flange strength limit, which may
require the use of more accurate assembly methods and/
or the use of a start-up retorque to recover initial bolt load
relaxation. A smaller range of bolt load between the
minimum required and the maximum permissible indicates that greater care should be taken with assembly
method selection, assembly procedure selection, and
load control method.
O-1.3 Definitions
A b = bolt root area, mm 2 (in. 2 )
A g = gasket area [π/4 (GO.D. 2 − GI.D. 2 )] , mm 2 (in. 2 ) 1
GI.D. = larger of the gasket sealing element or flange
seating surface inner diameter, mm (in.)
GO.D. = smaller of the gasket sealing element or the
fl ange s e ati ng s urface o ute r di am e te r,
mm (in.)
K = nut factor (for bolt material, lubricant/antiseize, and temperature)
n b = number of bolts
Pmax = maximum design pressure, MPa (psi)
Sya = flange yield stress at assembly, MPa (psi)
Syo = flange yield stress at operation, MPa (psi)
Sb max = maximum permissible bolt stress, MPa (psi)
Sb min = minimum permissible bolt stress, MPa (psi)
Sb sel = selected assembly bolt stress, MPa (psi)
O-1.2 Cautions
The provisions of this Appendix consider that the ASME
PCC-1 guidelines for the j oint component condition
(flange surface finish, bolt spacing, flange rigidity, bolt
condition, etc.) are within acceptable limits.
1
Where a gasket has additional gasket area, such as a pass partition
gasket, which may not be as compressed as the main outer sealing
element due to flange rotation, a reduced portion of that area, such
as half the additional area, should be added to A g.
66
ð 22 Þ
ASME PCC-1–2022
Sfmax
Sgmax
Sgmin-O
Sgmin-S
SgT
Tb
Ti
θfmax
θgmax
ϕb
ϕg
ð 22 Þ
= maximum permissible bolt stress prior to
flange damage, MPa (psi)
= maximum permissible gasket stress, MPa
(psi)
= minimum gasket operating stress, MPa (psi)
= minimum gasket seating stress, MPa (psi)
= target assembly gasket stress, MPa (psi)
= assembly bolt torque, N·m (ft-lb)
= Target Torque Index based on a unit bolt
stress, N·m/MPa (ft-lb/ksi)
= single flange rotation at Sfmax, deg
= maximum permissible single flange rotation
fo r ga s ke t a t th e m a xi m u m o p e ra ti n g
temperature, deg
= bolt diameter, mm (in.)
= fractio n o f gas ket lo ad remaining after
relaxation
i mp ro ve d i n th e fi e l d b y co mp ari s o n to a s i mp l e r
method. Depending on the complexity of the joints in a
given p lant, a s imp le ap p ro ach (e. g. , s tandard b o lt
s tress p er s ize acro ss all standard flanges) may be
m o re e ffe cti ve i n p re ve nti ng l e akage th an a mo re
complex approach that includes consideration of the
integrity of all joint components.
This Appendix outlines two approaches: the simpler
single-assembly bolt stress approach (which is simpler
to use but may result in damage to j oint components)
and a more complex j oint component-based approach
that considers the integrity of each component.
O-3 SIMPLE APPROACH
O-3.1 Required Information
ð 22 Þ
In order to determine a standard assembly bolt stress
for a single joint or across all flanges, it is recommended
that, as a minimum, the target gasket stress, Sg T, for a given
gasket type be considered. Further integrity issues, as
outlined in section O-4 on the joint component approach,
may also be considered, as deemed necessary.
O-2 ASSEMBLY BOLT STRESS SELECTION
It is recommended that bolt assembly stresses be established with due consideration of the following joint integrity issues:
(a) Sufficient Gasket Stress to Seal the Joint. The
assembly bolt stress should provide sufficient gasket
stress to seat the gasket and sufficient gasket stress
during operation to maintain a seal.
(b) Damage to the Gasket. The assembly bolt stress
should not be high enough to cause overcompression
(physical damage) of the gasket or excessive rotation
of the flange, which might lead to localized gasket overcompression or damage to the flange sealing surface.
(c) Damage to the Bolts. The specified bolt stress should
be below the bolt yield point, such that bolt failure does not
occur. In addition, the life of the bolt can be extended by
specifying an even lower load. If hydraulic tensioners are
used for assembly, then the appropriate load loss factors,
per Nonmandatory Appendix Q, should be considered.
(d) Damage to the Flange. The assembly bolt stress
should be selected such that permanent deformation of
the flange does not occur. I f the flange is deformed
during assembly, it might leak during operation or successive assemblies might cause joint leakage due to excessive
flange rotation. Leakage due to flange rotation may be due
to the concentration of the gasket stress on the gasket
outer diameter causing damage or additional relaxation.
Another potential issue is the flange face outer diameter
touching, which reduces the effective gasket stress. If
hydraulic tensioners are used for assembly, then the
pass B load loss factors, per Nonmandatory Appendix
Q, should be considered against flange and gasket damage.
However, it is also important to consider the practicalities involved with the in-field application of the specified
bolt stress. If a different assembly stress is specified for
each flange in a plant, including all variations of standard
piping flanges, then it is unlikely, without a significant
assembly quality assurance plan, that success will be
O-3.2 Determining the Appropriate Bolt Stress
The appropriate bolt stress for a range of typical joint
configurations may be determined via eq. (O-1).
Sbsel
= SgT
Ag
nb A b
(O-1)
The average bolt stress across the joints considered may
then be selected and this value can be converted into a
torque value using eq. (O-2 M) for metric units or eq.
(O-2) for U.S. Customary units.
Tb = SbselK Ab b /1 000
(O-2M)
Tb = SbselK Ab b /1 2
(O-2)
As an alternative to these equations, Tables O-3.2-1M
and O-3.2-1 provide reference tables that tabulate Target
Torque Indices, Ti, based on eqs. (O-2M) and (O-2) using a
unit bolt stress (e.g., substituting a value of1 for Sb sel ), with
nut factors of 0.15, 0.18, and 0.2. The final assembly bolt
torque may then be obtained by using eq. (O-3 ) . An
example is shown in Notes (b) (2 ) and (b) (3) in Table
O-3.2-1M and Notes (b)(2) and (b)(3) in Table O-3.2-1.
The nut factors provided in Tables O -3 .2 - 1 M and
O-3.2 -1 represent examples and may vary from actual
values. Refer to Nonmandatory Appendix K for guidance
in determining nut factors.
If another bolt stress or nut factor is required, then the
table may be converted to the new values using eq. (O-3),
where Sb′sel , T′b , and K′ are the original values.
67
ð 22 Þ
ASME PCC-1–2022
Sb
Tb = K sel T b = Ti K Sbsel
K Sb sel
K
(e) The target assembly gasket stress, Sg T, should be
selected by the user considering user experience and
industry test data or in consultation with the gasket manufacturer. The target gasket stress is based on the full gasket
area and should be selected to be near the upper end of the
acceptable gasket stress range, as this will give the most
amount of buffer against joint leakage.
(f) The maximum assembly gasket stress, Sgmax, should
be obtained from industry test data or the gasket manufacturer. This value is the maximum compressive stress at
the assembly temperature, based on the full gasket area,
which the gasket can withstand without permanent
damage (excessive leakage or lack of elastic recovery)
to the gas ket s eali ng el ement. Any value p ro vi ded
should include consideration of the effects of flange rotation for the type of flange being considered in increasing
the gasket stress locally on the outer diameter.
(g) The minimum gasket seating stress, Sgmin-S, should
be obtained from industry test data or the gasket manufacturer. This value is the minimum reco mmended
compressive stress at the assembly temperature and is
based on the full gasket area. The value is the stress
that the gasket should be assembled to in order to
obtain adequate redistribution of any filler materials
into filler serrations and ensure an initial seal between
the gasket and the flange faces.
(h) The minimum gasket operating stress, Sg min- O ,
s ho ul d b e o b tained fro m indus try te s t data o r the
gasket manufacturer. This value is the minimum recommended compressive stress after offloading of the gasket
by operational loads and is based on the full gasket area.
This is the gasket stress that should be maintained on the
gasket during operation in order to ensure that leakage
does not occur.
(i) The gas ket relaxatio n fractio n, ϕ g , s ho uld b e
obtained from industry test data or the gasket manufacturer for the gasket in flange assemblies of similar configuration (geometry, dimensions, and rigidity) to the ones
being assessed. A default value of 0.7 may be used if data
are not available.
(O-3)
O-4 JOINT COMPONENT APPROACH
ð 22 Þ
O-4.1 Required Information
There are several values that should be known prior to
calculating the appropriate assembly bolt stress using the
joint component approach.
(a) The maximum permissible flange rotation, θgmax, at
the assembly gasket stress and the gasket operating
temperature should be obtained from industry test
data or from the gasket manufacturer. There is presently
no standard test for determining this value; however,
typical limits vary from 0 .3 deg for expanded PTFE
gaskets to 1 .0 deg for typical graphite-filled metallic
gaskets (per flange). A suitable limit may be determined
for a given site or application based on the calculation of
the amount of rotation that presently exists in flanges in a
given service using the gasket type in question, provided
that rotation has not been associated with leakage.
(b) The maximum p ermiss ib le b olt stress , Sb m a x ,
should be selected by the user. This value is intended
to eliminate damage to the bolt or assembly equipment
during assembly and may vary from site to site. It is typically in the range of 40% to 70% of ambient bolt yield
stress (see section 10) , and the bolt load is sufficiently
high to prevent self-loosening.
(c) The minimum permissible bolt stress, Sbmin, should
be selected by the user. This value is intended to provide a
lower limit such that bolting inaccuracies do not become a
significant portion of the specified assembly bolt stress,
Sbsel, and the bolt load is sufficiently high to prevent selfloosening. The value is typically in the range of 140 MPa to
245 MPa (20 ksi to 35 ksi).
(d) The maximum permissible bolt stress for the flange,
Sfmax, should be determined, based on the particular flange
configuration. This may be found using either elastic
closed-form solutions or elastic–plastic finite element
analysis, as outlined in section O-5. In addition, when
the limits are being calculated, the flange rotation at
that load, θfmax , should also be determined. Example
flange limit loads for elastic closed-form solutions and
elastic–plastic finite element solutions are outlined in
Tables O-4.1-1M through O-4.1-7. 2
O-4.2 Determining the Appropriate Bolt Stress
Once the limits are defined, the following process may
be used for each joint configuration. This process may be
performed using a spreadsheet or software program,
which allows the determination of many values simultaneously.
Step 1. Determine the target bolt stress in accordance
with eq. (O-1).
Step 2. Determine if the bolt upper limit controls
2
Limits are not presented for flanges less than NPS 2 (DN 50), as the
consequence of gross plastic deformation of such small flanges is generally inconsequential to joint integrity. The smaller joint dimensions mean
that the residual flange rotation must be significantly more severe when
compared to a larger flange before it can be detected, let alone affect joint
integrity. The joint component method may be applied to flange sizes or
classes not listed in this Appendix or to small bore flanges using the
method outlined in WRC Bulletin 538, but for small bore flanges the
bolt load should not be excessively limited due to flange strength
(i.e., minimum gasket stress levels should control the calculation,
over flange strength).
Sbsel
Step 3.
Sb max
)
(O-4)
Determine if the bolt lower limit controls
Sbsel
68
= min. ( Sbsel ,
= max. ( Sbsel ,
Sbmin
)
(O-5)
ð 22 Þ
ASME PCC-1–2022
Step 4.
= min. ( Sbsel , Sfmax )
Sbsel
Step 5.
achieved.
Step 6.
Sbsel
Step 7.
(O-7)
Sgmin- S [ A g /( Ab nb ) ]
Check if the gasket operating stress is main-
Ä
ÅÅ
ÅÅ Sg
ÅÅ
ÅÇ min-O
Ag
+(
ÉÑ
/ 4 PmaxG I.D . ÑÑ /
ÑÑÖ
)
2ÑÑ
(
g A b nb
)
(O-8)
Check if the gasket maximum stress is achieved.
Sbsel
Step 8.
(O-6)
Check if the gasket assembly seating stress is
Sbsel
tained. 4
Ab
A b·n b
Ag
GI.D.
nb
Pmax
ϕb
ϕg
Determine if the flange limit controls 3
Sgmax [ A g /( Ab nb ) ]
(O-9)
Check if the flange rotation limit is exceeded.
Sbsel
Sfmax ( gmax / fmax )
(O-10)
If one of the final checks (Step 5 through Step 8) is
exceeded, then j udgment should be used to determine
which controlling limit is more critical to the integrity
and, therefore, what the selected bolt load ought to be.
A table of assembly bolt torque values can then be calculated using eq. (O-2M) or eq. (O-2). An example table of
assembly bolt stresses and torque values using this
approach is outlined in Tables O-4.2-1 and O-4.2-2, respectively.
ð 22 Þ
=
=
=
=
=
=
=
=
0.3019 in. 2
2.42 in. 2
5.17 in. 2
4.00 in.
8
750 psig (0.75 ksi)
0.75 in.
0.7
Determine Bolt Stress
Step 1. Equation (O-1)
Step 2. Equation (O-4)
Step 3. Equation (O-5)
Step 4. Table O-4.1-2
Step 5. Equation (O-6)
Sb sel = 30(5.17/2.42) = 64 ksi
Sb sel = min. (64, 75) = 64 ksi
Sb sel = max. (64, 35) = 64 ksi
Sfmax = 63 ksi (note: Syo = Sya )
Sbsel = min. (64, 63) = 63 ksi
Additional Checks
Step 6. Equation (O-7)
Step 7. Equation (O-8)
Sb sel ≥
Sb sel ≥
12.5 (5.17/2.42) ≥ 26.7 ksi
Sbsel ≤
40 (5.17/2.42) ≤ 85 ksi
Step 8.
Equation (O-9)
Table O-4.1-4
Equation (O-10)
Equation (O-2)
Alternative: Use
Table O-3.2-1
✓
[6.0 × 5.17 + (π/4) × 0.75 ×
4.00 2 ] /(0.7 × 2.42) ≥ 24 ksi ✓
θfmax = 0.32 deg
✓
Sbsel ≤ 63 (1.0/0.32) ≤ 197 ksi ✓
Tb = 63,000 × 0.2 × 0.3019 × 0.75/12
Tb ≈ 240 ft-lb
Tb = 63 ksi × 3.78 ft lb/ksi = 238 ft-lb
Note that for some flanges (e.g., NPS 8, class 150) the
additional limits [eq. (O-7) through eq. (O-10) ] are not
satisfied. In those cases, engineering j udgment should
be used to determine which limits are more critical to
the joint integrity, and the value of Sb sel should be modified
accordingly. It should be noted that the values presented
are not hard limits (i.e., flange leakage will not occur if the
gasket stress falls 0.1 psi below the limit) and therefore
some leeway in using the values is to be considered
normal.
O-4.3 Example Calculation
NPS 3 Class 300 Carbon Steel RFWN Flange Operating at
Ambient Temperature (Identical Limits Used as Those in
Table O-4-2 .1 ) with a spiral-wound gasket per ASME
B16.20 and nut factor per Table O-4.2-2
3
In some cases (e.g., high-temperature stainless steel flanges), the yield
strength of the flange may reduce significantly during operation. While
this is important to consider, in some cases consideration of this effect
will result in the selection of an assembly bolt load that will result in joint
leakage. Once in operation, the bolt load becomes a secondary load (i.e.,
the load decreases with component yield) . Therefore, the effect of
temperature-driven component yield will be seen only as additional
j oint relaxation and minor permanent deformation. Often, the actual
material yield for stainless steel is significantly above the specified
minimum yield, and therefo re it is co nsidered mo re p rudent to
tighten to a higher load initially and risk possible permanent deformation
than to tighten to a lower load and risk certain joint leakage. However, if
the selected load minus bolt relaxation remains well above the flange
strength at operating temperature, permanent deformation can eventually cause issues (such as not being able to insert the bolts due to
residual flange rotation). In that case, it may be appropriate to use a
higher level of analysis than that presented in this Appendix.
4
Note that this simple treatment does not take into account the
changes in bolt load during operation due to component elastic interaction. A more complex relationship for the operational gasket stress
may b e used in lieu of this equation that includes the effects of
elastic interaction in changing the bolt stress. Note also that the use
of the G term from ASME BPVC, Section VIII, Division 1, Mandatory
Appendix 2 in place of GI.D. in this equation is considered acceptable.
O-5 DETERMINING FLANGE LIMITS
O-5.1 Elastic Analysis
A series of elastic analysis limits have been determined
that allow the calculation of the approximate assembly
bolt stress that will cause significant permanent deformation of the flange. Since this bolt stress is approximate, and
the flange specified minimum yield tends to be lower
bound (i.e., the actual material yield will exceed the specified minimum yield strength), it is considered appropriate
to use these limits without modification or additional
safety factor. An explanation of the limits and equations
used to determine the bolt stress can be found in WRC
Bulletin 538. The inaccuracy of applied bolt stress may
b e co ns idered in this p ro ces s ; ho wever, cautio n is
urged that including such considerations may lead to
69
ð 22 Þ
ASME PCC-1–2022
the selection of bolt stress levels that risk leakage. For
simplicity and to err on the side of a higher bolt load,
scatter is not considered essential to include in this
method.
analysis (FEA) . An explanation of the requirements for
performing such an analysis is outlined in WRC Bulletin
538. It is not necessary to rerun the analysis for minor
changes to the j oint configuration (such as different
gasket dimensions or minor changes to the flange material
yield strength) as linear interpolation using the ratio ofthe
change in gasket moment arm or ratio ofthe different yield
strength can be used to estimate the assembly bolt stress
limit for the new case.
O-5.2 Finite Element Analysis
A more accurate approach to determining the appropriate limit on assembly bolt load is to analyze the
j o int us ing elas tic–p las tic no nlinear finite element
70
ASME PCC-1–2022
Table O-3.2-1M
Reference Values (Target Torque Index) for Calculating Target Torque Values for Low-Alloy Steel Bolting
Based on Unit Prestress of 1 MPa (Root Area) (Metric Series Threads)
Basic Thread
Designation
Target Torque Index,
Ti, N·m/MPa (ft-lb/ksi), at Nut Factor, K, of
0.15
0.18
0.2
M12 × 1.75
0.13 (0.66)
0.16 (0.80)
0.17 (0.88)
M14 × 2
0.21 (1.07)
0.25 (1.28)
0.28 (1.42)
M16 × 2
0.33 (1.69)
0.40 (2.03)
0.44 (2.25)
M20 × 2.5
0.65 (3.31)
0.78 (3.97)
0.87 (4.42)
M22 × 2.5
0.90 (4.57)
1.08 (5.49)
1.20 (6.10)
M24 × 3
1.13 (5.73)
1.35 (6.87)
1.50 (7.63)
M27 × 3
1.68 (8.52)
2.01 (10.2)
2.23 (11.4)
M30 × 3.5
2.26 (11.5)
2.72 (13.8)
3.02 (15.3)
M33 × 3.5
3.11 (15.8)
3.74 (19.0)
4.15 (21.1)
M36 × 4
3.99 (20.3)
4.78 (24.3)
5.31 (27.0)
M39 × 4
5.20 (26.5)
6.24 (31.8)
6.94 (35.3)
M42 × 4.5
6.41 (32.6)
7.70 (39.1)
8.55 (43.5)
M45 × 4.5
8.07 (41.0)
9.68 (49.2)
10.8 (54.7)
M48 × 5
9.67 (49.2)
11.6 (59.0)
12.9 (65.6)
M52 × 5
12.6 (64.1)
15.1 (76.9)
16.8 (85.4)
M56 × 5.5
15.6 (79.6)
18.8 (95.5)
20.9 (106)
M64 × 6
23.7 (120)
28.4 (145)
31.6 (161)
M72 × 6
34.8 (177)
41.8 (212)
46.4 (236)
M80 × 6
48.9 (249)
58.7 (299)
65.2 (332)
M90 × 6
71.4 (363)
85.7 (436)
95.2 (484)
M100 × 6
99.8 (507)
120 (609)
133 (677)
GENERAL NOTES:
(a) The root areas are based on coarse-thread series for sizes M68 and smaller, and 6-mm pitch thread series for sizes M70 and larger. The
determination of root area for metric threads is based on a 6g tolerance.
(b) There are many ways of calculating target torque values for bolted pressure joints. The basis for Target Torque Index values in this table are
described below. When conditions vary from those considered in this table, such as different bolt materials or different coatings, refer to
Nonmandatory Appendix K to compute appropriate torque values.
(1) The tabulated target torque values are based on working surfaces that comply with sections 4 and 8.
(2) The Target Torque Index, Ti, is determined from eq. (O-2), for the nut factor indicated and applying a unit bolt load of 1 MPa for Sb sel. For
example, for an M20 bolt using a nut factor of 0.2
Ti = Sbsel K Ab b /1 000 = 1 × 0.2 × 21 7 × 20/1 000 = 0.87
(3) When the Target Torque Index, Ti, is determined, this value is multiplied by the selected assembly bolt load Sb sel to arrive at the final torque
value, Tb . For example, the M20 bolt in (2) is in the NPS 3 Class 300 flange described in the example calculation in para. O-4.3, for which the selected
assembly bolt stress, Sb sel , is 434 MPa. The target torque becomes
Tb = Sbsel × Ti = 434 MPa × 0.87 N m/MPa = 378 N m
This calculated value is rounded up to the nearest 5 N·m to become 380 N·m.
71
ð 22 Þ
ASME PCC-1–2022
ð 22 Þ
Table O-3.2-1
Reference Values (Target Torque Index) for Calculating Target Torque Values for Low-Alloy Steel Bolting
Based on Unit Prestress of 1 ksi (Root Area) (Inch Series Threads)
Nominal Bolt Size,
in.
Target Torque Index,
Ti, ft-lb/ksi (N·m/MPa), at Nut Factor, K, of
0.15
0.18
0.2
1
∕2
0.79 (0.15)
0.94 (0.19)
1.05 (0.21)
5
∕8
1.58 (0.31)
1.89 (0.37)
2.10 (0.41)
3
∕4
2.83 (0.56)
3.40 (0.67)
3.78 (0.74)
7
∕8
4.58 (0.90)
5.50 (1.08)
6.11 (1.20)
1
6.89 (1.35)
8.27 (1.63)
9.18 (1.81)
1 1 ∕8
10.2 (2.01)
12.3 (2.42)
13.7 (2.68)
1 1 ∕4
14.5 (2.85)
17.4 (3.43)
19.4 (3.81)
1 3 ∕8
19.9 (3.90)
23.8 (4.68)
26.5 (5.20)
1
1 ∕2
26.3 (5.18)
31.6 (6.22)
35.1 (6.91)
1 5 ∕8
34.1 (6.71)
41.0 (8.05)
45.5 (8.95)
1 3 ∕4
43.3 (8.52)
52.0 (10.2)
57.8 (11.4)
1 7 ∕8
53.9 (10.6)
64.7 (12.7)
71.9 (14.1)
2
66.3 (13.0)
79.5 (15.6)
88.3 (17.4)
2 1 ∕4
96.2 (18.9)
115 (22.7)
128 (25.2)
2 1 ∕2
134 (26.4)
161 (31.6)
179 (35.2)
2 3 ∕4
181 (35.6)
217 (42.7)
241 (47.4)
3
237 (46.6)
284 (55.9)
316 (62.1)
3 1 ∕4
304 (59.8)
365 (71.8)
406 (79.8)
3 1 ∕2
383 (75.3)
459 (90.3)
510 (100)
3 3 ∕4
474 (93.2)
569 (112)
632 (124)
4
579 (114)
694 (137)
771 (152)
GENERAL NOTES:
(a) The root areas are based on coarse-thread series for sizes 1 in. and smaller, and 8-pitch thread series for sizes 1 1 ∕8 in. and larger. The
determination of root area for inch series threads is based on a 2A tolerance.
(b) There are many ways of calculating target torque values for bolted pressure joints. The basis for Target Torque Index values in this table are
described below. When conditions vary from those considered in this table, such as different bolt materials or different coatings, refer to
Nonmandatory Appendix K to compute appropriate torque values.
(1) The tabulated target torque values are based on working surfaces that comply with sections 4 and 8.
(2) The Target Torque Index, Ti, is determined from eq. (O-2), for the nut factor indicated and applying a unit bolt load of 1 ksi for Sb sel. For
example, for a 3 ∕4 in. bolt using a nut factor of 0.2
Ti = Sbsel K Ab b /1 2 = 1 ,000 × 0.2 × 0.302 × 0.75 /1 2 = 3.78
where the value of 1,000 represents 1,000 psi rather than 1 ksi to maintain consistency in units.
(3) When the Target Torque Index, Ti, is determined, this value is multiplied by the selected assembly bolt load Sbsel to arrive at the final torque
value, Tb . For example, the 3 ∕4 in. bolt in (2) is in the NPS 3 Class 300 flange described in the example calculation in para. O-4.3, for which the selected
assembly bolt stress, Sb sel , is 63 ksi. The target torque becomes
Tb = Sbsel × Ti = 63 ksi × 3.78 ft-lb/ksi = 238 ft-lb
This calculated value is rounded up to the nearest 5 ft-lb to become 240 ft-lb.
72
ASME PCC-1–2022
Table O-4.1-1M
Pipe Wall Thickness Used for Following Tables (mm)
Table O-4.1-1
Pipe Wall Thickness Used for Following Tables (in.)
Class
NPS
150
300
600
900
Class
1500
2500
NPS
150
300
600
900
1500
2500
0.344
2
1.65
1.65
3.91
2.77
5.54
8.74
2
0.065
0.065
0.154
0.109
0.218
2 1 ∕2
2.11
2.11
3.05
5.16
7.01
14.02
2 1 ∕2
0.083
0.083
0.120
0.203
0.276
0.552
3
2.11
2.11
3.05
5.49
7.62
15.24
3
0.083
0.083
0.120
0.216
0.300
0.600
4
2.11
2.11
6.02
6.02
11.13
17.12
4
0.083
0.083
0.237
0.237
0.438
0.674
5
2.77
2.77
6.55
9.52
12.70
19.05
5
0.109
0.109
0.258
0.375
0.500
0.750
6
2.77
2.77
7.11
10.97
14.27
23.12
6
0.109
0.109
0.280
0.432
0.562
0.910
8
2.77
3.76
8.18
12.70
20.62
30.10
8
0.109
0.148
0.322
0.500
0.812
1.185
10
3.40
7.80
12.70
15.09
25.40
37.49
10
0.134
0.307
0.500
0.594
1.000
1.476
12
3.96
8.38
12.70
17.48
28.58
44.47
12
0.156
0.330
0.500
0.688
1.125
1.751
14
3.96
6.35
12.70
19.05
31.75
…
14
0.156
0.250
0.500
0.750
1.250
…
16
4.19
7.92
14.27
23.83
34.93
…
16
0.165
0.312
0.562
0.938
1.375
…
18
4.78
9.53
20.62
26.19
44.45
…
18
0.188
0.375
0.812
1.031
1.750
…
20
4.78
9.53
20.62
32.54
44.45
…
20
0.188
0.375
0.812
1.281
1.750
…
24
5.54
14.27
24.61
38.89
52.37
…
24
0.218
0.562
0.969
1.531
2.062
…
26
7.92
12.70
23.73
35.09
…
…
26
0.312
0.500
0.934
1.382
…
…
28
7.92
12.70
25.56
37.79
…
…
28
0.312
0.500
1.006
1.488
…
…
30
6.35
15.88
27.38
40.49
…
…
30
0.250
0.625
1.078
1.594
…
…
32
7.92
15.88
29.21
43.19
…
…
32
0.312
0.625
1.150
1.700
…
…
34
7.92
15.88
31.03
45.89
…
…
34
0.312
0.625
1.222
1.807
…
…
36
7.92
19.05
32.86
48.59
…
…
36
0.312
0.750
1.294
1.913
…
…
38
9.53
17.60
34.69
51.29
…
…
38
0.375
0.693
1.366
2.019
…
…
40
9.53
18.52
36.51
53.99
…
…
40
0.375
0.729
1.437
2.126
…
…
42
9.53
19.45
38.34
56.69
…
…
42
0.375
0.766
1.509
2.232
…
…
44
9.53
20.37
40.16
59.39
…
…
44
0.375
0.802
1.581
2.338
…
…
46
9.53
21.30
41.99
62.09
…
…
46
0.375
0.839
1.653
2.444
…
…
48
9.53
22.23
43.81
64.79
…
…
48
0.375
0.875
1.725
2.551
…
…
73
ASME PCC-1–2022
Table O-4.1-2M
Bolt Stress Limit for SA-105 Steel Flanges
Using Elastic– Plastic FEA (MPa)
Table O-4.1-2
Bolt Stress Limit for SA-105 Steel Flanges
Using Elastic– Plastic FEA (ksi)
ASME B16.5 and ASME B16.47 Series A — Weld Neck
ASME B16.5 and ASME B16.47 Series A — Weld Neck
Class
Class
NPS
150
300
600
900
1500
2500
NPS
2
579
398
579
434
471
471
2
150
300
600
900
1500
84
58
84
63
68
2 1 ∕2
688
326
434
398
471
543
3
724
434
615
579
471
4
543
615
688
434
507
5
543
724
652
507
543
6
724
579
579
579
2500
68
2 1 ∕2
100
47
63
58
68
79
579
3
105
63
89
84
68
84
507
4
79
89
100
63
74
74
543
5
79
105
95
74
79
79
615
579
6
105
84
84
84
89
84
8
724
579
615
507
579
579
8
105
84
89
74
84
84
10
579
543
543
507
615
579
10
84
79
79
74
89
84
12
724
543
507
543
579
615
12
105
79
74
79
84
89
14
579
434
471
543
543
…
14
84
63
68
79
79
…
16
543
434
471
579
507
…
16
79
63
68
84
74
…
18
724
471
579
543
543
…
18
105
68
84
79
79
…
20
615
507
507
579
507
…
20
89
74
74
84
74
…
24
615
471
507
543
507
…
24
89
68
74
79
74
…
26
253
253
362
434
…
…
26
37
37
53
63
…
…
…
28
217
253
326
398
…
…
28
32
37
47
58
…
30
253
290
434
434
…
…
30
37
42
63
63
…
…
32
217
253
398
434
…
…
32
32
37
58
63
…
…
34
190
290
434
398
…
…
34
28
42
63
58
…
…
36
217
253
398
434
…
…
36
32
37
58
63
…
…
38
253
579
579
543
…
…
38
37
84
84
79
…
…
40
217
543
615
543
…
…
40
32
79
89
79
…
…
42
253
543
615
579
…
…
42
37
79
89
84
…
…
44
226
579
615
543
…
…
44
33
84
89
79
…
…
46
253
615
652
543
…
…
46
37
89
95
79
…
…
48
253
507
579
579
…
…
48
37
74
84
84
…
…
74
ASME PCC-1–2022
Table O-4.1-3
Flange Rotation for SA-105 Steel Flanges Loaded to
Table O-4.1-2M/Table O-4.1-2 Bolt Stress
Using Elastic– Plastic FEA (deg)
ASME B16.5 and ASME B16.47 Series A — Weld Neck
Class
NPS
150
300
600
900
1500
2500
2
0.37
0.34
0.23
0.21
0.20
0.16
2 1 ∕2
0.36
0.31
0.24
0.20
0.21
0.17
3
0.23
0.32
0.26
0.26
0.22
0.16
4
0.50
0.37
0.29
0.26
0.21
0.17
5
0.56
0.33
0.29
0.28
0.20
0.17
6
0.61
0.41
0.30
0.27
0.21
0.16
8
0.46
0.45
0.31
0.28
0.21
0.17
10
0.70
0.43
0.34
0.30
0.21
0.17
12
0.74
0.48
0.35
0.34
0.22
0.16
14
0.68
0.48
0.39
0.33
0.24
…
16
0.83
0.48
0.39
0.34
0.23
…
18
0.88
0.51
0.41
0.33
0.24
…
20
0.87
0.58
0.40
0.32
0.24
…
24
0.95
0.59
0.41
0.31
0.26
…
26
0.87
0.59
0.43
0.35
…
…
28
0.84
0.50
0.40
0.37
…
…
30
0.97
0.60
0.43
0.35
…
…
32
0.98
0.49
0.48
0.37
…
…
34
0.87
0.52
0.41
0.35
…
…
36
0.85
0.51
0.44
0.38
…
…
…
38
1.09
0.51
0.39
0.34
…
40
0.93
0.52
0.43
0.37
…
…
42
1.04
0.60
0.43
0.35
…
…
44
0.91
0.54
0.43
0.35
…
…
46
1.00
0.52
0.43
0.37
…
…
48
1.04
0.63
0.42
0.35
…
…
75
ASME PCC-1–2022
Table O-4.1-4M
Bolt Stress Limit for SA-105 Steel Flanges
Using Elastic Closed Form Analysis (MPa)
Table O-4.1-4
Bolt Stress Limit for SA-105 Steel Flanges
Using Elastic Closed Form Analysis (ksi)
ASME B16.5 and ASME B16.47 Series A — Weld Neck
ASME B16.5 and ASME B16.47 Series A — Weld Neck
Class
Class
NPS
150
300
600
900
1500
2500
NPS
2
450
310
515
332
413
447
2
1
150
300
65
600
45
900
1500
2500
48
60
65
75
1
2 ∕2
576
284
388
377
441
496
2 ∕2
83
41
56
55
64
72
3
724
394
545
517
432
531
3
105
57
79
75
63
77
4
445
561
633
417
492
454
4
65
81
92
61
71
66
5
402
724
663
468
528
501
5
58
105
96
68
77
73
6
541
593
630
543
605
535
6
78
86
91
79
88
78
8
724
614
657
463
576
557
8
105
89
95
67
83
81
10
503
639
566
444
627
543
10
73
93
82
64
91
79
12
712
607
563
494
554
594
12
103
88
82
72
80
86
14
583
454
513
526
485
…
14
84
66
74
76
70
…
16
563
398
508
532
487
…
16
82
58
74
77
71
…
18
614
472
594
534
521
…
18
89
69
86
77
76
…
20
568
451
482
545
501
…
20
82
65
70
79
73
…
24
479
365
450
546
481
…
24
69
53
65
79
70
…
26
218
242
359
448
…
…
26
32
35
52
65
…
…
28
193
264
354
399
…
…
28
28
38
51
58
…
…
30
228
290
447
465
…
…
30
33
42
65
67
…
…
32
173
272
396
460
…
…
32
25
40
58
67
…
…
34
160
296
463
418
…
…
34
23
43
67
61
…
…
36
207
261
404
436
…
…
36
30
38
59
63
…
…
…
38
211
557
623
551
…
…
38
31
81
90
80
…
40
199
536
634
532
…
…
40
29
78
92
77
…
…
42
218
581
626
585
…
…
42
32
84
91
85
…
…
44
221
676
638
570
…
…
44
32
98
93
83
…
…
46
238
724
687
563
…
…
46
35
105
100
82
…
…
48
222
524
605
625
…
…
48
32
76
88
91
…
…
ASME B16.5 — Slip-On
ASME B16.5 — Slip-On
Class
Class
NPS
150
300
600
900
1500
NPS
150
300
600
900
1500
2
724
360
572
423
413
2
105
52
83
61
60
1
1
2 ∕2
534
321
410
377
441
2 ∕2
77
47
60
55
64
3
714
446
563
518
…
3
103
65
82
75
…
4
394
594
601
467
…
4
57
86
87
68
…
5
446
678
507
492
…
5
65
98
74
71
…
6
603
458
495
536
…
6
87
66
72
78
…
8
724
538
515
456
…
8
105
78
75
66
…
10
477
472
430
429
…
10
69
68
62
62
…
12
674
476
421
468
…
12
98
69
61
68
…
14
445
283
344
504
…
14
65
41
50
73
…
16
453
320
370
509
…
16
66
46
54
74
…
18
561
376
546
514
…
18
81
55
79
75
…
20
487
428
499
524
…
20
71
62
72
76
…
24
535
395
500
528
…
24
78
57
73
77
…
76
ASME PCC-1–2022
Table O-4.1-5
Flange Rotation for SA-105 Steel Flanges Loaded to
Table O-4.1-4M/Table O-4.1-4 Bolt Stress
Using Elastic Closed Form Analysis (deg)
Table O-4.1-5
Flange Rotation for SA-105 Steel Flanges Loaded to
Table O-4.1-4M/Table O-4.1-4 Bolt Stress
Using Elastic Closed Form Analysis (deg) (Cont’ d)
ASME B16.5 and ASME B16.47 Series A — Weld Neck
ASME B16.5 — Slip-On
Class
Class
NPS
150
300
600
900
1500
2500
NPS
150
300
600
900
1500
2
0.20
0.20
0.15
0.13
0.09
0.08
2
0.34
0.28
0.21
0.14
0.10
2 1 ∕2
0.22
0.19
0.17
0.11
0.09
0.07
2 1 ∕2
0.35
0.29
0.24
0.12
0.10
3
0.20
0.22
0.19
0.15
0.12
0.08
3
0.40
0.32
0.27
0.21
…
4
0.28
0.27
0.19
0.17
0.14
0.10
4
0.52
0.38
0.27
0.21
…
5
0.29
0.26
0.20
0.18
0.14
0.10
5
0.64
0.43
0.30
0.20
…
6
0.33
0.32
0.24
0.16
0.15
0.10
6
0.73
0.49
0.33
0.20
…
8
0.35
0.36
0.28
0.18
0.15
0.11
8
0.84
0.57
0.38
0.22
…
10
0.44
0.40
0.27
0.17
0.16
0.10
10
1.02
0.59
0.40
0.27
…
12
0.46
0.42
0.32
0.21
0.15
0.11
12
1.09
0.66
0.47
0.33
…
14
0.46
0.38
0.35
0.24
0.15
…
14
1.14
0.70
0.50
0.33
…
16
0.54
0.36
0.36
0.23
0.17
…
16
1.26
0.76
0.52
0.33
…
18
0.54
0.41
0.34
0.26
0.18
…
18
1.34
0.80
0.52
0.34
…
20
0.60
0.39
0.33
0.24
0.19
…
20
1.38
0.86
0.55
0.33
…
24
0.59
0.37
0.34
0.26
0.20
…
24
1.52
0.91
0.58
0.33
…
26
0.77
0.55
0.42
0.33
…
…
28
0.79
0.56
0.43
0.33
…
…
30
0.88
0.58
0.42
0.34
…
…
32
0.84
0.58
0.43
0.34
…
…
34
0.85
0.57
0.43
0.34
…
…
36
0.90
0.56
0.43
0.34
…
…
38
0.93
0.71
0.48
0.35
…
…
40
0.93
0.71
0.48
0.35
…
…
42
0.94
0.71
0.48
0.36
…
…
44
0.96
0.71
0.48
0.36
…
…
46
0.98
0.71
0.48
0.36
…
…
48
0.95
0.71
0.48
0.36
…
…
77
ASME PCC-1–2022
Table O-4.1-6M
Bolt Stress Limit for SA-182 F304 Steel Flanges
Using Elastic– Plastic FEA (MPa)
Table O-4.1-6
Bolt Stress Limit for SA-182 F304 Steel Flanges
Using Elastic– Plastic FEA (ksi)
ASME B16.5 and ASME B16.47 Series A — Weld Neck
ASME B16.5 and ASME B16.47 Series A — Weld Neck
Class
Class
NPS
150
300
600
900
1500
2500
NPS
300
600
900
1500
2
434
326
471
362
362
398
2
150
63
47
68
53
53
2500
58
2 1 ∕2
543
253
362
326
398
434
2 1 ∕2
79
37
53
47
58
63
3
724
362
507
471
362
471
3
105
53
74
68
53
68
4
362
471
543
362
434
434
4
53
68
79
53
63
63
5
398
615
543
398
434
434
5
58
89
79
58
63
63
6
543
471
471
471
471
471
6
79
68
68
68
68
68
8
579
471
507
434
471
471
8
84
68
74
63
68
68
10
434
434
434
434
507
471
10
63
63
63
63
74
68
12
471
434
434
434
471
507
12
68
63
63
63
68
74
14
434
326
362
434
434
…
14
63
47
53
63
63
…
16
362
362
362
471
434
…
16
53
53
53
68
63
…
18
398
398
471
471
434
…
18
58
58
68
68
63
…
20
362
398
398
471
434
…
20
53
58
58
68
63
…
24
362
362
398
434
398
…
24
53
53
58
63
58
…
26
217
181
290
362
…
…
26
32
26
42
53
…
…
28
181
217
290
326
…
…
28
26
32
42
47
…
…
30
217
217
362
362
…
…
30
32
32
53
53
…
…
32
181
217
326
362
…
…
32
26
32
47
53
…
…
34
172
253
362
326
…
…
34
25
37
53
47
…
…
36
181
217
326
362
…
…
36
26
32
47
53
…
…
38
181
471
471
434
…
…
38
26
68
68
63
…
…
40
145
434
507
434
…
…
40
21
63
74
63
…
…
42
217
434
507
471
…
…
42
32
63
74
68
…
…
44
154
471
471
434
…
…
44
22
68
68
63
…
…
46
217
507
507
434
…
…
46
32
74
74
63
…
…
48
217
398
471
471
…
…
48
32
58
68
68
…
…
78
ASME PCC-1–2022
Table O-4.1-7
Flange Rotation for SA-182 F304 Steel Flanges Loaded to
Table O-4.1-6M/Table O-4.1-6 Bolt Stress
Using Elastic– Plastic FEA (deg)
ASME B16.5 and ASME B16.47 Series A — Weld Neck
Class
NPS
150
300
600
900
1500
2500
2
0.47
0.34
0.21
0.17
0.15
0.16
2 1 ∕2
0.40
0.29
0.20
0.20
0.24
0.13
3
0.21
0.27
0.29
0.23
0.16
0.12
4
0.55
0.41
0.25
0.21
0.19
0.15
5
0.61
0.32
0.27
0.25
0.20
0.18
6
0.64
0.38
0.27
0.24
0.17
0.15
8
0.46
0.42
0.34
0.25
0.19
0.15
10
0.91
0.47
0.26
0.26
0.17
0.15
12
0.79
0.37
0.31
0.26
0.20
0.17
14
0.89
0.41
0.28
0.25
0.19
…
16
1.02
0.41
0.29
0.31
0.20
…
18
0.93
0.54
0.28
0.25
0.18
…
20
1.02
0.53
0.35
0.29
0.20
…
24
1.12
0.44
0.37
0.24
0.23
…
26
0.81
0.53
0.33
0.29
…
…
28
0.52
0.45
0.37
0.25
…
…
30
0.91
0.41
0.35
0.29
…
…
32
0.59
0.43
0.31
0.31
…
…
34
0.68
0.37
0.34
0.24
…
…
36
0.54
0.44
0.30
0.31
…
…
38
1.00
0.46
0.35
0.26
…
…
40
0.91
0.55
0.35
0.28
…
…
42
0.52
0.64
0.34
0.32
…
…
44
0.54
0.48
0.34
0.27
…
…
46
1.00
0.55
0.41
0.28
…
…
48
0.51
0.55
0.38
0.32
…
…
79
ASME PCC-1–2022
Table O-4.2-1
Example Bolt Stress for SA-105 Steel Weld-Neck Flanges, SA-193 B7 Steel Bolts,
and Spiral-Wound Gasket With Inner Ring (ksi)
ASME B16.5 and ASME B16.47 Series A — Weld Neck
Calculated Bolt Stress (ksi)
300
600
900
1 500
NPS 1 50
2
21 /2
3
4
5
6
8
10
12
14
16
18
20
24
26
28
30
32
34
36
38
40
42
44
46
48
75
75
75
75
75
75
75
75
75
75
75
75
75
75
37
35
37
35
35
35
37
35
37
35
37
37
56
44
63
75
75
75
75
75
75
63
63
68
74
68
37
37
42
37
42
37
75
68
71
68
69
63
56
44
64
75
75
74
75
62
66
54
58
62
57
50
41
38
41
35
36
35
39
36
35
35
35
35
43
40
60
49
48
56
44
40
49
44
42
45
38
35
35
35
35
35
35
35
35
35
35
35
35
35
2500
43
40
38
42
36
38
35
35
35
35
35
35
35
35
Legend:
= lim ited by min. bolt stress
= lim ited by max. bolt stress
= lim ited by max. gasket stress
= lim ited by max. flange stress
GENERAL NOTE: Example limits used in the analysis:
Sb min = 35 ksi
Sb max = 75 ksi
Sfmax = from Table O-4.1-2
Sg t = 30 ksi
Sg max = 40 ksi
Sg min-S = 12.5 ksi
Sgmin-O = 6 ksi
θg max = 1.0 deg
80
35
35
35
35
35
35
35
35
35
ASME PCC-1–2022
Table O-4.2-2
Example Assembly Bolt Torque for SA-105
Steel Weld-Neck Flanges, SA-193 B7 Steel Bolts,
and Spiral-Wound Gasket With Inner Ring (ft-lb)
ASME B16.5 and ASME B16.47 Series A — Weld Neck
Class
NPS
150
300
600
900
1500
2500
2
160
120
120
265
265
325
2 1 ∕2
160
170
170
370
370
480
3
160
240
245
370
520
680
4
160
285
460
665
810
1,230
5
285
285
690
935
1,275
2,025
6
285
285
680
765
1,015
3,095
8
285
460
1,025
1,175
1,615
3,095
10
460
690
1,210
1,070
2,520
6,260
12
460
1,025
1,270
1,290
3,095
8,435
14
690
860
1,430
1,540
4,495
…
16
690
1,220
2,035
1,915
6,260
…
18
1,025
1,325
2,825
3,210
8,435
…
20
1,025
1,425
2,590
3,380
11,070
…
24
1,455
2,400
3,570
6,260
17,865
…
26
715
1,675
2,950
8,435
…
…
28
680
1,675
3,370
11,070
…
…
30
715
2,425
3,620
11,070
…
…
32
1,230
2,645
4,495
14,195
…
…
34
1,230
3,025
4,610
17,865
…
…
36
1,230
3,250
6,260
17,865
…
…
38
1,295
2,635
5,050
17,865
…
…
40
1,230
3,085
4,670
17,865
…
…
42
1,295
3,230
6,260
17,865
…
…
44
1,230
3,910
6,260
22,120
…
…
46
1,295
4,985
6,260
27,000
…
…
48
1,295
4,570
8,435
27,000
…
…
GENERAL NOTES:
(a) Nut factor used: K = 0.2.
(b) Torque rounded up to nearest 5 ft-lb.
81
ASME PCC-1–2022
NONMANDATORY APPENDIX P
TROUBLESHOOTING FLANGE JOINT LEAKAGE
ð 22 Þ
P-1 INTRODUCTION
(4) fluid hammer effects
(5) recent changes of any kind (process, flow rate,
service fluid, or other)
(6) actual equipment, flange, and bolt temperatures
as measured with the best available means, such as contact
thermometer, infrared device, or indicating crayon
The performance of a pressurized, gasketed, bolted
flange joint, either standard or Code designed, is measured
in terms of its ability to remain leak-free through all anticipated plant operations. When a leak occurs, whether
minor or major, the cause should be determined.
CAUTION: It is common for process operating gauges to be
inaccurate; avoid using them if possible.
P-2 SCOPE
(7) removal of insulation from or application of insulation to joint or bolts while the flange joint assembly is
operating
(8) human factors: intervention (op en or close
valve) , time of day or shift, training (unit operation
and technical), etc.
(c) Attempts to Correct the Leak
(1 ) tightening attempts (turn-of-nut, single-stud replacement, etc.)
(-a) number of, method for, and result for each
attempt
(-b) timing of the attempts: while the flange joint
was online or temporarily isolated?
(2) gasket replacement attempts: type of replacement, i.e., in-kind or different gasket? Result?
(3) sealant injection attempts: number of, method
for, and result for each attempt
(d) Previous Assembly Practices
(1 ) assembler qualifications and training
(2) as s e mb l y p ro ce dure s and /o r AS M E P C C - 1
conformance
(3) assembly tooling used, e.g., poor tool access, ineffective staging, nut socket fit, calibration
(4) ability to access the joint to perform the assembly
(e) Specification s Con form an ce. D id the following
components meet the standard or specification they
were designed to?
(1 ) gasket
(2) hardware (bolts or studs, nuts, washers; were
washers through-hardened?)
(3) flanges
(4) lubricant
(5) support arrangements for external loads (weight,
dynamic, or thermal)
(6) piping thermal expansion restraint arrangement
(f) Physical Condition, Inspection, and Maintenance of
the Flange Joint Assembly (See Form P-3-1 )
(1 ) previous inspection and maintenance records.
This Appendix is intended to assist flange joint troubleshooting efforts by providing
(a) an investigative and diagnostic evaluation guide to
characterize the joint in terms of its historical, operating,
and mechanical status
(b) a sample Flange Joint Leak Report
(c) flange design and acceptable practice considerations
(d) a set of diagnostic troubleshooting tables
P-3 INVESTIGATIVE AND DIAGNOSTIC
EVALUATION GUIDE
Troubleshooting a flange joint leak may involve some or
all of the following criteria:
(a) Operating History of the Flange Joint Assembly
(1 ) time in service overall (age of joint)
(2) time in service since the previous issue
(3) timing ofthe leak, i.e., when in the operating cycle
the leak occurred: start-up, shutdown, upset, normal run
cycle, foul weather?
(4) nature of leak (single or multiple locations
around j oint; drip, vapor, flow intermittent, constant,
extreme, or catastrophic)
(5) nature o f p re vi o us di ffi cul ti e s , e val uati o n
summaries, and remedies such as system operation maintenance and equipment changes
(6) prior assembly records and procedure
(7) last-applied bolt load: the size ofthe load, method
and time of application, method of measurement
(b) Operating Conditions of the Flange Joint Assembly
(1 ) external environmental conditions: unremarkable, heavy rain, high wind, very cold temperature, etc.
(2) normal operating temperature, pressure, service
fluid, flow rate, and other loadings
(3) upset temperatures, pressures, flow rate, and
other loadings
82
ASME PCC-1–2022
Form P-3-1 Sample Flange Joint Leak Report
EQUIPMENT IDENTIFICATION
Unit no
.:
E q u i pm en t n o. :
D a te :
JOINT DESCRIPTION
J oi n t I . D. n o. :
I S O o r d ra wi n g n o . :
G a s ke t m a te ri a l :
Fl a n g e si ze:
G a s ket typ e :
F l a n g e p re s s u re cl a s s :
F l a n g e te m p era tu re :
B o l t tem p e r a tu re :
D e s cri b e th e u s e o f th e j o i n t ( e . g . , “ ch a n n e l co ve r” ) :
D e s cri b e b o l t l u b ri ca n t co n d i ti o n a t ti m e o f l e a k:
LEAK DESCRIPTION
Le a k typ e ( ch e ck a l l th a t a p p l y) :
Ti m i n g o f l e a k ( ch eck o n e ) :
wi s p
d ro p s
a t h yd ro - te s t
a fter
s tre a m s
em i ssi on s
a t l a te r s ta rt- u p s
a t fi rs t s ta rt- u p
a t c o o l d o wn
m o n th s o f o p e ra ti on
Circle the best descriptive location and orientation of the joint:
To p
Piping Joints
E a st
Ve rti ca l
To p
We s t
E a st
N o rth
S o u th
Wes t
E a st
N o rth
S o u th
H o ri zo n ta l
B o tto m
B o tto m
Wes t
Mark the leak location:
Measure the gap between the flanges:
Measure the flange offset at four locations:
1 2
1 2
9
3
9
1 2
3
9
6
6
6
Measure the torque it takes to move the nuts:
Record applied torque during tightening:
1 2
9
3
1 2
3
9
6
3
6
83
ASME PCC-1–2022
Form P-3-1 Sample Flange Joint Leak Report (Cont’d)
After torquing, mark the nuts:
0 = nuts do not turn
XX = nuts turn
X = nuts tu rn slightly
XXX = nuts turn very easily
Leakage status after abatement actions:
No change
Reduced
Comments:
Name (print):
Signature:
84
Stopped
ASME PCC-1–2022
P-4.1.1 External Bending or Axial Force
(2) physical changes such as to layout, pipe supports,
and environmental factors.
(3) physical disassembly observations: were there
loose or near-loose bolts? If so, how many? What was
the relationship of the loose bolts to the leak? What
was the condition of the gasket? Were there signs of
galling at the nut face or on the bolts?
(4) location of j oint: is it near the nozzle or other
fixed points? Does it have the proper support? Are the
thermal expansion restraints properly located?
(5) facing co nditio n: co rro s io n, warp ing, weld
spatter, leakage path, wire draw?
(6) leakage onto the j oint from another source,
creating corrosion or DTE (differential thermal expansion) problems?
(7) alterations to the flange: number and type (e.g.,
removal of nubbin, conversion of RTJ gasket to spiralwound on raised-face flange).
(8) thickness of the flange: is the flange within
minimum thickness requirements? (Check flange j oint
standard or relevant Code calculation.)
(9) flange alignment measurements, current and
previous.
(1 0) sup p ort (o r lack o f) for external lo adings
(weight or thermal).
(1 1 ) condition ofinsulation, ifany, ofbolts and flange
and removable insulation pads
(1 2) effective length for bolts: is it consistent for all
bolts?
(a) Review design documents and calculations for any
sp ecified additional forces and compare these with
current operating circumstances. Consider the reactions
of piping systems against nozzles and vessel joints.
(b) Review against design documents the actual piping
system layout, support, guides, and constraints for sources
of unanticipated bending or axial forces. Consider the
effect of unintended restraint of piping thermal expansion
in terms of forces and bending moments.
(c) Evaluate the effect of external loads on the joint.
Reference [1] provides a methodology for the evaluation
of external loadings on pressurized flange joints. Public
computer programs exist that are fully capable of evaluating external loadings on flange joints.
(d) Consider all loads on the flange joint as covered in
ASME BPVC, Section VIII, Division 1, Part UG, UG-22 to
diminish the likelihood of leakage.
P-4.1.2 Differential Thermal Expansion (DTE). The
differential thermal expansion between the bolts and
flanges is present in all joints operating at nonambient
temperatures. Consider both axial and radial effects on
flange components. Generally, when the coefficients of
expansion of flanges and bolting are closely matched,
p ro p e rl y as s e mb le d j o i nts wi th an o p e rati ng flui d
temperature less than 260°C (500°F) should withstand
normal start-ups and shutdowns.
P-4.1.3 Pressure Surge. If the flange joints are within a
system subject to pressure surges, review the restraints
and anchors to ensure they are capable of withstanding
both DTE and surge loads.
P-4 FLANGE DESIGN AND ACCEPTABLE PRACTICE
CONSIDERATIONS
The successful performance ofa bolted joint assembly is
contingent on many choices made prior to assembly. A
well-assembled joint cannot function as intended if the
des i gn, s p e cifi cati o n, o r fab ricatio n do es no t meet
agreed-upon standards. It is crucial to understand the
interactions, interdependencies, and interrelationships
that are inherent in a bolted j oint assembly and the
effect they have on the performance of the joint.
Paragraphs P-4.1 through P-4.6 provide design and
practice considerations to assist the troubleshooter in
spotting potential problems associated with a particular
j oint. The considerations apply to both standard and
n o n s ta n d a rd fl a n ge j o i n ts th a t h a ve e xp e ri e n c e d
chronic leakage.
P-4.2 Joint Flexibility
In general, joints assembled with strong, long bolts are
more flexible than those assembled with short bolts, and
two-flange j oints are more flexible than single-flange
joints. A more flexible joint will withstand more abuse,
such as DTE loads. Stronger bolts also permit higher
assembly loads if needed.
P-4.2.1 Single-Flange Joints. Flange joints consisting
of a single flange with bolts threaded into tapped holes are
inherently less flexible and generally more troublesome
than two-flange joints. The shorter effective stretching
length of the bolts in a single-flange j oint makes the
j oint less tolerant of gasket thickness loss, relaxation,
and DTE effects. A single-flange j oint is roughly twice
as s ti ff as a two - fl ange j o i nt o f the s ame s i z e and
rating and therefore will suffer roughly twice the bolt
load loss for each 0.02-mm (0.001-in.) loss of gasket thickness (post-assembly).
P-4.1 Loading Effects
Often a flange joint is designed (or selected) for internal
s ys tem p ressure lo adings only, whereas s ignificant
external forces, thermal loadings, and pressure surges
may occur and affect the gasket load and joint tightness.
85
ASME PCC-1–2022
P-4.2.2 Increasing Bolt Flexibility. Consider using
extension collars or longer bolts to increase effective
bo lt length, which will increase bolt flexibility [see
para. 9(a)(2) for methods and calculations)] .
(b) Experience has shown that the use of an inner ring
can p ro vide b enefits fo r sp iral- wo und gas kets . Fo r
guidance on inner-ring usage, see ASME B16.20.
(c) C onventional do uble-j acketed gasket designs,
regardless offiller material, have proven to be problematic
in joints subjected to differential radial movement of the
flanges, such as in tubesheet joints on shell-and-tube heat
exchangers. This is due to the destruction of the metal
j acket or increased gasket stress relaxation due to the
wear of the metal jacket. Both of these failure mechanisms
are caused by the differential radial movement (radial
shear) of the flange seating surfaces, thereby exacerbating
the inherent poor sealability characteristics of the gasket.
(d) Field application of graphite tape to conventional
double-jacketed gaskets is not recommended and is not as
effective as purchasing a gasket with graphite facings
specified as part of the inherent gasket design.
(e) Gaskets that incorporate flexible graphite facings
i n to th e d e s i gn , s uch as th e th re e - p l y co rru gate d
metal-style gasket with flexible graphite layer on each
face of the gasket, have been found to provide improved
elastic recovery characteristics and suitability for broad
service applications.
(f) The bolting should be able to provide the required
gasket seating stress for the selected gasket type per
Nonmandatory Appendix O.
(g) Gasket width may be adj usted to optimize the
seating stress for the available bolt load. The target
gasket stress will depend on the gasket properties and
is typically provided in the manufacturer’s data. Many
gasket types will also have a minimum or maximum recommended width, thickness, or both.
P-4.2.3 Flange Rigidity. For best joint performance,
the flange should meet the rigidity requirements of
ASME BPVC, Section VIII, Division 1, Mandatory Appendix
2, 2-14(a), unless successful experience indicates otherwise. Consider adding split backing rings to increase
ri gidi ty fo r e xi s ti ng flange s and to li mit e xce s s ive
flange rotation.
P-4.3 Bolting Material
(a) If yielding of low-strength bolts is evident (or
predictable by computation) , consider using high- or
intermediate-strength bolting to allow a greater target
bolt prestress. See ASME B1 6.5 , Table 1 B for a list of
high-, intermediate-, and low-strength bolting.
C AU TI O N : Changing fro m lo w- s trength b o lts to highstrength bolts can have a detrimental effect on flange
stress. Low- strength bolts are commonly used in light
gauge, composite, or low-ductility flanges. In these cases,
consideration of higher bolt loads and the assembly proced u re s u s e d i s p ru d e n t to a vo i d fl a n ge d a m a ge . S e e
Nonmandatory Appendix O for guidance.
(b) M atch coefficients of expansion of flange and
bolting as closely as possible (see para. P-4.1.2).
(c) If stainless steel bolting is required, consider using
SA-453 Grade 660 since it has strength properties that
allow a higher target bolt prestress than other stainless
steel bolts. Similarly, strain-hardened SA-193 B8 Cl. 2 bolts
are usually preferable to SA-193 B8 Cl. 1 bolts due to their
higher yield and ultimate tensile strength.
P-4.5.2 Gasket Location and Contact Surface
(a) Check that the gasket contact surface location is as
close as practicable to the bolt circle to reduce flange rotation effects at the seating surface. See Nonmandatory
Appendix O, section O-4.
(b) For most nonpiping applications, the gasket contact
surface finish should range from 3.2 μm to 6.3 μm (125 μin.
to 250 μin.). Follow ASME B16.5 for piping flange finishes.
(c) Repair radial scratches deeper than the surface
finish. See Nonmandatory Appendix D.
(d) The use of nubbins is not a generally accepted good
engineering practice regardless of gasket type. Remove
nubbins if the differential radial movement of flanges
occurs or is evidenced by inspection of facing surfaces.
P-4.4 Bolt Spacing
(a) Check minimum bolt spacing based on wrenchclearance considerations to confirm accessibility.
(b) Low gasket stress can result from excessive bolt
spacing. For bolt-spacing information and calculations,
see ASME BPVC, Section VI II , Division 1 , Mandatory
Appendix 2 . Where tightness-based gasket constants
are used, see refs. [2] and [3] for additional information.
P-4.5 Gaskets
P-4.5.1 Gasket Selection
(a) Gasket styles provided with a flexible graphite
fa c i n g l a ye r o n e a c h s i d e , s u c h a s s p i ra l - wo u n d ,
grooved-metal, and corrugated-metal gaskets, offer not
only vastly improved resistance to radial shear but
also enhanced sealability. Consider using these gaskets
as replacements for gasket styles not having a flexible
graphite facing layer.
P-4.6 Flange-Type Selection
P-4.6.1 Tapered-Hub-Type Flange. A tapered-hubtype flange (see Figure P-4.6.1-1)
(a ) p ro vi de s mo s t favo rab le trans i ti o n o f s tres s
through the tapered hub from the flange thickness to
the shell thickness, a consideration favorable for services
for which fatigue and brittle fracture avoidance are
governing design requirements
86
ASME PCC-1–2022
Figure P-4.6.1-1
Tapered-Hub-Type Flange
weld leakage and resultant hidden corrosion in the crevice
between the flange inside diameter and the shell.
(5) Avoid using slip-on-type flanges in hot hydrogen
service. For carbon steel, this is usually defined as a
hydro gen p artial p res sure exceeding 6 9 0 kPa (1 0 0
p sia) with a co rresp onding coincident temp erature
exceeding 200°C (400°F).
X
A
Y
B
P-4.6.3 Lap Joint Flange
tf
(a) A lap joint flange (see Figure P-4.6.3-1)
(1 ) allows the use of high-strength, carbon, or lowalloy steel flange material in services where high-alloy
pressure-boundary materials are required.
(2) allows the use of closely matching coefficients of
expansion of flange materials as described in (1) with
high-strength bolting such as SA-193 B7, SA-193 B16,
and SB-637 (Alloy N07718).
(3) is a superior flange style when the joint will be
subjected to rapid heat-up–cooldown temperature cycles.
This is because lap j oint flanges do not experience the
discontinuity forces and moments created during a
thermal cycle in the tapered-hub-type flange, which
result in an unwanted flange rotation cycle. Additionally,
the lap j oint flange is not in intimate contact with the
service fluid and hence the heating–cooling rate of the
flange assembly is retarded relative to service-fluid
changes, thereby minimizing the unwanted temperature
differentials between the flange and bolts.
(4) is suitable for lethal service application provided
the Category C j oint for lap j oint stub end meets the
requirement of ASME BPVC, Section VIII, Division 1 ,
Part UW, UW-2.
(b) The following are industry-accepted good practices
for use of lap joint flanges:
(1 ) Require the finished lap ring thickness to be a
minimum of 5 mm ( 3 ∕1 6 in.) greater than the nominal
wall thickness of the shell.
(2) Require that the laps be machined front and back
to provide parallel surfaces and surfaces normal to the axis
of the shell after all fabrication is complete.
O
Welding Neck
(b) allows butt-welded attachment to the shell (Category C location)
(c) allows radiographic examination of the Category C
butt joint
(d) provides the most flange rigidity for a given flange
thickness
(e) is suitable for lethal service application
P-4.6.2 Slip-On-Type Flanges
(a) Slip-on-type flanges (see Figure P-4.6.2-1) shall not
be used for lethal service application. See ASME BPVC,
Section VIII, Division 1, Subsection B.
(b) Slip-on-type flanges are double fillet welded to the
shell, thereby limiting the nondestructive examination to
either magnetic particle examination or liquid penetrant
examination.
(c) The abrupt transition of stress from the flange (or
flange hub) thickness to the shell via a fillet weld is not
favorable to services for which fatigue and brittle fracture
avoidance are governing design requirements.
(d) The pocket formed by face welds in a companion
j oint may create a liquid p ool and unequal thermal
stresses with resultant temporary leakage during the
heat-up cycle.
(e) The following are industry-accepted good practices
for use of slip-on-type flanges:
(1 ) Limit the use of slip-on-type flanges to systems
with design temperatures not exceeding 343°C (650°F).
(2) Avoid using carbon or low-alloy steel slip-ontype flanges on solid high-alloy shells. If such flanges
are used on solid high-alloy shells, the shell’s design
temperature should not exceed 23 2 °C (450°F) , unless
j ustified by complete stress analysis and accepted by
the user.
(3) Provide a 3-mm (1 ∕8 -in.) diameter vent through
the hub before welding both sides of the slip-on flange.
(4) Avoid using slip-on-type flanges for services
subject to moderate corrosion such as requiring a corrosion allowance in excess of 1.5 mm (1 ∕16 in.). Consider face-
Figure P-4.6.2-1
Slip-On-Type Flange
X
B
tf Y
O
Slip-On Welding
87
ASME PCC-1–2022
Figure P-4.6.3-1
Lap Joint Flange
GENERAL NOTE: Provide a minimum of four lugs on the shell for
each lap joint flange to permit the joint to be pried apart for
removing and replacing the gasket. The lugs for the lowermost
flange in a joint for which the flange ring is in a horizontal plane
will also support the flange when the joint is disassembled.
NOTE: (1) Radial lap width is measured from the toe ofthe lap-toshell attachment weld to the outer edge of the lap ring.
P-5 LEAKAGE PROBLEMS AND POTENTIAL
SOLUTIONS
Tables P-5-1 through P-5-5 provide recommendations
for diagnosing and resolving the following leak types:
(a) a leak during pressure test (see Table P-5-1)
(b) a leak during heat-up or initial operation (see
Table P-5-2)
(c) a leak corresponding to thermal or pressure upset
(see Table P-5-3)
(d) a leak after long-term operation (see Table P-5-4)
(e) a leak during shutdown (see Table P-5-5)
Lap Joint
(3) Provide lap-type flange-to-shell clearance of
3 mm (1 ∕8 in.) for nominal diameters up to and including
1 000 mm (40 in.). Larger nominal diameter flanges should
allow 5 mm (3 ∕16 in.) for flange-to-shell clearance.
(4) Configure the gasket-lap-flange design so that the
gasket load reaction on the lap (defined as G in ASME
BPVC, Section VIII, Division 1, Mandatory Appendix 2)
is as close as practicable to being coincident with the reaction of the flange against the back of the lap (taken as the
midpoint of contact between the flange and lap). Recommended radial lap widths are as follows:
Outside Diameter of Nozzle,
mm (in.)
P-6 REFERENCES
[1] Koves, W. J., “Design for Leakage in Flanged Joints
Under External Loads,” ASME 2005 Pressure Vessels
and Piping Conference, PVP2005-71254, Denver, CO,
July 17–21, 2005, DOI: 10.1115/PVP2005-71254
[2 ] Payne, J. R., “On the Operating Tightness of B1 6.5
Flanged Joints,” ASM E 2 0 0 8 Pressure Vessels and
Piping Conference, PVP2008-61561, Chicago, IL, July
27–31, 2008, DOI: 10.1115/ PVP2008-61561
[3] Bickford, J. H., An Introduction to the Design and Behavior of Bolted Join ts, Chapter 1 9, CRC Press, United
Kingdom, 1995
Radial Lap Width, mm (in.)
[Note (1)]
≤ 457 (≤18)
25 (1.00)
>457 to ≤914 (>8 to ≤36)
38 (1.50)
>914 to ≤1 523 (>36 to ≤60)
45 (1.75)
>1 523 (>60)
50 (2.00)
88
ASME PCC-1–2022
Table P-5-1
Leak During Pressure Test
Telltale Signs
Possible Causes
Potential Solutions
Some loose or near-loose bolts and/or gap
variation
Improper assembly
Use improved assembly procedures and
qualified assemblers. See section 10 and
Nonmandatory Appendix A.
Gap variation, excessive torque for bolts
mostly on one side
Excessive misalignment
Correct alignment to specification. See
section 6 and Nonmandatory Appendix E.
Excessive torque is required for some (or all) Incorrect bolt-nut class, damaged threads,
bolts, some loose or near-loose washers
yielded or deformed bolts
Replace all bolts/nuts to proper specification
and class. See Nonmandatory Appendix N,
para. N-3.
Some bolts galled or galling under nuts
(a) Replace all bolts. Consider different bolt or
nut materials (e.g., avoid stainless nuts on
stainless bolts or increase hardness
difference between them to exceed 50
HBW).
(b) Consider through-hardened washers. See
Nonmandatory Appendix M.
(c) Review lubricant selection and lubrication
practices. See section 8.
Gasket compressed unevenly around the
circumference or crimped between flange
facings
Gasket shifted off flange face (not centered)
(a) Reassemble joint with emphasis on gasket
location. See section 7.
(b) Use improved assembly procedures and
qualified assemblers. See section 10 and
Nonmandatory Appendix A.
Spiral windings are buckled inward, or
variation in gasket thickness is excessive
around the gasket perimeter
Gasket unevenly loaded
(a) Consider the inner gauge ring.
(b) Consider buckle-resistant gasket type.
(c) Improve gap measurement technique. See
para. 10(a)(2)(-d).
(d) Increase bolt load in smaller increments
and use more pattern (noncircular) passes
initially.
(e) Use improved assembly procedures and
qualified assemblers. See section 10 and
Nonmandatory Appendix A.
Flange facing damaged from weld spatter, tool Damage not noted in previous inspection or (a) Remachine to specification. See
Nonmandatory Appendix C.
dings, etc., confirmed by inspection
during assembly
(b) Improve inspection procedures and
techniques. See section 4.
Flange facing damaged from excessive
corrosion by highly corrosive media,
confirmed by inspection
Damage not noted in previous inspection or (a) Remachine to specification. See
during assembly
Nonmandatory Appendices C and D, and
ASME PCC-2, Article 305.
(b) Improve inspection procedures and
techniques. See section 4.
Flange ring warped or bent out of plane,
confirmed by accurate measurements
Damage not noted in previous inspection or (a) Remachine to specification. See
during assembly
Nonmandatory Appendices C and D, and
ASME PCC-2, Article 305.
(b) Improve inspection procedures and
techniques. See section 4.
89
ASME PCC-1–2022
Table P-5-2
Leak During Heat-Up or Initial Operation
Telltale Signs
Bolts are not tight on inspection
Possible Causes
Potential Solutions
Bolt load loss due to excessive initial gasket (a) Increase initial bolt load. See ASME BPVC,
creep during heat-up
Section VIII, Division 1, Mandatory
Appendix 2.
(b) Consider hot torque (if safe) during warmup.
(c) Increase joint flexibility by increasing
effective bolt length [see para. 9(b)(2)] by
using bolt extension collars or conical spring
washers that are clearly identified as such.
(d) Use a gasket with reduced relaxation
properties.
Leakage stops once operation is steady state Loss of bolt load due to excessive transient
differential component temperature
(a) Increase assembly bolt load.
(b) Increase gasket width.
(c) Increase joint flexibility by increasing
effective bolt length [see para. 9(b)(2)] by
using bolt extension collars or conical spring
washers that are clearly identified as such.
(d) Perform thermal-structural analysis to
evaluate transient flange and bolt
deformations as means to discover further
remedial actions.
(e) Consider replacing flanges with lap-type
flanges as a means to reduce flange–bolt
differential expansion.
Gap variation, some loose or near-loose bolts Improper assembly
Use improved assembly procedures and
qualified assemblers. See section 10 and
Nonmandatory Appendix A.
Excessive torque required for some (or all) Some bolts galled or galling under nuts
bolts, some loose or near-loose washers, gap
variation
(a) Replace all bolts. Consider different bolt or
nut materials (e.g., avoid stainless nuts on
stainless bolts or increase hardness
difference between them to exceed 50
HBW).
(b) Consider through-hardened washers. See
Nonmandatory Appendix M.
(c) Review lubricant selection and lubrication
practices. See section 8.
Spring hangers incorrect, support lift-off,
incorrectly placed restraints
Improper pipe support or restraint causing an (a) Check support and restraint system against
excessive bending moment
design.
(b) Analyze as-installed piping system thermal
and weight response with emphasis on
bending moment at flange joints.
(c) Correct any deficiencies.
Gasket compressed unevenly around the
circumference or crimped between flange
facings
Gasket shifted off flange face (not centered)
(a) Reassemble joint with emphasis on gasket
location. See section 7.
(b) Use improved assembly procedures and
qualified assemblers. See section 10 and
Nonmandatory Appendix A.
Spiral windings are buckled inward, or
variation in gasket thickness is excessive
around the gasket perimeter
Gasket unevenly loaded
(a) Consider the inner gauge ring.
(b) Consider buckle-resistant gasket type.
(c) Improve gap measurement technique. See
para. 10(a)(2)(-d).
(d) Increase bolt load in smaller increments
and use more pattern (noncircular) passes
initially.
(e) Use improved assembly procedures and
qualified assemblers. See section 10 and
Nonmandatory Appendix A.
Spiral windings are buckled
Poor gasket selection or design
(a) Consider the inner gauge ring.
(b) Use another, less soft gasket style.
(c) Consider buckle-resistant gasket type.
90
ASME PCC-1–2022
Table P-5-3
Leak Corresponding to Thermal or Pressure Upset
Telltale Signs
Possible Causes
Potential Solutions
Leakage stops or reduces once operation
returns to steady state
Loss of bolt load due to process thermal (or (a) Increase gasket width.
pressure) transients
(b) Increase assembly bolt load.
(c) Increase joint flexibility by increasing
effective bolt length [see para. 9(b)(2)] by
using bolt extension collars or conical spring
washers that are clearly identified as such.
(d) Consider operational changes that slow
heat or cool rates or reduce thermal swings.
(e) Consider replacing flanges with lap-type
flanges.
Leakage corresponds to external event and
generally stops on return to steady state
Sudden environmental changes (e.g., a rain
deluge)
(a) Increase assembly bolt load.
(b) Consider external shielding.
Table P-5-4
Leak After Long-Term Operation
Telltale Signs
Possible Causes
Potential Solutions
Gasket structure no longer flexible or
compliant, or filler missing
Gasket chemical degradation (chemical
decomposition, oxidation, etc.)
Change gasket type.
Spring hangers incorrect, support lift-off,
incorrectly placed restraints
Improper pipe support or restraint
(a) Check the support and restraint system
against design.
(b) Analyze as-installed piping system thermal
and weight response with emphasis on
bending moment at flange joints.
(c) Correct any deficiencies.
Bolts are not tight on inspection
Bolt load loss due to long-term gasket creep (a) Increase initial bolt load. See ASME BPVC,
Section VIII, Division 1, Mandatory
Appendix 2.
(b) Consider hot torque (if safe) during
warmup.
(c) Increase joint flexibility by increasing
effective bolt length [see para. 9(b)(2)]
considering bolt extension collars or conical
spring washers that are clearly identified as
such.
(d) Use a gasket with reduced relaxation
properties.
Bolts are not tight on inspection, obvious
gasket deterioration, gasket structure no
longer sound
Physical gasket degradation, gasket unsuitable Replace gasket with a type suitable for
for operating temperature
operating conditions.
Gasket structure is no longer sound (double Gasket physical degradation due to flange
jacket broken or windings buckled), marks
differential radial movement
on gasket surface corresponding to radial
flange face movement
GENERAL NOTE: Long-term operation = 1 or more months of operation.
91
(a) Remove all flange face nubbins.
(b) Replace gasket with a type capable of
taking radial shear and greater abrasion
such as spiral-wound, soft-faced metal core
with facing layers, or flexible graphite
reinforced with a metal interlayer insert.
See Nonmandatory Appendix C.
ASME PCC-1–2022
Table P-5-5
Leak During Shutdown
Telltale Signs
Possible Causes
Potential Solutions
Bolts are not tight on inspection
Bolt load loss due to long-term gasket creep (a) Increase initial bolt load.
together with differential component
(b) Consider start-up retorque (if safe).
cooling
(c) Consider different gasket types more
suitable for operating conditions.
Bolts are not tight on inspection, obvious
gasket deterioration, gasket structure no
longer sound
Physical gasket degradation, gasket unsuitable Replace gasket with a type suitable for
for operating temperature
operating conditions.
Bolts are not tight on inspection, obvious
Physical gasket degradation and loss of bolt
gasket deterioration, gasket structure no
load due to flange differential radial
longer sound (double jacket broken or
movement
windings buckled), marks on gasket surface
corresponding to radial flange face
movement
92
(a) Remove any flange face nubbins.
(b) Replace gasket with a type capable of
taking radial shear such as the first three
types listed in Nonmandatory Appendix C.
ASME PCC-1–2022
NONMANDATORY APPENDIX Q
CONSIDERATIONS FOR THE USE OF POWERED EQUIPMENT
Q-1 GENERAL GUIDANCE
Q-2.2 Benefits
This Appendix is intended to provide relevant background to additional considerations that can be required
when assembling pressure boundary bolted joints using
powered equipment. Powered equipment can include
hydraulic, electric, or pneumatic bolt-tightening tools.
Specific instructions regarding the use of powered equipment and safety considerations regarding the use of
powered equipment are not covered in this Appendix.
Guidance on the safe use and operation of powered equipment is generally provided by the equipment manufacturer.
Only commonly used assembly equipment is addressed
in this Appendix. Other specialized or custom equipment
may be available that could offer benefits or disadvantages
over the listed equipment. Such equipment is outside the
scope of this Appendix.
I n all cases for p owered equip ment, due to small
constant sources of applied load error, the accuracy of
the o b tained lo ad decreas es with lo w ap p lied b o lt
stress. This is one ofthe reasons for the minimum required
bolt stress, Sb min , in Nonmandatory Appendix O. The
Nonmandatory Appendix O limit should be adhered to;
otherwise the obtained bolt load can be significantly inaccurate (e.g., only half of that intended) . In addition, for
powered torque control, the obtained torque accuracy
is reduced at the up p er and lo wer extremes o f the
tool’s capable torque range. In addition, tool wear is
much higher at the maximum torque levels. Therefore,
th e s e to o l s s h o ul d n o rm al l y b e u s e d wi th i n th e i r
op timal accuracy range of 2 0 % to 8 0 % o f the total
torque range.
Pneumatic and electric torque wrenches are typically
much faster to use than hydraulic torque assembly.
Q-2.3 Disadvantages
Pneumatic and electric torque wrenches rely on a gear
system (torque multiplier system) and are therefore
inherently more likely to become inaccurate or out-of-calibration than hydraulic torque wrenches. The torque accuracy and s p eed o f us e may als o b e affected b y the
a va i l a b i l i ty o f s u i ta b l e a i r s u p p l y ( p re s s u re a n d
volume) in the case of pneumatic torque wrenches. Similarly, battery power can affect the torque accuracy and
speed of use for battery-powered tools.
Q-2.4 Accuracy and Use Considerations
Pneumatic and electric torque wrenches should be calibrated or verified to achieve the correct torque more
frequently than hydraulic torque wrenches. Alternatively,
they may be checked on the same frequency if the final
passes of the tightening procedure are completed using a
hydraulic torque wrench. This has the advantage of using
the faster method during the first passes when there is
s i gn i fi c a n t n u t m o ve m e n t an d th e m o re a c cu ra te
method during the final passes, where the nut movement
is minimal. To be used accurately, it is necessary to release
and not re-pull the trigger on some torque wrenches; once
they first stall, pulling the trigger can result in the additional load being applied beyond the target load.
Q-2.5 Assembly Procedure Considerations
Pneumatic and electric torque wrenches are used in the
same manner as manual torque wrenches. Similar to
manual methods, torque should be applied to the bolts
in the required pattern until nuts no longer turn, so as
to ensure that the required bolt load is obtained.
Q-2 PNEUMATIC AND ELECTRIC TORQUE
WRENCHES
Q-2.1 Description
Pneumatic and electric torque wrenches consist of an
air or electric motor connected to an assembly socket
through a reducing gear system. The gears allow both
reduction in speed and the multiplication of the motor
torque (torque advantage) . Air impact guns are not
included in this group of tools, since there is no accurate
control of the applied torque.
Q-3 HYDRAULIC TORQUE WRENCHES
Q-3.1 Description
Hydraulic torque wrenches use a small hydraulic cylinder to apply a torque to the tool via either a socket or a
cassette (link) . There are two common types of torque
wrenches: square drive and low profile. Square drive
93
ASME PCC-1–2022
wrenches offer the ability to cover a larger range of bolt
cation. The torque applied by the wrench is determined by
diameters by replacing a standard impact socket (similar
the hydraulic pressure applied by the pump. The pump
to a manual torque wrench) . Low profile wrenches require
pressure required is usually read from a table of pressure
less clearance around the nut and are easier to use in most
versus obtained torque for the particular wrench speci-
cases (due to the inherent alignment of the points of appli-
fication being used (required pressure is determined from
cation of torque and reaction of torque) . In addition, low
wrench geometry) . Similar to manual methods, torque
profile wrenches can be used with more stud protrusion
should be applied to the bolts in the required pattern
than the socket that is used with a square drive wrench.
until nuts no longer turn, so as to ensure that the required
bolt load is obtained.
Q-3.2 Benefits
Q-4 HYDRAULIC TENSIONERS
Hydraulic torque wrenches are relatively easily applied
(i.e., they are similar to manual torque wrenches in appli-
Q-4.1 Description
cation) and are capable of applying a wide range of torque
levels. Hydraulic torque wrenches are more effective for
A hydraulic tensioner is a small hollow hydraulic cyl-
the b reak- o ut o f l arge di ame te r b o lts (i . e . , th ey can
inder that threads onto the end of the bolt. Bolt load is
generate higher torque levels) .
applied to the bolt via hydraulic pressure in the cylinder.
Q-3.3 Disadvantages
Once the desired bolt load is obtained, the nut on the bolt
being tightened is spun down into contact with the flange
and the tensioner pressure is released, causing the bolt
Hydraulic torque wrenches are comparable to other
load to transfer to the nut. A portion of the originally
forms of torque application. Within the range of j oints
applied tensioner load is lost during the load transfer
that would be assembled by torquing versus tensioning
o nto th e nu t. Th i s i s cal l e d the n u t l o ad l o s s facto r
with 5 0 % or greater tensioner coverage, the assembly
(NLLF) . If less than 1 0 0 % tensioner coverage is being
time for hydraulic torque wrenches is generally longer,
used, there is additional loss of load when the second
and the bolt load variation is wider (due to inherent varia-
and any s ub s equent s ets o f b o lts are tightened. This
tion in nut factor of 2 0% or more, even with good control) .
lo s s i s due to addi tio nal j o int co mp o nent deflecti o n
However, the assembly time and bolt load variation for
( fl a n ge d e fo r m a ti o n a n d ga s ke t c o m p re s s i o n ) a n d
h yd r a u l i c to r q u e wr e n c h e s a r e wi th i n a c c e p ta b l e
results in lo ad reductio n on the previo us ly tightened
ranges for general use.
set of bolts. This load loss is called the bolt load loss
Q-3.4 Accuracy and Use Considerations
factor (BLLF) . In both cases, the amount of load lost is
proportional to the j oint component stiffness.
Hydraulic torque wrenches are typically used at torque
To co m p e n s ate fo r th e s e l o ad l o s s e s , th e ap p l i e d
levels over 68 0 N· m (5 0 0 ft- lb) , as the use of manual
te ns i o ne r p res s ure i s i ncre as e d fo r e ach p as s . Wi th
torque wrenches becomes difficult in some applications
1 00% tensioner coverage, only the NLLF is compensated
above that level. Below 680 N·m (5 00 ft-lb) torque, manual
for, which typically requires an increase in applied load in
to rqu e wre n ch e s are fas te r an d s i m p l e r to e m p l o y.
the range of 1 05 % to 15 0% of the desired final bolt target
H ydraulic to rque wrench co mp o nents are s ub j ect to
load. If the increased tension load to compensate for the
wear and deformation. Thus, the internal components
NLLF cannot be obtained (due to tensioner load capacity
require adequate lubrication to minimize load loss due
limits or j oint component yield limitations) , then either a
to tool friction. It is therefore necessary to periodically
lower target bolt load needs to be accepted or an alter-
calib rate o r verify the achieved to rque at an interval
native means of tightening should be used.
appropriate for the frequency of use. I f the wrench is
If less than 1 00% tensioner coverage is used, the load
found to be out of calibration, even after overhaul, the
applied in the initial passes is increased to compensate for
custom pressure-torque chart shall be used to ensure
both the NLLF and the BLLF, in order to reduce the amount
the target to rque is ob tained. The pres sure gauge o n
of time required to assemble the j oint. This increase in
the hydraulic pump shall also be calibrated periodically.
applied load is typically in the range of 1 1 0% to 1 5 0%
N O T E : T h e re i s n o t c u rre n tl y a s ta n d a rd fo r c a l i b ra ti o n
of the desired final bo lt target load. I n some cas es, it
frequency of powered torque wrenches. For purposes of infor-
may not b e po ssible to obtain the required load (due
mation, the calibration frequency for manual torque wrenches is
to insufficient tensioner load capacity or j oint component
1 2 months per ISO 6789.
yield limitations) . In those cases, the solution is to perform
Q-3.5 Assembly Procedure Considerations
additio nal tightening p as s es (no ting that many mo re
passes may be required if the load is not close to that
H yd rau l i c to rq u e wre n ch e s are u s e d i n th e s am e
required) .
manner as manual torque wrenches for j oint assembly.
The higher increased hydraulic pressure to compensate
Tool clearance and torque capacity shall be considered
for the NLLF and BLLF (for <100% tensioner coverage) is
when selecting the correct wrench for the required appli-
typ i cal l y te rm e d “p re s s u re A.” Th e l o we r i n cre as e d
94
ASME PCC-1–2022
hydraulic pressure to compensate for the NLLF is typically
termed “pressure B.” For example, in 5 0% tensioner
coverage, pressure A is applied to the first set of bolts
and then pressure B is applied to the second set. Pressure
B is then used to check that the required load has been
obtained (break-out test).
surface and will reduce the amount of NLLF by up to
5%. In general, to aid uniformity of assembly and disassembly, both ends of stud bolts should be lubricated prior
to assembly.
Q-4.2 Benefits
Availability of tensioning equipment for bolts less than
M27 (1 1 ∕8 in.) can be problematic, meaning that in general
only bolts greater than M24 (1 in.) are tensioned. In addition, the availability of sufficient tensioning equipment
and qualified operators may make it impractical to use
hydraulic tensioning as the default assembly method.
In all cases, the bolt shall extend a minimum of one
diameter above the nut to allow safe engagement of
the tensioner head.
(a) A general outline of the required procedure for
100% tensioner coverage follows:
(1 ) Pas s 1 a: I n acco rdance with manufacturer
i ns tructi o ns , fi t te ns i o n e rs to al l b o l ts p e r F i gure
Q-4.5-1. Follow equipment safety instructions, including
ensuring all tensioners are fully threaded onto the bolts
prior to applying any pressure, in order to prevent injury.
Ensure that each tensioner sits completely flat on the
flange; if there is any gap or if the tensioner face is not
parallel with the flange, this shall be fixed prior to
proceeding to tension or full load will not be achieved.
T e n s i o n th e b o l ts to 7 0 % o f a s s e m b l y l o a d a n d
measure flange gaps in accordance with Nonmandatory
Appendix J, para. J-2.
(2) Pass 1b: Tension the bolts to 105% to 150% of
assembly load, with a pressure multiplier equal to 1∕NLLF,
as determined per the tables for standard flanges and the
gasket being used or as determined by calculation (see
ref. [1] ) . The required hydraulic pressure to obtain the
target bolt load is determined using either the manufacturer’s load versus the applied pressure table or the
following calculation:
Q-4.5 Assembly Procedure Considerations
Hydraulic tensioning can be very quick and accurate
when applied correctly [generally for studs M50 (2 in.)
and larger] . It also tends to improve stud life (less risk
in bolt reuse) due to lack of torsion and thread galling
(since the nut is wound down in the unloaded condition).
B o l t r e p l a c e m e n t s h o u l d s ti l l b e e v a l u a te d p e r
N onmandato ry Ap p endix N . Additionally, hydraulic
te n s i o n i n g a p p l i e s th e l o a d s i m u l ta n e o u s l y i n a
unifo rm manner aro und the j o int, which res ults in
more even gasket compression and less elastic interaction,
thus reducing the likelihood of gasket damage during
assembly.
Q-4.3 Disadvantages
Hydraulic tensioning relies on the accurate estimation
or calculation of the NLLF and BLLF. If these loss factor
values are not determined with a reasonable level of accuracy, then the method may be less accurate than torque
control. This is particularly the case with short bolts
(generally considered where the length to no minal
diameter ratios are less than 5) on a stiff flange. In addition, the required load may exceed joint component limits.
The use of bolt tensioners requires that the threaded
portion of the bolt extend at least one bolt diameter
beyond the outside nut face on the tensioner side of
the joint.
Q-4.4 Accuracy and Use Considerations
The load loss factors should be accurately determined
(example guidance may be found in ref. [1] ) or the final
obtained bolt load verified for at least a couple of bolts
from each pass using elongation measurement (ultrasonics, bolts with in-built load measurement, or extensometer tools), with the applied load adjusted to ensure
the desired final load is obtained (typically, the measured
bolt load can be achieved within ±5% of the target load).
The method is more accurate (and much quicker to
perform) if a higher percentage of tensioner coverage
is employed. It should be ensured that the tensioner
bridge sits flat on the back of the flange. If it rides up
on the hub radius, or similar, then the tensioner will
not be aligned with the bolt during the application of pressure, resulting in a significant (10% to 30%) loss ofapplied
bolt load. The tensioning procedure should include repetition of the tensioner pressure and tightening of the nut
prior to the removal of the tensioners from the bolt. This
helps to preload the threads and nut-to-flange seating
required hydraulic pressure
=
target bolt stress
× bolt area
tensioner pressure area
Note that the bolt area used should be the same as that
used for calculation ofthe target bolt stress, i.e., either root
area or tensile area per Nonmandatory Appendix H). For
100% tensioner coverage, use the pressure B factor ifboth
pressure A and pressure B are listed. Remeasure the flange
gaps for conformance to Nonmandatory Appendix J, para.
J-2. To minimize relaxation, cycle the tensioner pressure
from zero to full load several times, tightening the nut
during each cycle until the additional nut movement is
minimal (< 1 ∕16 of a flat) prior to removing the tensioners
(b) A general outline ofthe required procedure for 50%
tensioner coverage follows:
(1 ) Pas s 1 a: I n acco rdance with manufacturer
instructions, fit tensioners to bolts per Figure Q-4.5-2 .
Follow equipment safety instructions, including ensuring
95
ASME PCC-1–2022
Figure Q-4.5-1
24-Bolt, 24-Tool Example
23
24
1
2
22
Pass 1 a — 70% of assembly load simultaneously on all
bolts, take gap measurements.
3
21
4
5
20
6
19
Pass 1 b onward — 1 05% of assembly load simultaneously
on all bolts, take gap measurements. Repeat without gap
measurement until no movement occurs during
tightening of the nut.
7
18
8
17
16
9
10
15
14
13
12
11
minimum to full load several times, tightening the nut
during each cycle until the additional nut movement is
minimal prior to removing the tensioners.
(4) Pass 2 onward: Place at least four tensioners onto
the first set of bolts. Stroke the tensioners to 100% of
assembly load (pressure B) . If the nuts turn by hand,
then all of the first set of bolts shall be retensioned to
1 0 5 % to 1 5 0 % o f the as s emb ly lo ad (p res s ure B ) .
Repeat this check on the next set of bolts until the nut
movement is less than the specified limit.
(c) Procedures for less than 50% coverage are similar
to the 50% coverage procedure, with the addition of many
more passes and check passes.
all tensioners are fully threaded onto the bolts prior to
ap p lying any p res s ure, in o rde r to p re vent inj ury.
Ensure that each tensioner sits completely flat on the
flange; if there is any gap or if the tensioner face is not
parallel with the flange, this shall be fixed p rior to
proceeding to tension or full load will not be achieved.
(2) Pass 1b: Tension the bolts to 110% to 200% of
assembly load (pressure A) , with pressure multiplier
equal to [(1 + B LLF) ∕N LLF] , as determined p er the
tables for standard flanges and the gasket being used
or as determined by calculation (see ref. [1] ). The required
hydraulic pressure to obtain the target bolt load is determined using either the manufacturer’s load versus the
applied pressure table or the following calculation:
required hydraulic pressure
=
target bolt stress
Q-5 ESSENTIAL ELEMENTS OF TORQUE TOOL
PERFORMANCE
× bolt area
tensioner pressure area
Q-5.1 Torque Calibration
Note that the bolt area used should be the same as that
used for calculation ofthe target bolt stress, i.e., either root
area or tensile area per Nonmandatory Appendix H). Use
pressure A for this pass. Measure the flange gaps for
conformance to Nonmandatory Appendix J, para. J-2 .
To minimize relaxation, cycle the tensioner pressure
from zero to full load several times, tightening the nut
during each cycle until the additional nut movement is
minimal (< 1 ∕16 of a flat) prior to removing the tensioners.
(3) Pass 1c onward: Tension the second set ofbolts to
105% to 150% of assembly load (pressure B factor), as
determined per the tables for standard flanges and the
gasket being used or as determined by calculation (see
ref. [1] ). Remeasure the flange gaps. To minimize relaxation, it is advisable to cycle the tensioner pressure from
(a) Calibration Procedure. The calibration procedure
requires direct measurement and mapping of a serialnumbered tool’s torque output on a predetermined
bolted joint with a certified torque transducer.
(b) Calibration Frequen cy. ISO 6789-2 specifies an
annual calib rati o n require ment fo r manual to rque
wrenches, and it is good practice to also follow this
annual fre que ncy re qui re me nt, at a mi ni mum, fo r
powered-equipment calibration.
96
ð 22 Þ
ASME PCC-1–2022
Figure Q-4.5-2
24-Bolt, 50% (12-Tool) Example
24
1
23
2
3
22
Pass 1 a — 70% of assem bl y l oad si m u l tan eou sl y on every
secon d bol t, m easu re g aps.
4
1
21
Pass 1 b on ward — 1 1 0% to 200% of assem bl y l oad
5
20
19
si m u l tan eou sl y on th e sam e bol ts, m easu re g aps.
6
Pass 1 c on ward — 1 05% to 1 50% of assem bl y l oad
si m u l tan eou sl y on th e secon d bol ts, m easu re gaps.
18
7
Pass 2 on ward — 1 00% of assem bl y l oad on th e n ext set
8
17
of bol ts, reten si on an d rech eck n ext set of bol ts i f
si g n i fi can t n u t m ovem en t occu rs.
16
9
15
10
14
11
13
12
(b) Verification Frequency. Verification can be implemented in a very wide range of time intervals, and verifi c a ti o n s h a l l b e p e r fo r m e d b a s e d o n th e u s e r ’ s
requirements, between calibration intervals. Analysis
of verification records will identify changes over time
and is a powerful method of identifying tools that have
been misused and abused.
(c) Results ofVerification . Tools that pass a verification
test are likely within specification, although this is not
guaranteed. H o wever, a succes sful verificatio n test
provides confidence that the tool is still performing as
intended and may justify an extension of the recalibration
date. A verification program can be a very effective tool in
isolating and preventing issues related to tool performance and can supplement the need for more frequent
recalibration of equipment.
If a tool fails a verification test it shall be clearly marked
as out of calibration and taken out of service and shall be
repaired, and recalibrated.
Q-5.2 Tool Verification
(a) Methods of Verification . Verification should not be
mistaken for calibration as it is a function test and confirmation ofperformance that can be performed through two
main methods.
(1) Torque Verification . Torque verification is a spot
check done at a point, or potentially a series ofpoints along
the calibration curve on either a proven calibration stand
or verification device. It is used to quickly verify that
outside factors haven’t contributed to the degradation
of tool performance by comparing the results of the verification test with the original calibration result. This check
should be within the rated accuracy ofthe torque wrench if
performed on the original calibration equipment. I f
checked with a secondary appropriate measurement
system, this test should be within ±1 0% to eliminate
the gross outliers. The verification process must be as
representative as possible of the actual application in
both sequence and scale.
(2) Load Verification . Load verification measures the
actual clamping force generated in the fastener after the
application of torque is complete. This verification can be
done in the field, directly on a B16 pressure boundary
bolted flange for example. The load in the bolt can be
meas ured s everal different ways including b ut no t
limited to ultrasonic elongation, use of a load cell, or
lo ad indicating s tuds . With p ro p er lub ricatio n and
go o d h ard ware th e to o l s s h o ul d cre ate b o l t l o ads
wi th i n ± 2 0 % o f th e targe t val ue . Th e ve ri fi cati o n
process must be as representative as possible of the
actual application in both sequence and scale.
Q-5.3 Documentation
D ocumentation of the calibration and verification
should include the following:
(a) model name and the specific serial number of the tool
being tested
(b) input variables (hydraulic or air pressure, voltage,
machine setting, etc.) being measured against the torque
output
(c) all sample points tested
(d) date and location of the testing, and the name and
employer of the individual conducting the testing
(e) serial number and uncertainty of the certified measurement system
97
ASME PCC-1–2022
Q-6 REFERENCE
[1 ] Brown, W.,“Hydraulic TensionerAssembly: Load Loss Fa
ctorsandTargetStress Limits,”ASME 2 01 4PressureVesse
ls and PipingConference, PVP2 014-2 8685, Anaheim, CA, J
uly 2 0–2 4, 2 014, DOI: 1 0.11 1 5 /PVP2 01 4-2 8685
98
ASME PCC-1–2022
NONMANDATORY APPENDIX R
ASSEMBLY RECORDS MANAGEMENT
R-2.2 Content and Types of Joint Assembly
Records
R-1 PURPOSES OF JOINT ASSEMBLY RECORDS
Jo int ass embly reco rds serve the follo wing three
purposes:
(a) Quality Control. Joint assembly records document
the name and actions of each individual responsible
for a particular portion of the j oint assembly process.
Maintaining a record of the individual’s identity and
actions increases the accountability of the individual.
(b) Joint History. Joint assembly records document past
j oint assembly parameters, observations made during
joint assembly, and lessons learned. This information is
useful if the joint leaks during operation or an assembler
needs guidance during future assembly of the joint.
(c) Assembly Practices. Joint assembly records document all joint-specific practices or any deviations from,
changes to, or comments or observations about the
site assembly procedure. The user can use the gathered
data to update the assembly procedure before the next
joint maintenance activity.
Users should decide the level of detail to record in the
assembly records based on their own needs and resources.
Due to the large number of pressure-boundary bolted
j oints assembled during construction and maintenance
activities, it may not be practical to maintain a record
of all j oint assembly parameters. To this end, the user
may conduct a j oint criticality analysis using standard
risk-based methods to assess both the likelihood and
consequence of failure for any given joint.
After determining a joint’s risk level, the user should
decide the extent of record keeping for that j oint and
the re te nti o n p e ri o d fo r th e re co rd . B as e d o n th e
j oint’s risk level, the user typically follows one of the
following two paths:
(a) For joints deemed high risk, the assembler typically
completes a long assembly record such as shown in
Figure R-2 .2 -1 , and the user archives the form until
the next assembly.
(b) For lower-risk j oints, the assembler typ ically
c o m p l e te s th e s h o rte r re c o rd typ e s s h o wn i n
Figures R-2.2-2 through R-2.2-4.
Joints ofall risk levels may use a multipart tear-offtag as
shown in Figure R-2.2-4.
The short and medium-length records and multipart
tear- o ff tags are typ ically dis carded after s tart- up .
Thes e do cuments facilitate quality co ntro l o f j o int
assembly [see para. R-1 (a) ] but do not capture j oint
a s s e m b l y p a ra m e te rs o r o b s e rva ti o n s [s e e p a ra .
R-1(b)] and therefore have limited long-term use.
R-2 MAINTENANCE OF JOINT ASSEMBLY
RECORDS
R-2.1 Unique Identification of Each Joint
The first step in maintaining joint assembly records is to
identify each j oint uniquely. Each j oint should have a
unique identifier as s o ciated with a marking o r tag
system. The unique identification of each j oint serves
the following three purposes:
(a) Identification . The unique identifier enables an
assembler to identify the correct joint before beginning
any joint maintenance activity.
(b) Storage. The unique identifier enables the storage
of assembly records.
(c) Hazard Mitigation . The unique identifier minimizes
the potential hazards associated with the disassembly,
assembly, and tightening of the wrong joint.
NOTE: Avoid the tendency to provide or request too much information on the joint assembly record. The joint assembly record
should not be considered a substitute for written assembly
procedures or assembler qualification.
99
ð 22 Þ
ASME PCC-1–2022
Figure R-2.2-1
Example Long Assembly Record
Joint Identification:
Plant name:
Joint description/number:
Equipment/Dwg. no.:
Joint Description:
Diameter:
Gasket type and materials:
Gasket size (O.D., I.D., and thickness):
Bolt/nut specification:
Washer description:
Pressure rating:
Bolt size:
Bolt length:
Assembly Description:
Disassembly procedure required? Yes / No
Assembly method to be used:
Target assembly bolt stress:
Torque or tension setting required:
Assembly retorque required? Yes / No
Lubricant to be used:
Other special instructions:
Keep failed gasket? Yes / No
Retorque torque value:
Tool Identification:
List tool and pump (if applicable) unique calibration identifiers:
Joint Assembly Sign-Off:
Joint Assembly Parameter Records:
(1 ) Disassembled flange inspected
(2) Gasket inspected pre-install
(3) Bolt pre-install (free-running)
By:
Sign:
(4) Joint alignment
By:
Sign:
(5) Bolts lubricated
By:
Sign:
(6) Joint snug tightened
By:
Sign:
(7) Joint 1 00% assembled
By:
Sign:
(8) Joint leak tested
By:
Sign:
(9) Final QC sign-off
Sign:
Date:
Nut/washer bearing surface condition:
Flange finish and flatness:
Max. radial defect:
Defect depth:
Max. run-out:
Max. warp:
Joint alignment:
Max. axial gap:
Max. alignment load:
Joint in-process alignment:
Max. gap difference @ snug:
Max. gap difference @ tight:
Final pump pressure used:
Joint leak test:
Test pressure
Action taken if leaked:
Leak: Yes / No
Notes/Problems:
Return completed record to
100
(Name)
ASME PCC-1–2022
Figure R-2.2-2
Example Short Assembly Record
Date of installation:
Gasket description:
Final torque used:
Joint assembled
By:
Joint inspected
By:
Sign:
Sign:
Notes/Problems:
Return completed record to
(Name)
101
ASME PCC-1–2022
Figure R-2.2-3
Example Medium-Length Assembly Record
FRONT
BACK
Joint Identification:
Joint Assembly Sign-Off:
Plant name:
Equipment/Dwg. no.:
Joint description no.:
(1 ) Disassembled flange inspected
(2) Gasket inspected pre-installation
(3) Bolt pre-install (free-running)
By:
Sign:
(4) Joint aligned
By:
Sign:
(5) Bolts lubricated
By:
Sign:
(6) Joint snug tightened
By:
Sign:
(7) Joint 1 00% assembled
By:
Sign:
(8) Joint leak tested (pressure =
By:
Sign:
(9) Final QC sign-off
Sign:
Date:
Joint Description:
Diameter:
Pressure rating:
Gasket type/size:
Bolt/nut specification:
Bolt size and length:
Washer description:
Assembly Parameters:
Assembly method:
Assembly bolt stress:
Lubricant used:
Assembly torque:
Pump pressure:
Notes/Problems:
Tool Identification:
List tool calibration identifiers:
Return completed record to
102
(Name)
)
Figure R-2.2-4
Example Multipart Tear-Off Tag
ASME PCC-1–2022
103
GENERAL NOTE: Multipart tag courtesy of Regal Tag Global, Ltd., Little Barford, United Kingdom.
ASME PCC-1–2022