Air-Cooled Heat Exchangers
INTERNATIONAL
PRACTICE
IP 6-4-1
Page 1 of 6
(This practice is appropriate for attachment to Inquiry or Purchase Document)
Rev. 0
March 1998
Changes shown by
THE FOLLOWING PARAGRAPH NUMBERS REFER TO API STANDARD 661, 4TH EDITION, NOVEMBER
1997, TITLED, “AIR-COOLED HEAT EXCHANGERS FOR GENERAL REFINERY SERVICES,"
WHICH IS PART OF THE INTERNATIONAL PRACTICE
SECTION 1 - SCOPE
I
1.0
I
1.1
1.1.1
SCOPE
(Exception) - This practice covers the design, materials, fabrication, inspection, testing, and
preparation for shipment of air-cooled heat exchangers except those which are integral radiators for
equipment - such as a packaged air compressor unit. All paragraphs in this practice amend those of
API-661 unless specifically noted. For user convenience, the beginning of each paragraph in this IP
is noted as follows:
(Addition) - This note means that the paragraph specifies additions to the corresponding API
paragraph.
(Exception) - This note means that the paragraph completely replaces the corresponding API
paragraph.
(New) - This note means that the paragraph does not appear in API Standard 661 and denotes
new requirements.
GENERAL
(Addition) When the tube bundles are constructed for use at a location where the ASME Code is not
mandatory, it shall be noted, on the ASME Code forms, that the bundle does not carry an ASME code
symbol.
SECTION 2 - REFERENCED PUBLICATIONS
I
2.0
REFERENCED PUBLICATIONS
2.1
(Addition) Table 1 lists the documents that shall be used with this IP in addition to those listed in API
Standard 661.
TABLE 1
PRACTICES
IP 2-1-1
IP 5-1-1
IP 5-3-1
IP 16-9-1
Plant Noise Design Criteria
Pressure Vessels
Hydrostatic Testing of Unfired Pressure Vessels
A-C Motors
IP 18-7-1
IP 18-10-1
IP 18-12-1
IP 19-1-1
IP 20-1-1
Welding Procedures
Additional Requirements for Materials
Positive Material Identification
Paint and Protective Coatings
Inspection of Equipment and Materials
STANDARDS
API Standard
API 661
Air-Cooled Heat Exchangers for General Refinery Services
ANSI Standards
A12.1
Safety Requirements for Floor and Wall Openings, Railings and Toeboards
A14.3
Safety Requirements for Fixed Ladders
I
2.1.1
(Addition) Table 2 lists the documents that shall be used with this IP if so specified by the Purchaser.
THIS INFORMATION FOR AUTHORIZED COMPANY USE ONLY
EXXON RESEARCH AND ENGINEERING COMPANY — FLORHAM PARK, N.J.
IP 6-4-1
Air-Cooled Heat Exchangers
Page 2 of 6
Rev. 0
March 1998
(This practice is appropriate for attachment to Inquiry or Purchase Document)
INTERNATIONAL
PRACTICE
TABLE 2
PRACTICES
IP 3-16-1
IP 4-1-3
IP 10-7-1
IP 18-3-2
Flanges, Gaskets, Bolting and Fittings
Design Loads for Structures
General Purpose Steam Turbines
Statically Cast Steel and Alloy Pressure Containing
Parts, and Tube Supports, for Fired Heaters
IP 18-4-1 Postweld Heat Treatment of Equipment Handling
Alkaline Solutions
IP 19-2-1 Weld Overlay and Integrally Bonded Cladding
IP 19-7-1 Protection of Stainless Steel During Fabrication,
Shipping, Storage and Field Construction
CODES AND STANDARDS
ASME Codes
Section V
Section VIII
ASME Standard
Nondestructive Examination
Pressure Vessels, Division 1
B16.1
Cast Iron Pipe Flanges and Flanged Fittings,
Class 25, 125, 250, and 800
ASTM Standard
D 2000
Rubber Products in Automotive Applications
SECTION 4 - PROPOSALS
S,E
O
4.2
4.2.8
4.2.9
VENDOR'S RESPONSIBILITIES
(Exception) The proposal shall include noise level data per IP 2-1-1.
(Exception) The proposal shall include characteristic performance curves for fans.
SECTION 5 - DOCUMENTATION
5.1
APPROVAL INFORMATION
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5.1.1
o.
R
5.1.5
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I
5.2
5.2.3
5.2.4
(New) The outline drawings for each air-cooled heat exchanger shall contain completed
Table 3 of this IP.
(Exception) Welding procedures and qualifications shall be submitted for approval to the
Purchaser.
FINAL RECORDS
(New) Bulleted items in 5.2.1 of API-661 shall be furnished.
(New) Header details including metal thickness, internal header dimensions, pass partitions,
stiffeners and tube layout, shall be provided. If the entire header thickness is increased to provide
necessary reinforcement for nozzles, the thickness for reinforcement shall be noted on the header
drawing.
SECTION 6 - DESIGN
M
6.1.1
6.1.1.12
6.1.5
R
R
6.1.6
6.1.6.2.7
6.1.9
6.1.9.8
(New) The gasket contact surfaces of clad exchangers shall have at least 1/8 in. (3 mm) nominal
thickness of cladding.
HEADERS
(Exception) Through bolts shall be used wherever practical in the design.
NOZZLES AND OTHER CONNECTIONS
(d) (Exception) A fabricated transition approved by Owner's Engineer.
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6.1.9.12
(b)
M
6.1.5.5
GENERAL REQUIREMENTS
(Addition) When exchanger can operate below 120°F (49°C) including upsets and start-up conditions,
the lowest possible metal temperature will be specified by the Owner.
CORROSION ALLOWANCE
(Addition) The use of proprietary couplings must be approved by the Owner's Engineer.
THIS INFORMATION FOR AUTHORIZED COMPANY USE ONLY
EXXON RESEARCH AND ENGINEERING COMPANY — FLORHAM PARK, N.J.
Air-Cooled Heat Exchangers
Page 3 of 6
INTERNATIONAL
PRACTICE
O,M
6.1.9.16
O
6.1.9.17
O
6.1.9.23
M
6.1.11
6.1.11.13
(This practice is appropriate for attachment to Inquiry or Purchase Document)
d.
e.
M
M,S
6.2.2
6.2.2.1
6.2.3
6.2.3.6
O
S
6.2.3.11
6.2.3.15
I
S
6.2.7
6.2.7.1.1
6.2.7.2.1
S,E
S
R
I
O
6.2.7.3
6.2.8
6.2.8.2.1
6.2.8.4.1
6.2.9.1
March 1998
Tubes of extruded fin type shall not be used for design temperatures exceeding 500F (260C).
Tubes of overlapped footed tension wound fin type shall not be used for design temperatures
exceeding 300F (150C).
Tubes of footed tension wound fin type shall not be used for design temperatures exceeding
300F (150C).
Tubes of spiral groove footed fin type shall not be used for design temperatures exceeding 500F
(260C). The groove shall be per sub Item 1 above for mechanically embedded fins. The fin foot
shall be extruded in to the groove a minimum depth of one-half the fin thickness  0.002 in.
( 0.05 mm).
f.
6.1.11.14
6.2
6.2.1.1
Rev. 0
(Exception) If chemical cleaning connection is specified, it shall be provided per the following
guidelines:
a. The minimum size shall be NPS 2.
b. Connections shall be installed only in nozzles of NPS 4 and larger. For smaller nozzles,
connections shall be made in the piping by the Purchaser, and the proper note shall be placed in
the manufacturer's drawings.
c.
Connections shall be installed horizontally.
d. For bundles in series or series-parallel arrangement, only 1 chemical cleaning connection need
be provided in the inlet nozzle and 1 in the outlet nozzle of each series group.
(Exception) A thermowell connection (NPS 1) and a pressure gage connection (NPS 3/4) shall be
located in at least one inlet and outlet nozzle, except for intermediate nozzles in stacked bundles.
(New) Where freezing can occur, each pass of each header shall be capable of being vented and
drained. Drains are to be plugged couplings unless process reasons dictate a valved drain, which
shall be specified by the Purchaser.
TUBES
(New) Tube Types
a. Tubes of mechanically embedded fin type shall not be used for design temperatures exceeding
750F (400C).
b.
c.
M
IP 6-4-1
Tubes of tension would fin type shall not be used for design temperatures exceeding 250F
(120C). Tubes of tension wound fin type are prohibited in steam condensing service.
g. Fin end of tension wound fins shall be secured by rivet, screw, or staple fasteners.
(New) Each finned section shall be made from a single length of tube with no circumferential welds.
AIR-SIDE DESIGN
(Exception) The Purchaser shall specify the meteorological data per API-661 Checklist and location
of air-cooled heat exchangers in relation to adjacent buildings and equipment.
NOISE CONTROL
(Exception) Noise level data requirements shall satisfy the IP 2-1-1 requirements.
FANS AND FAN HUBS
(Addition) Fan orifice ring attachments that reduce fan tip clearance shall be attached by throughbolts.
b. (Exception) Each pneumatic actuator shall be equipped with a positioner.
(Addition) Fan hub assemblies with pneumatically actuated, automatically controlled pitch
adjustment shall not be used on induced draft units with inlet fluid temperature exceeding 275F
(135C).
DRIVERS
(Exception) Vendor shall furnish all drive equipment.
(Exception) Motors shall be per IP 16-9-1. Motor enclosures shall be appropriate for the area
classification and environmental exposure which Vendor shall request from the Purchaser.
(Exception) Steam turbine drivers shall be per IP 10-7-1.
COUPLINGS AND POWER TRANSMISSIONS
(Exception) Belt drives shall be high-torque positive drive design, or equivalent.
(Addition) Only for installations within the USA.
(Exception) Vibration cutout switches shall not be provided.
THIS INFORMATION FOR AUTHORIZED COMPANY USE ONLY
EXXON RESEARCH AND ENGINEERING COMPANY — FLORHAM PARK, N.J.
IP 6-4-1
Air-Cooled Heat Exchangers
Page 4 of 6
Rev. 0
March 1998
O
O
6.2.10
6.2.10.16
6.2.10.20
O
O
6.2.10.23
6.2.10.25
O
6.2.10.26
M
6.3
6.3.1.5
S,M
M
6.3.2.2
6.3.3
6.3.3.1
6.3.5
(This practice is appropriate for attachment to Inquiry or Purchase Document)
INTERNATIONAL
PRACTICE
LOUVERS
(Exception) A positioner shall be provided at each actuator.
(Addition) Manual operation by levers or chain operators shall not require application of a force
exceeding 100 pounds (45 kg).
(Exception) All requirements apply to both parallel and opposed action louvers.
(New) Pin type retainers shall be used to maintain manual control-levers for louvers in a set position.
Butterfly type locking nuts are not acceptable.
(New) All linkage joints are to be through bolted or pinned. Friction type joints are not acceptable.
The bolting or pinning shall be done after final linkage adjustment.
STRUCTURAL DESIGN
(Exception) Tube bundles shall be removable without removing the platforms. For forced draft
design, bundles shall be removable without separately supporting or dismantling the fan plenum, or
platforms and without disturbing the structure or adjacent bays.
(Exception) Vendor shall verify compliance to vibration limits by shop test.
STRUCTURAL DESIGN LOADS AND FORCES
(New) The requirements of IP 4-1-3, “Design Loads for Structures,” supersede any pertinent
requirements in the Section 6.3.3 of API-661.
MECHANICAL ACCESS FACILITIES
O
6.3.5.1
(Exception) Platforms shall be provided to serve inlet and return headers if the elevation of the
bottom header is more than ten (10) feet (3 m) above grade.
M
6.3.5.2
(Exception) The layout and sizing of platforms to serve driver and fan assemblies shall permit
access to all components.
S
S
6.3.5.4
6.3.5.5
S
S
6.3.5.5.3
6.3.5.8
(Exception) Grated or expanded metal shall not be used.
(Exception) Ladders, guard railings, toe plates, safety cages and similar items shall be constructed of
steel per ANSI A12.1 and A14.3. (The requirement to comply with OSHA regulations applies only for
installations within the U.S.A.)
(Exception) Ladders over 6 feet (2 m) shall provide side-step access to platforms.
(New) Velocity recovery stacks over 4 ft (1.2 m) high shall be provided with a hinged access door
approximately 2 ft by 2 ft (600 x 600 mm).
SECTION 7 - MATERIALS
I
7.1.1
S
S
S
7.1.3
7.1.11
7.1.12
S
7.3.2
(Addition) Proposals to use materials having a specified maximum tensile strength greater than
90,000 psi (620 MPa) at room temperature shall be submitted to Purchaser for approval by Owner's
Engineer.
(Exception) Cast iron pressure components shall not be furnished.
(New) Nuts larger than 1/2 inch (13 mm) shall not be machined from barstock.
(New) In wet H2S service, carbon steel components used for heat exchangers that are not fully
lined shall meet the following requirements:
a. All pressure containing components fabricated of plate shall be manufactured and tested per
Par. 8.2.3 (below) for resistance to Hydrogen Induced Cracking.
b. The steel shall be supplied in the normalized condition.
(Addition) Plastic fan blades shall not be exposed to outlet air temperature above 200°F (93°C).
SECTION 8 - FABRICATION
R
S
8.1.1.1, 8.1.1.2, 8.1.1.3 (Exception)
Welding procedures shall be per IP 18-7-1.
8.1.1.5
(New) For services with an operating condition of a hydrogen partial pressure above 100 psia (690
kPa), the space between any attachment and the header shall be vented using a 1/8 in. (3.2 mm)
diameter drilled hole.
THIS INFORMATION FOR AUTHORIZED COMPANY USE ONLY
EXXON RESEARCH AND ENGINEERING COMPANY — FLORHAM PARK, N.J.
IP 6-4-1
Air-Cooled Heat Exchangers
INTERNATIONAL
PRACTICE
Page 5 of 6
(This practice is appropriate for attachment to Inquiry or Purchase Document)
Rev. 0
March 1998
8.2
POSTWELD HEAT TREATMENT
S
8.2.3
(New) In wet H2S service, fabrication shall meet IP 5-1-1 requirements.
S
8.2.4
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8.2.5
R
8.3
8.3.1.2
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8.3.4.4
R
8.5
8.5.3
(New) Equipment in Caustic, Amine or Carbonate service shall be postweld heat treated as outlined in
IP 18-4-1.
(New) Welding on the base metal (including such items as repairs to base metal) shall be completed
and accepted by the inspector prior to postweld heat treating (PWHT).
TUBE-TO-TUBE SHEET JOINTS
(Addition) Tube hole diameter and tolerances for austenitic stainless steel tubes shall be “special
close fit" per Table 2 of API-661.
(New) Expanded tubes shall be welded to the headers for hydrogen service over 1000 psig (6900
kPa) or over 1000°F (540°C).
THREAD LUBRICATION
(New) Plugs shall be coated with a nickel based colloidal thread lubricant.
SECTION 9 - INSPECTION, EXAMINATION AND TEST
S
9.2
9.2.20
S
9.2.21
S
9.2.22
QUALITY CONTROL
(New) Any cast steel and cast alloy steel headers or nozzles shall conform to the INSPECTION
AND TESTING requirements of IP 18-3-2.
(New) A pilot casting for each type in an order shall be examined radiographically per the
INSPECTION AND TESTING requirements of IP 18-3-2.
(New) Spot examination by sectioning is prohibited.
S
9.2.23
(New) In wet H2S service, inspection and testing shall meet IP 5-1-1 requirements.
S
9.3
9.3.7
S
9.5
9.5.3
PRESSURE TEST
(Exception) When other types of tests, such as helium test, are specified, the techniques of
measurement and required sensitivity shall be submitted for approval by Owner's Engineer prior to
fabrication.
NAMEPLATES
(Addition) The nameplate shall also be marked with the Minimum Hydrostatic Test Temperature and
the MDMT.
SECTION 10 - PREPARATION FOR SHIPMENT
C
C
C
S
10.1.4
(New) Plywood or some comparable material shall be used to protect exposed finned sections from
mechanical damage during shipment and storage.
10.1.5
(New) If specified, a complete set of spare cover plate gaskets, or five percent spare tube access plug
gaskets shall be furnished. Cover plate gaskets and plug gaskets shall be boxed separately and
clearly identified on the box exterior.
10.2.
SURFACES AND FINISHES
10.2.1, 10.2.3, 10.2.4 (Exception)
The surface preparation and type of paint primer to be used shall be per IP 19-1-1 which supersedes
the requirements of these 3 paragraphs.
10.3
IDENTIFICATION, CONDITIONING, AND NOTIFICATION
10.3.5
(New) No exchanger shall be shipped without approval of the Owner or of the Owner's
Representative.
SECTION 11 - SUPPLEMENTAL REQUIREMENTS
I
11.1.1
(Addition) The Purchaser will specify which, if any, requirements of this Section shall be applied.
THIS INFORMATION FOR AUTHORIZED COMPANY USE ONLY
EXXON RESEARCH AND ENGINEERING COMPANY — FLORHAM PARK, N.J.
IP 6-4-1
Air-Cooled Heat Exchangers
Page 6 of 6
Rev. 0
March 1998
(This practice is appropriate for attachment to Inquiry or Purchase Document)
INTERNATIONAL
PRACTICE
TABLE 3
PHYSICAL DATA
1.
HEADER
a)
b)
c)
d)
3.
Tube bundle (psig): ____ @ F ____
2)
heat treatment: ________
Headers (and cover plate)
3)
radiographed: ________
Header plugs
4)
joint efficiency: ________
Nozzles
HEADER TOP & BOTTOM PLATES
Flanges
1)
thickness (in.): ____ (1)
Bolting
2)
actual corrosion allowance (in.): ____
Tubes
MATERIAL SPECIFICATIONS
Fins
HEADER COVER PLATE
4.
1)
thickness (in.): ____ (1)
2)
actual corrosion allowance (in.): ____
MATERIAL IMPACT REQUIREMENTS
Impact Requirements
(each component) _____ ft lb @ _____F
HEADER TUBE SHEET AND/OR PLUG SHEET
5.
IDENTIFICATION
1)
thickness (in.): ____ (1)
2)
actual corrosion allowance (in.): ____
a)
Purchaser's order no.
ligament efficiency: ______
b)
Purchaser's req. no.
c)
Project Name
d)
Location & Plant
e)
Equipment identification no.
HEADER END PLATES
2)
g)
a)
design pressure and temp: ____ (psig) at ____F
1)
f)
HYDROSTATIC TEST PRESSURE
1)
3)
e)
2.
DESIGN CONDITIONS
thickness (in.): ____ (1)
actual corrosion allowance (in.): ____
MAX. ALLOWABLE STRESS AT DESIGN TEMP.
1)
header (psi): ______
2)
header cover plate (psi): ______
3)
header tube sheet (psi): ______
MAX. ALLOWABLE WORKING PRESSURE
1)
new, at design temp (psig): ____, limited by ____
2)
new & cold (psig): ____, limited by ____
Note:
(1)
Calculated design thickness
General Note
For data reporting in SI units: Linear dimensions in mm, Stress Values in MPa, Fluid Pressure in kPa, Energy
Values in J, Linear Velocity in m/s, Temperatures in C.
Revision Memo
9/68
6/69
1/70
1/71
6/72
Original Issue of Basic Practice
Revision 1
Revision 2
Revision 3
Revision 4
1/74
1/78
6/80
1/85
12/92
Revision 5
Revision 6
Revision 7
Revision 8
Revision 9
3/98
Revision 0 - Original Issue of International Practice
Note: A complete renumbering of IP 6-4-1 was done to agree with the numbering in the latest API 661 Standard.
Deletions/major modifications because the material is sufficiently covered in API-661 or ASME: 4.1.1.11, 4.2.8.1.2, 4.3.3.2a and d,
4.3.5.2, 4.3.5.5.1, 7.2.2, 7.3.1.
Deletions/major modifications because the material is covered by another IP: 1.2.3, 4.1.9.12, 6.2.3, 7.2.14a, b, d, 7.2.23.
Deletions/major modifications based on IP Rationalization reduction criteria: 2.2.10, 3.1.1p, 3.3, 3.3.1.0, 3.3.2, 4.1.5.5, 4.1.6.2.3,
4.1.6.2.12, 4.1.9.13, 4.1.9.14, 4.3.2.2, 4.3.5.1, 4.3.5.4, Table 4.
 Exxon Research and Engineering Company, 1992, 1998
THIS INFORMATION FOR AUTHORIZED COMPANY USE ONLY
EXXON RESEARCH AND ENGINEERING COMPANY — FLORHAM PARK, N.J.