REAFFIRMATION
October 2002
Process Industry Practices
Process Control
PIP PCCIP001
Instrument Piping and Tubing Systems Criteria
PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES
In an effort to minimize the cost of process industry facilities, this Practice has
been prepared from the technical requirements in the existing standards of major
industrial users, contractors, or standards organizations. By harmonizing these technical
requirements into a single set of Practices, administrative, application, and engineering
costs to both the purchaser and the manufacturer should be reduced. While this Practice
is expected to incorporate the majority of requirements of most users, individual
applications may involve requirements that will be appended to and take precedence
over this Practice. Determinations concerning fitness for purpose and particular matters
or application of the Practice to particular project or engineering situations should not
be made solely on information contained in these materials. The use of trade names
from time to time should not be viewed as an expression of preference but rather
recognized as normal usage in the trade. Other brands having the same specifications
are equally correct and may be substituted for those named. All Practices or guidelines
are intended to be consistent with applicable laws and regulations including OSHA
requirements. To the extent these Practices or guidelines should conflict with OSHA or
other applicable laws or regulations, such laws or regulations must be followed.
Consult an appropriate professional before applying or acting on any material
contained in or suggested by the Practice.
This Practice is subject to revision at any time by the responsible Function Team and will
be reviewed every 5 years. This Practice will be revised, reaffirmed, or withdrawn.
Information on whether this Practice has been revised may be found at www.pip.org.
© Process Industry Practices (PIP), Construction Industry Institute, The
University of Texas at Austin, 3925 West Braker Lane (R4500), Austin,
Texas 78759. PIP member companies and subscribers may copy this Practice
for their internal use. Changes, overlays, addenda, or modifications of any
kind are not permitted within any PIP Practice without the express written
authorization of PIP.
PIP will not consider requests for interpretations (inquiries) for this Practice.
PRINTING HISTORY
Issued
Reaffirmation
Not printed with State funds
July 1998
October 2002
REAFFIRMATION
October 2002
Process Industry Practices
Process Control
PIP PCCIP001
Instrument Piping and Tubing Systems Criteria
Table of Contents
1. Introduction .................................. 2
1.1 Purpose ............................................. 2
1.2 Scope................................................. 2
2. References.................................... 2
2.1 Process Industry Practices................ 2
2.2 Industry Codes and Standards.......... 2
5. Process Instrument Tubing
and Piping................................... 5
5.1
5.2
5.3
5.4
Process Piping Connections ............. 5
Instrument Piping............................... 5
Instrument Tubing.............................. 5
Traced and Insulated Tube
Bundles.............................................. 6
3. General ......................................... 2
3.1
3.2
3.3
3.4
Routing .............................................. 2
Supports ............................................ 3
Tubing Installation ............................. 3
Threaded Pipe Connections.............. 4
4. Instrument Air Piping
and Tubing .................................. 4
4.1 General .............................................. 4
4.2 Installation, Routing,
and Connections................................ 4
4.3 Tubing................................................ 4
Process Industry Practices
Page 1 of 6
REAFFIRMATION
PIP PCCIP001
Instrument Piping and Tubing Systems Criteria
1.
October 2002
Introduction
1.1
Purpose
This Practice provides to designers and installers general requirements for the design
and installation of instrument piping and tubing systems.
1.2
Scope
This Practice specifies the general requirements for the design and installation of
instrument piping and tubing. This Practice does not cover piping and tubing material
specifications or installation details for instruments and analyzers. These are
addressed in other Process Industry Practices (PIP) documents.
2.
References
2.1
Process Industry Practices (PIP)
– PIP PCCIA001 – Instrument Air Systems Criteria
– PIP PCSIP001 – Instrument Piping and Tubing Systems Specifications
– PIP PNSM0002 – Piping Material Specifications – Line Class Index
2.2
Industry Codes and Standards
• American Society of Mechanical Engineers (ASME)
– ASME B1.20.1 – Pipe Threads, General Purpose (Inch)
• ISA, The International Society for Measurement and Control (ISA)
– ISA RP 42.1 – Nomenclature for Instrument Tube Fittings
3.
General
3.1
Routing
3.1.1
No process or service medium, except air, shall be connected into or routed
through control rooms, instrument or electrical control buildings, or enclosed
field panels.
Comment: Sample systems and process analyzers that require a shelter or
enclosure are an exception, provided that the requirements for appropriate
electrical area classifications are followed.
Page 2 of 6
3.1.2
Tubes and tube bundles that handle process fluids shall not be installed in
channel or cable trays that contain electrical cabling.
3.1.3
Tubing shall not be routed along or supported from handrails.
3.1.4
Tubing shall be installed in a manner that allows for calibration of
instruments and removal of adjacent instruments, equipment, and tubing.
Process Industry Practices
REAFFIRMATION
PIP PCCIP001
Instrument Piping and Tubing Systems Criteria
October 2002
3.2
Supports
3.2.1
All tubing shall be supported to avoid vibration, sags, and vapor/liquid traps.
Comment: Tubing supports should be spaced not more than four feet
apart.
Comment: In locations where mechanical damage is likely, tubing may be
installed in structural channel, angle, or in trays, even though not required
for normal support.
Comment: Tubing should be supported on walls or structural steel
whenever possible.
3.2.2
When tube bundles or preinsulated/traced tubing are used, the manufacturer's
recommendations for bend radius, support methods, spacing and thermal
expansion allowances shall be used as the basis for design and installation.
3.2.3
Tubes and tube bundles and their support channels and trays shall not be
supported from process or utility piping. Tubing channels or trays shall not
be supported by bolting to transmitter brackets or control valves.
Comment: Tubing may be supported from structural members and
instrument stands.
3.2.4
Stainless steel straps or clamps shall be used to attach bare metal tubing to
structural angle, channel and cable trays. Tube bundles shall be secured with
metal straps and clamps or plastic tie-down straps. Plastic tie-down straps
shall be ultraviolet resistant and of a suitable material for the ambient
conditions.
Comment: Tubing installed in raceways shall be firmly attached to the
support at intervals not exceeding 10 feet.
3.3
3.2.5
All instrument piping and tubing to equipment or process piping shall be
properly supported to avoid strain on equipment, piping connections, and
instruments. Thermal expansion and vibration of the process piping or
equipment to which an instrument is connected shall be considered in
designing and installing the supports.
3.2.6
Materials of construction for instrument piping supports shall be appropriate
for the ambient conditions and shall be consistent with the materials used for
other piping supports in the facility.
Tubing Installation
3.3.1
All tubing shall be installed in a neat manner with no signs of crimping,
flattening, or bends with radius too small. Tubing shall not be marked or
scored.
3.3.2
Tube-bending tools shall be used to form tubes. The minimum bend radius
shall be in accordance with directions and recommendations of tube-bender
manufacturer. Hand bending of tubes without the use of tube-bending tools is
not permitted.
3.3.3
All open tubing shall be capped to keep out dust, dirt, moisture, and other
foreign matter.
Process Industry Practices
Page 3 of 6
REAFFIRMATION
PIP PCCIP001
Instrument Piping and Tubing Systems Criteria
3.4
4.
October 2002
3.3.4
Tube ends shall be cut square and deburred after cutting.
3.3.5
Tubing shall be assembled with the specified compression fittings in
accordance with the manufacturer's instructions. The proper tools,
recommended by the manufacturer, shall be used to assure adequate
engagement and tightness.
3.3.6
Tube fittings (for example, unions and tees) installed in individual or parallel
tube runs shall be staggered and raised to allow tube removal or reinstallation
without distorting or damaging the individual tube or adjacent tubes.
3.3.7
Tubing must have a minimum length of straight run adjacent to bends to
allow correct installation of fittings.
Threaded Pipe Connections
3.4.1
All threaded pipe connections shall be tapered and comply with
ASME B1.20.1.
3.4.2
Sealant/lubricant for threaded instrument piping connections shall meet the
requirements of the process service.
3.4.3
Polyfluorethylene (PTFE) tape shall not be used as a thread lubricant on pipe
threads for pneumatic signal or instrument air pipelines that are downstream
of the filter regulator, except with owner approval.
Instrument Air Piping and Tubing
4.1
General
Instrument air piping and tubing shall conform to the requirements in
PIP PCCIA001. The tubing components shall conform to the specifications for
instrument air tubing in PIP PCSIP001.
4.2
4.3
Installation, Routing, and Connections
4.2.1
Building penetrations for instrument pneumatic piping and tubing shall be
consistent with the building requirements. The intended use and location of
the building may require pressure-tight and flame-retardant penetrations.
4.2.2
Instrument air tubes, tube bundles, and tube trays shall be routed to avoid
excess heat or damaging hot spots. Avoid routing directly above pumps
handling flammable materials, near furnaces, or air-cooled exchangers,
except when routed to final instrument air users.
4.2.3
As a minimum, brass tube fittings shall be used to connect instrument air or
pneumatic signal lines. Plastic tubing fittings or brass fittings with plastic
ferrules shall not be used.
Tubing
4.3.1
Page 4 of 6
Materials for instrument air tubing shall be chosen with full consideration of
requirements for the application, such as external corrosion resistance,
vibration resistance, and fire protection.
Process Industry Practices
REAFFIRMATION
PIP PCCIP001
Instrument Piping and Tubing Systems Criteria
October 2002
4.3.2
For single-instrument air supply tubing, the minimum shall be copper,
3/8-inch outside diameter (OD) x 0.032-inch wall.
4.3.3
For pneumatic signal tubing, the minimum shall be copper 1/4-inch OD x
0.030-inch wall.
4.3.4
Stainless steel tubing shall be used near high-vibration equipment and where
required by process or ambient conditions.
Comment: Polyethylene tubing may be used, with owner approval, in
applications in which it is desirable to have a valve fail to a specific
position based on loss of air from the tube melting in a fire.
Comment: Stainless steel tubing may be used on preassembled equipment,
such as control valves.
5.
Process Instrument Tubing and Piping
5.1
Process Piping Connections
The piping specifications for the process service shall govern the design of the piping
connections for instrumentation from the process pipe or vessel through the primary
block valve (root valve).
5.2
Instrument Piping
From the primary block valve to the instrument, the instrument piping specifications
shall be used. The materials of construction and pressure ratings of all
process-connected instrument piping, fittings, and valves shall be compatible with
and meet or exceed applicable piping specifications for the process service.
5.3
Instrument Tubing
5.3.1
Process Industry Practices
From the primary block valve to the instrument, all process-connected
instrument tubing shall be compatible with applicable piping specifications
for the process service, subject to the minimum requirements listed as
follows:
5.3.2
Instrument process tubing, as a minimum, shall be Type 316 stainless
steel 3/8-inch OD x 0.035-inch wall tubing. Fittings shall be, as a
minimum, Type 316 stainless steel.
5.3.3
Tubing and associated components shall conform to the applicable
specifications in PIP PCSIP001.
Page 5 of 6
REAFFIRMATION
PIP PCCIP001
Instrument Piping and Tubing Systems Criteria
5.4
October 2002
Traced and Insulated Tube Bundles
5.4.1
When heat tracing is required, prefabricated traced and insulated tube
bundles are preferred. When short leads or configuration prevent reasonable
use of these bundles, individual tubes with field-installed tracing and
insulation shall be provided.
5.4.2
Tube Bundle Installation
5.4.2.1 When installing multiple groupings of electric traced tubing bundles,
the manufacturer’s recommendations for separation and spacing shall
be followed. In the absence of the manufacturer’s recommendations,
a minimum of 1/2-inch separation shall be allowed.
5.4.2.2 Support clamps shall have a wide bearing surface with a fixed
drawdown point. Clamps or tie-wrap fasteners that exert point
pressure shall not be used.
Comment: Bends should be kept to a minimum. Tubing should
be bent using a properly sized conduit bender, mandrel, or
sliding shoe cable.
Comment: The minimum allowable bend radius should be per
the manufacturer’s instructions except when tight bends are
necessary. The jacket and insulation may be stripped and the
tubing bent with a tubing bender.
Comment: When tubing fittings are to be installed, the length of
jacket to be stripped is determined by the length of tubing or
tracer required to make connections.
Comment: Jacketing should be cut square.
Comment: The exposed jacket ends shall be sealed with the
manufacturer's end sealant, RTV silicone, or heat-shrinkable
boots.
Comment: Supports should be installed every 4 feet to 6 feet in
the horizontal plane and every 12 feet to 15 feet in the vertical
plane. Tubing should not be supported within a bend as this
limits movement caused by thermal expansion and limit
flexibility. Support clamps should not be installed within
18 inches of any directional change.
Page 6 of 6
Process Industry Practices