Pipe Support Criteria for ASME B31.3 Metallic Piping

June 2002

Process Industry Practices Piping

PIP PNC00001 Pipe Support Criteria for ASME B31.3 Metallic Piping

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 This Practice will be revised, reaffirmed, or withdrawn.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.

Not printed with State funds

June 2002

Process Industry Practices Piping

PIP PNC00001 Pipe Support Criteria for ASME B31.3 Metallic Piping 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

3. Definitions .................................... 3 4. General ......................................... 3 5. Design Requirements .................. 3 5.1 Pipe Support Welded Attachment (Excluding Trunnions)........................ 3 5.2 Pipe Support Clamped Attachment ... 4 5.3 Pipe Support Trunnions..................... 4 5.4 Insulated Piping ................................. 4 5.5 Support for Load-Sensitive Equipment Nozzle ............................. 4 5.6 Pipe Support Brackets for Vertical Vessels .............................................. 5 5.7 Supports for Valve Operator.............. 5 5.8 Supports for Relief Valve Piping........ 5

Process Industry Practices

5.9 Supports for Slug Flow ...................... 5 5.10 Supports for Reciprocating Compressor and Pump Piping .......... 5 5.11 Support Requirements for Piping Systems Subject to AcousticallyInduced Vibration............................... 6 5.12 Pipe Supports for Large OD Pipe (Greater than NPS 24) ...................... 6 5.13 Corrosion Protection.......................... 6 5.14 Hydrostatic Test Condition ................ 7

6. Pipe Support Selection Guidelines................................... 7 6.1 Shoes................................................. 7 6.2 Guides, Stops, and Anchors.............. 7 6.3 Rod Hangers ..................................... 7 6.4 Brackets and Structural Supports...... 8 6.5 Base Supports ................................... 8 6.6 Spring Supports................................. 8 6.7 Sway Braces...................................... 8 6.8 Sway Struts ....................................... 8 6.9 Hydraulic or Mechanical Snubbers ... 8 6.10 Slide Plates........................................ 9

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PIP PNC00001 Pipe Support Criteria for ASME B31.3 Metallic Piping Systems

1.

June 2002

Introduction 1.1

Purpose This Practice outlines the minimum basic criteria for supporting aboveground metallic piping systems in accordance with ASME B31.3 (henceforth referred to as the Code).

1.2

Scope This Practice provides the governing criteria of the design and selection of pipe supports for aboveground piping systems. Project requirements shall identify the extent of design, selections, and shop and field fabrication of pipe supports by the contractor.

2.

References Applicable requirements in the following Practices and industry codes and standards shall be considered an integral part of this Practice. The latest edition and addenda of the following references in effect on the date of contract award shall be the governing document, unless otherwise noted. Short titles will be used herein when appropriate. 2.1

Process Industry Practices (PIP) – PIP PNC00004 – Piping Flexibility Analysis – PIP PNFS0001 – Miscellaneous Pipe Support Details (Working) – PIP STS05120 – Fabrication of Structural and Miscellaneous Steel Specification

2.2

Industry Codes and Standards • American Society of Mechanical Engineers (ASME) – ASME B31.3 – Process Piping • American Society for Testing and Materials (ASTM) – ASTM A123 – Zinc (Hot-Dip Galvanized) Coating on Iron and Steel Products – ASTM A325 – High Strength Bolts for Structural Steel • American Welding Society (AWS) – AWS D1.1 – Structural Welding Code – Steel • Manufacturers Standardization Society (MSS) – MSS SP-58 – Pipe Hangers and Supports – Material, Design and Manufacturer

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June 2002

3.

Definitions Code: As defined in Subsection 1.1 of this Practice contractor: The responsible party for performing engineering and detail design of the piping systems designer: The responsible professional in charge of the engineering and detail design of the piping support systems owner: The party that awards the contract. The owner may be the owner or owner’s authorized agent.

4.

5.

General 4.1

Supports for piping systems shall conform to the requirements of the Code and PIP PNC00004.

4.2

Unless otherwise specified by the owner, pipe supports, guides, anchors, and attachments details shall be provided by the contractor and submitted to the owner for approval. These details shall be per PIP PNSF0001.

4.3

The design of miscellaneous pipe supports shall address expansion and contraction forces and movements in piping.

4.4

The effect of frictional resistance to thermal movement of the pipe shall be considered in the design of piping systems and in the design of supports.

4.5

Pipe support design shall conform to the requirements of MSS SP-58.

4.6

Structural steel for support design shall conform to the requirements of PIP STS05120.

4.7

Welded joints for pipe supports shall conform to the requirements of AWS D1.1.

Design Requirements 5.1

Pipe Support Welded Attachment (Excluding Trunnions) 5.1.1

Pipe attachment welds shall conform to the Code.

5.1.2

For carbon steel and ferrous pipe materials through 9% chrome operating between -20°F (-29ºC) and 500°F (260ºC), pipe support attachment material shall be carbon steel. For carbon steel and ferrous pipe material through 9% chrome operating above 501ºF (261ºC), pipe support attachment material shall be the same as the supported pipe.

5.1.3

For other pipe material, pipe support attachment material shall be the same as the supported pipe.

5.1.4

When required, wear pad minimum dimensions shall be 16-inches (406-mm) long by 1/4 pipe circumference. The thickness shall be 1/4 inch (6 mm) for sizes up to and including NPS 24, and 3/8 inch (10 mm) for larger sizes.


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5.2

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Pipe Support Clamped Attachment Clamp material shall be in accordance with the following table: Pipe Material Temperature -20ºF to 500ºF (-29ºC to 260ºC) 501ºF to 750ºF (261ºC to 399ºC) >750ºF (> 399ºC)

5.2.2

Carbon Steel/ Chrome-Moly Galvanized CS Galvanized or Coated CS Compatible Material Suitable for Temp.

Stainless Steel

Other Alloys

Galvanized or Coated CS SS or Coated CS (See 5.2.2)

Galvanized or Coated CS

SS

Coated CS Compatible Material Suitable for Temp.

Galvanized clamps may be used with stainless steel piping between 501ºF (260ºC) and 750°F (399ºC) provided a thin-gauge (28-gauge minimum) stainless steel isolation shield is inserted between the clamp and the pipe.

Pipe Support Trunnions

5.4

5.5

5.3.1

Unless otherwise specified by the owner, materials for trunnions, reinforcing pads, and gussets shall be the same nominal composition as the supported pipe.

5.3.2

Reinforcing pads shall not be used at elbows, unless otherwise specified by the designer.

5.3.3

Adjustable base trunnions may be used to accommodate differences in elevation or field tolerances.

Insulated Piping 5.4.1

Supports for insulated piping shall be such that insulation will not be damaged at the point of support because of pipe movement.

5.4.2

Supports for cold-insulated pipe shall be supported around the insulation to avoid cold bridges and protrusions through the vapor barrier.

5.4.3

Supports for piping insulated for cold conservation or anti-sweat shall be designed to prevent the formation of condensation. The support shall be designed so that the insulation will not be crushed.

5.4.4

Supports for insulated piping shall be designed for thermal plus acoustic insulation thickness.

5.4.5

Trunnions on cold-insulated piping shall be insulated for a length equal to T+3t, where T is the insulation thickness of the line and t is the insulation thickness of the trunnion. Thereafter, the trunnion shall have a minimum uninsulated length of 6 inches (150 mm). If the trunnion length does not meet this requirement, either the entire trunnion shall be covered with cold insulation or a cold-insulated support shall be used.

Support for Load-Sensitive Equipment Nozzle For piping connected to load-sensitive equipment, the support system shall be designed to minimize the weight and weight moment on the equipment nozzle.

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5.6

5.7

Pipe Support Brackets for Vertical Vessels 5.6.1

The pipe support bracket shall be located as close to the nozzle as practically possible.

5.6.2

Support for overhead lines may need to be designed for hydrostatic test conditions.

5.6.3

The spacing of vessel piping guides shall be based on the maximum allowable piping span as determined by the designer in accordance with PIP PNC00004.

5.6.4

When pipe is installed while the vessel is in the horizontal position (dress-out); the vessel attachments, piping support, and guide brackets shall be designed for this temporary horizontal position.

Supports for Valve Operator Valves and valve operators shall be evaluated and supports shall be provided as required.

5.8

Supports for Relief Valve Piping Reaction force of safety relief devices shall be evaluated and supports shall be provided as required.

5.9

Supports for Slug Flow Reaction forces acting at changes in direction due to slug flow shall be evaluated, and supports shall be provided as required.

5.10

Supports for Reciprocating Compressor and Pump Piping 5.10.1 All lines subject to vibration resulting due to pulsation of reciprocating compressor or pump shall be restrained in directions perpendicular to the longitudinal axis of the pipe, whether an acoustic study has been performed or not. Either clamp-type supports allowing only axial movement or holddown-type supports allowing both axial and lateral movements shall be used. Coupling moments created by the clamps shall be evaluated by the designer. 5.10.2 Pipe supports shall preferably be supported on concrete. 5.10.3 The maximum unsupported spans of lines subject to the effects of vibration shall be evaluated by the designer. 5.10.4 All supports shall be designed for the various dynamic loads imposed by the vibrating lines.


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June 2002

5.10.5 Adjustable wedge-type supports for volume bottles located directly under the compressor cylinders shall be used. These supports shall be designed to allow final support adjustment when a full operating temperature has been reached. 5.10.6 Cinch anchors shall not be used for supports that are anchoring or restraining vibrating lines. 5.10.7 Vibrating lines should have independent support structures if it is feasible. 5.11

Support Requirements for Piping Systems Subject to AcousticallyInduced Vibration When a piping system is identified for an acoustically-induced vibration, the piping system and the supports shall be designed for the effects of vibration and fatigue. The use of bolted-on supports, supports with full circumferential bands, or stiffening rings should be considered.

5.12

Pipe Supports for Large OD Pipe (Greater than NPS 24) 5.12.1 Saddle reinforcement or wear pads shall be used at the point of support bearing to handle the weight load and to protect abrasion. 5.12.2 The maximum allowable span for various pipe diameters and wall thicknesses shall be developed by the designer. 5.12.3 Wear pads shall be constructed of equal or higher grade material than the supported pipe. 5.12.4 When possible, pipe shoes may be used in place of wear pads. 5.12.5 The pad bearing surface shall be a minimum of 4 inches (100 mm) in length.

5.13

Corrosion Protection 5.13.1 Stainless steel and copper pipe support components do not require any surface coating, unless otherwise specified. 5.13.2 Spring coils shall be coated per manufacturer’s standards, unless otherwise specified. 5.13.3 All support steel connecting to the structures shall be galvanized, unless otherwise specified. 5.13.4 All pipe supports (i.e., lugs, shoes, trunnions, etc.) welded to pipe spools shall be prepared and coated the same as the supported pipe. 5.13.5 Unless otherwise specified by the owner, all support elements in the following list shall be hot-dip galvanized:

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•

eye nuts

•

turn buckles

•

beam attachments

•

adjustable base supports

•

spring housings



June 2002

•

load flanges

•

threaded rods

•

bolts and nuts

5.13.6 Galvanized coating shall conform to the requirements of ASTM A123 with the following exceptions: a. The weight of zinc coating shall not average less than 2.25 oz/ft2 (0.7 kg/m2). b. No individual specimen shall show less than 2.0 oz/ft2 (0.6 kg/m2) of zinc coating. 5.14

Hydrostatic Test Condition When temporary supports for hydrostatic testing are not used, permanent supports shall be designed for a hydrostatic test case.

6.

Pipe Support Selection Guidelines 6.1

6.2

6.3

Shoes 6.1.1

Shoes are required on insulated piping to prevent damage to the pipe insulation and to provide a sliding surface for pipe movement.

6.1.2

Clamp-on-type shoes shall be used where welding to the pipe is not allowed or is impractical (e.g., in piping with internal lining, galvanized piping, piping requiring post-weld heat treatment, etc).

Guides, Stops, and Anchors 6.2.1

Pipe support guides, stops, and anchors are used to control movement of the piping to meet stress and flexibility requirements, to provide restraint against static, transient, and dynamic forces; to prevent excessive pipe movement; and to provide stability to the piping geometry.

6.2.2

The anchor and guide system on piping with unrestrained expansion joints shall be designed in accordance with the Code.

6.2.3

When more than one piping system is anchored or guided on a common structure, the structure must be designed for the most severe combination of the loads.

Rod Hangers 6.3.1

Rod hangers may be used when support underneath the pipe is impractical. In general, the use of rod hangers should be minimized.

6.3.2

The design shall ensure that rod hangers are not subject to movements exceeding 4 degrees of swing.


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6.4

6.5

6.6

6.7

June 2002

Brackets and Structural Supports 6.4.1

When attaching brackets to fireproofed steel, the fireproofing shall be removed and replaced. Brackets shall not be attached to the fireproofing.

6.4.2

Support brackets shall not be attached to ladders, handrails, and other nonload-carrying structures.

Base Supports 6.5.1

Base supports are used when piping is positioned close to grade level or platforms. Typical types of base supports are trunnions and stanchions.

6.5.2

The designer shall determine criteria for installing base supports directly onto paving. If the paving load is exceeded, an independent foundation shall be provided.

6.5.3

Base supports may be supported directly onto platform grating. The designer shall determine criteria for support directly onto the grating.

Spring Supports 6.6.1

Spring supports are used to support piping while allowing vertical thermal movements. Spring supports shall be individually sized and selected.

6.6.2

All spring design data shall be submitted to the owner.

6.6.3

Variable spring supports may be used when the variation between the installed load and the operating load is 25% or less. Constant spring supports shall be used when the variability exceeds 25%.

6.6.4

Constant spring supports may be used when there are large vertical movements, when the limits of the variable spring are exceeded or become impractical, or when it is necessary to avoid transferring load spring reaction to critical terminals or equipment.

6.6.5

Selection of spring hangers shall also follow the requirements in Section 6.3.1 and Section 6.3.2 of this Practice.

Sway Braces Sway braces may be used to control vibration, absorb shock-loading, restrain the thermal movement, or brace a piping system against sway. Sway braces shall not be used for lines connected to reciprocating compressors or pumps.

6.8

Sway Struts Sway struts may be used to control directional movement of piping due to thermal expansion or contraction.

6.9

Hydraulic or Mechanical Snubbers Hydraulic or mechanical snubbers shall be used to design a piping system for impulse or shock-loading due to earthquake, flow transients, or wind gusts; and when gradual thermal movement must be allowed.

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6.10

Slide Plates Slide plates are used to reduce frictional forces resulting from pipe movements. The top surface shall be larger than the bottom surface to prevent the accumulation of trash on the sliding surfaces.


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Pipe Support Criteria for ASME B31.3 Metallic Piping

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