ASME B31.3-2020: Process Piping Code Changes

Yellow process piping that follows the ASME B31.3-2020 code offshore.

Process piping transports fluids in a range of locations—most notably, petroleum refineries, onshore and offshore petroleum and natural gas production facilities, food and beverage processing facilities, and chemical, pharmaceutical, textile, paper, ore processing, semiconductor, and cryogenic plants. Due to this ubiquity, ASME B31.3-2020: Process Piping applies to systems that transport chemicals, petroleum products, fluidized solids, refrigerants, cryogenic fluids, and gas, steam, air, and water.

What is ASME B31.3?

ASME B31.3-2020 is part three of the overarching ASME B31 Code for Pressure Piping. While being a Code Section and typically referred to as a Code, ASME B31.3-2020 is also an American National Standard. It prescribes guidelines for materials and components, design, fabrication, assembly, erection, examination, allowable stress, acceptance criteria, and testing of process piping to aid numerous groups. This includes the owner of the piping installation, as well as the designer, owner’s inspector, and manufacturer, fabricator, and erector.

ASME B31.3-2020: Changes from the 2018 Edition

ASME B31.3-2020 revises the 2018 edition of the same standard for process piping. Some changes made to the latest edition of the standard include:

  • The introduction of the overarching ASME B31 Code was expanded to specify that the standards encompass requirements for examination, inspection, and testing of piping.
  • New section added specifying the units of measure are stated in both SI and US Customary units in the Code text.
  • Requirements for ratings at the junction of different services were clarified.
  • The limits of calculated stress due to occasional loads (e.g. those from winds and earthquakes) have been clarified in relation to the sum of stresses sustained.
  • Information on flexibility and stress intensification factors has been expanded.
  • Table 326.1, “Component Standards,” was revised in its entirety.
  • For preheating rules, it is noted that the ASME B31P may be used as an alternate option.
  • Requirements have been significantly expanded for supports for thermoplastic, reinforced thermosetting resins (RTR), and reinforced plastic mortars (RPM) piping.
  • Fluid service requirements for valves and specialty components were expanded to address listed valves, unlisted valves, bonnet bolting, and stem retention.
  • The scope for Chapter IX, “High Pressure Piping,” was revised in its entirety.
  • The section on lower temperature limits for listed materials was revised in its entirety.
  • The section on welding responsibility was significantly expanded to clarify the employer’s responsibility for the welding performed and conducting qualification tests.
  • End preparations were added.
  • Appendix D, “Flexibility and Stress Intensification Factors,” from the 2018 edition of the standard was deleted.
  • Appendix E, “Reference Standards,” was revised in its entirety.
  • Design criteria has been added to Appendix F, “Guidance and Precautionary Considerations.”
  • The bonding of plastics has been added to Appendix F.

Users should note that only a portion of the changes to ASME B31.3-2020 are included in the list above. All changes made to this American National Standard are listed just after the introduction in the document, where the location of each alteration is laid out. Furthermore, the ASME B31.3-2020 document clearly notes wherever a revision has taken place by a margin note, (20).

For further compliance, users might be interested in the ASME B31 Piping Package or Power and Process Piping Package, which bundle several related standards at a discount.

ASME B31.3-2020: Process Piping is available on the ANSI Webstore.

ASME B31.3-2018: Changes from the 2016 Edition

Past revisions of ASME B31.3 have also been expansive, so we’ve listed some key changes made to the previous revision of the code released in 2018:

  • Text was added to “General Statements” in Chapter 1, “Scope and Definitions,” to note that the owner of a piping installation can designate a representative to carry out selected responsibilities of ASME B31.3-2018, but “the owner retains ultimate responsibility for the actions of the representative.”
  • The standard clarifies that it was developed considering piping found in processing plants and terminals across numerous industries.
  • Definitions were added for owner, readily accessible (for visual examination), and representative.
  • External vortex shedding and acoustically induced vibration were added as sources of impact for vibration that the piping is to be designed, arranged, and supported to eliminate.
  • Rules for the use of piping components not listed in Table 326.1, “Component Standards,” were altered.
  • Weld joint strength reduction factor, W, was included as an allowance for pressure and temperature variations.
  • A new row for Carbon Steel was added in Table 302.3.5, “Weld Joint Strength Reduction Factor, W.”
  • In section 311.2, which covers “specific requirements” for welded joints, paragraphs on welds for category D fluid service, severe cyclic conditions, and elevated temperature fluid performance were removed.
  • Table 314.2.1, which previously was previously the “Minimum Thickness of External Threaded Components,” is now the “Minimum Schedule of Components With External Threads.”
  • ASME B18.31.2 was listed under Table 361.1, “Component Standards,” as the standard for “Continuous Thread Stud, Double-End Stud, and Flange Bolting Stud (Stud Bolt) (Inch Series).”
  • The scope of Chapter IX, “High Pressure Piping,” was revised in its entirety.
  • Text on fatigue analysis for unlisted high pressure piping components was added.
  • Note that the use of the word “pipe” does not include “tube” or “tubing” in section K314 on “Threaded Pipe Joints.”
  • Guidelines regarding flared end tubing joints were added to K315, “Tubing Joints.”
  • Section K320, “Analysis of Sustained Loads,” was added.
  • Section K326.4, “Repair of Piping Components By Welding,” was updated to highlight the importance of the owner’s approval.
  • Table C-6M, “Moduli of Elasticity for Metals (SI Units),” was added.
  • Examples of rounding for piping that has been placed in service were added as new section F300.1.4.
  • General statements were added in Appendix F, “Guidance and Precautionary Considerations.”
  • Appendix W, “High-Cycle Fatigue Assessment of Piping Systems,” was added.
  • Appendix Z, “Preparation of Technical Inquiries,” was revised in its entirety.

ASME B31.3-2016: Changes from the 2014 Code

For those users who have followed ASME B31.3 for its past few revisions, we’ve also included some major changes made to the 2016 code here:

  • Guidance was added on severe cyclic conditions, or “Conditions applying to specific piping components or joints for which the owner or the designer determines that construction to better resist fatigue loading is warranted.”
  • Either MPa (megapascal) or ksi (kilopound per square inch) units became allowed for compliance with the Code.
  • A new section was added for expansion joints.
  • The consideration of assembly requirements for bolted flanged joints and flanged joint assembly qualifications was added in the engineering design.
  • Ultrasonic examination acceptance criteria was added.
  • The definition for Category M Fluid service was revised.
  • Threaded joints and tubing joints no longer needed to be leak tested in accordance with the ASME B31.3 leak test.
  • Vacuum leak testing was included as an alternative to the internal pressure method.
  • The Code now allowed some joints to be covered by insulation during leak testing.
  • Pipe and related components and assemblies became allowed to be tested either separately or as assembled piping.
3 thoughts on “ASME B31.3-2020: Process Piping Code Changes
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