ASME B31.3-2018 revises the 2016 edition of the same standard for process piping. Some changes made to the latest edition of the standard include:
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.
Users should note that only a portion of the changes to ASME B31.3-2018 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 B31.3-2018 document clearly notes wherever a revision has taken place by a margin note, (18).
https://blog.ansi.org/2019/08/asme-b31-3-2018-process-piping-changes/
In addition to the many clarifications, updated references to codes and standards, updates to basic allowable stresses, and added listed materials, there are several substantive changes to the 2016 Edition of ASME B31.3, Process Piping, which is scheduled to be issued mid-January 2019. These substantive changes are:
Owner
Added specific permission for the owner to designate a representative to carry out selected responsibilities required by this Code, and noted that the owner retains ultimate responsibility for the actions of the representatives.
Flange Design
Added the ASME B&PV Code Section VIII, Division 2, para. 4.16 flange calculation method as an acceptable way to design flanges for B31.3 applications. The Division 2 procedure considers pressure, gasket seating, and externally applied axial forces and net-section bending moments.
Stress Intensification and Flexibility Factors
Added specific references to ASME B31J-2017 as a resource for stress intensification and flexibility factors as an alternate to Appendix D.
High Cycle Fatigue
Added Appendix W, which describes an alternate method for evaluating high cycle fatigue when specified by the owner. The method in intended to be used when the number of significant stress cycles exceed 100,000.
A significant stress cycle is defined as a cycle with a computed stress range greater than 20.7 MPa (3.0 ksi) for ferritic and austenitic steels. For other materials. or corrosive environments, all cycles shall be considered significant unless otherwise documented in the engineering design. The existing rules provide an acceptable method of evaluating piping systems for fatigue when the number of significant stress cycles is less than or equal to 100,000. The piping cyclic loadings may be due to thermal expansion, anchor motion, vibration, inertial loads, wave motion or other sources.
Heat Treatment for Attachment Welds
Added explicit language requiring heat treatment for structural attachments welded directly to pressure-containing materials when the piping is required to be heat treated.
Visual Examination
Added a definition for readily-accessible: those surfaces that can be examined from not more than 600 mm (24 in.) and at an angle not less than 30 degrees to the surface to be examined.
Increased visual examination required for normal fluid service welds from 5% random to 100%.
High Pressure Piping Fatigue Analysis
A fatigue analysis is required for all piping systems in Chapter IX High Pressure Fluid Service. In previous editions, this analysis was permitted to be performed in accordance with the BPV Code, Section VIII, Division 2 or Division 3. Division 2’s fatigue analysis involves using a standard S/N curve to determine the design fatigue life. Division 3 also allows an S/N curve approach, but only if it can be shown that the piping component will fail in a leak-before-burst mode. Otherwise, a more rigorous fracture mechanics evaluation is required. The Division 3 S/N analysis contains several requirements that are not included in Division 2, such as surface finish and mean stress corrections. Because the Division 2 approach is less precise than the Division 3 approach, wherever possible, Division 2 was eliminated as an option for the required Chapter IX fatigue analysis.
https://becht.com/becht-blog/entry/asme-b31-3-substantive-changes-in-the-2018-edition