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An update on U.S. valve-related standards

An update on U.S. valve-related standards
Issue Time:2017-09-05

It takes much time and effort by many people to upgrade existing codes and standards, or to develop new ones. The process begins when a parent standards organization (see below) forms a task group to work and prepare an initial draft or investigate proposed changes to an existing document.

This preparation or revision process is complicated in itself, but then there is the approval process, which is especially cumbersome when a draft is balloted and many comments or negatives are received. These comments and negatives must be addressed before a new (revised) draft is prepared. The whole procedure may repeat itself many times until a final is finally approved by the applicable committee membership.

There are also substantial resources involved in producing or revising a valve standard. Individual volunteers lose time from daily work and spend money on travel. The organizations involved have substantial overhead costs in getting the standard reviewed, addressing comments and going through the voting procedure.

Still, because industrial and public safety are paramount, most industry professionals feel the cost and efforts to resolve negatives is necessary to ensure that the standard is useful for the industry.

Here is a summary of what’s happening that valve professionals are monitoring.

CURRENT CHANGES UNDER WAY

AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME)

17 sum standards 2ASME is working on several issues including:

ASME B16: The ASME B16 Standards Committee is under the ASME Board for Pressure Technology Codes and Standards. Seven subcommittees with balanced memberships are responsible for about 34 standards. The published standards are ANSI accredited.

A new B16 Technical Committee on pressure and temperature (P/T) ratings has been established to provide ratings needed for all ASME standards.

ASME B16.34 (2016) Valves: An addition was published in 2016 in which the scope extension of flanged and weld-end valve sizes was changed from nominal pipe size (NPS) 24 to NPS 60 to match B16.47 flanges.

Paragraph 6.1.2 was balloted and approved for the next edition. The proposal was to revise 6.1.2c and delete sub clauses (1) and (2), which were revised in 2009. This caused some manufacturers of three-piece ball valves to substantially increase the wall thickness of the center body, resulting in additional weight of larger valves. Extensive discussions led to a compromise to offer both options—to use the old or the new methods to calculate wall thickness. A major review of needed material and P/T ratings corrections was conducted and will be included in the new edition. All the tables had to be revised to comply with the new titles and numbers for the materials.

A case to use increased ceiling pressures for creep-strength enhanced ferritic materials (F91, F92 and C12A) was approved. This can be used to increase the P/T ratings.

One of the problems with B16.34 was that it took a long time to add a new material. Because of this, a case was developed and approved to add materials not currently listed in Table 1 of B16.34. This is more of an approval procedure than a case and must be supplemented with actual material strength data. It requires approval by B16 SC-N.

The new edition allows the use of ASTM Editions, other than those referenced in the B16 standard, with stated guidance and conformance. Additionally, International Organization for Standardization and MSS [Manufactured Standardization Society, see below] documents are referenced as guidance for construction of cryogenic bonnet extensions. The Subcommittee N continues to develop a similar standard for plastic valves, although progress is very slow because there are no P/T ratings for many of the plastic valves.

B16.10 (2016) Face to Face, End to End: A new edition of this was published in 2016. Major changes and additions include:

Sizes are extended to NPS 60 and new face-to-face dimensions including API 6D, AWWA [American Water Works Association] and MSS Standard Practice (SP)-135. Knife gate valve dimensions were adopted. These changes and additions were major revisions to B16.10.

ASME B16.5 (2016) and B16.47 (2016), Pipe Flanges: New editions were published in 2016. NPS 22 was added to complete the sizes range in B16.5, and P/T tables were reviewed to correct discrepancies.

B16.11 (2016), Forged Fittings: A new edition was published in 2016 that restricted production to disallow non-cylindrical fittings to be made directly from bar. This edition also added coverage for “branch outlet fittings” other than couplings.

16.24 (2016), Cast Copper Alloy Pipe Flanges and Flanged Fittings, and Valves: A new edition was published in 2016 and the title was changed to include “Valves” because it now covers cast copper alloy valves. The scope was incorporated to include C95200 and C95400 copper alloy valve construction data and P/T tables were developed.

ASME B 16.25 (2012), Buttwelding Ends: The next edition will be published in 2017. It will include the addition of NPS 1/2–2 and NPS 50–60 in Table 1. There were some incorrect dimensions in Figure 1. The dimension described at tnom in the figure is not shown correctly in the original so the symbol was eliminated and the requirements were clarified. Also, a ballot was approved to revise Figure 1 to add B36.19 SS piping BW end geometries.

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