ASME B16.34 LAST EDITION vs 2004 EDITION

[BFZHA]

Hi,
We have received an offer from one of our supplier for gate valves. He have stated that the valves are offered according to ASME B16.34 last edition except for paragraph 6.1.2 that remains as stated in 2004 edition.

By comparing the two editions, I found differences in tables 3A/3B for valves minimum thicknesses for some diameters and series.

However, the diffrence is not so significant for example for NPS 24" serie 600# :
In edition 2004, min wall thk is 43.2 mm
In edition 2009, min wall thk is 43.3 mm

The difference is 0.1 mm. This difference can be covered by fabrication tolerances.

So, I would like to now:
1- If it is a unique difference between the two editions of ASME B16.34 for this paragraph 6.1.2?

2- If not, what are the other differences?

Thanks.

 

[bcd]

Hello,

The big changed occurred in 2009. Paragraph (c) was added that required many valves of "multi-piece construction" to have thicker walls in the center body section because the "d" was no longer based on the valve port size (just for the center section, not the end pieces). Not sure how this applies to a typical gate valve as the paragraph was primarily focused on 3-piece ball valves. Most gate valves have bolted or pressure seal bonnets and would not fit the intent of this paragraph.

So working with the older revision (2004), the wall thickness of the center section was still the port diameter or 90% of the port diameter. Since then, the internal diameter of the center section determines the wall thickness of that part of the valve.

Since your supplier has his casting patterns and tooling already paid for, and the valves most likely have a history of successful use, the supplier is unwilling to spend more money to get new casting patterns and machining tooling because the committee responsible for maintaining this standard made a change that unintentionally caused a problem for them.

Hope this helps.