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Valve flange thickness vs pipe flange thickness

Valve flange thickness vs pipe flange thickness

(OP)
For an example, let's use a 3" 150 pound slip-on pipe flange. According to ASME B16.5, it must be .88" thickness (tF). However, I've noticed ASME B16.34 valves bolted to these flanges that are substantially thinner, approximately .750"-.780".

According to ASME B16.34, 6.2.2 Flanged Ends. "Flanged ends shall be prepared with flange facing, nut-bearing surfaces, outside diameter, thickness, and drilling in accordance with ASME B16.5 or ASME B16.47, Series A or Series B requirements for (a) flanged fittings for Class 150 and 300 valves (b) flanges for Class 600 and higher valves."

So why are brand new ASME B16.34 valves allowed to have thinner flanges than the ASME B16.5 pipe flanges they are bolted to?

RE: Valve flange thickness vs pipe flange thickness

If you actually read the code properly, it refers you to notes 2-4.


note 2 refers you to table II-9 for flanges cast as part of fittings which for sizes <3 1/2" can be thinner.

The dimension Tf for a 3" class 150 (pound is not the correct term) ASME flange for a fitting can be min 0.69"

4" and above its the same min thickness.

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RE: Valve flange thickness vs pipe flange thickness

(OP)
Thank you for that response. Very helpful.

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