ASME B31.3 302.3.2(f) Unlisted Materials confusion 3

[AlaskanME]

I was asked by our maintenance personnel if using a 4" paddle blind made out of A572 Gr. 50 material was okay. Since it is not a B16.48 blind, I was following ASME B31.3 para. 304.5.3 to make sure the thickness was adequate for the required pressure and temperature. Unfortunately, A572 Gr. 50 is not a listed material in Table A-1 so I don't know what to use for allowable stress. The material properties show a tensile strength of 65 ksi and a yield strength of 50 ksi.

I assumed I could multiple the yield strength by 2/3 but that was before I read 302.3.2(f), and I don't understand how to follow it since I don't know the material tensile strength "at temperature" as it states below. If anyone could help clarify this, it would be greatly appreciated.

302.3.2(f):
(f) Unlisted Materials. For a material that conforms to
para. 323.1.2, the tensile (yield) strength at temperature
shall be derived by multiplying the average expected
tensile (yield) strength at temperature by the ratio of
ST (SY) divided by the average expected tensile (yield)
strength at room temperature. I am not sure.

 

[pmover]

see thread292-289794

good luck.

 

[XL83NL]

You want to use a structural steel for a pressure application? ASTM A 572 = Standard Specification for High-Strength Low-Alloy Columbium-Vanadium Structural Steel
If you need to determine allowable stresses at temperature, that may become quite tricky with structural steel product standards. Such standard usually dont provide tensile or yield stresses at temperature.

 

[LittleInch]

Let's get real here - this is a 4" paddle blind we're talking about.

Grade 50 sheet is almost certainly stronger than the "normal" blind material which is probably equal to grade 35.

I assume this is a flat plate sandwiched between two flanges??

If you use the B16.48 thickness you will be OK.

It's a blind therefore the temperature should be ambient if ther eis no flow.

If you're separating high temp fluid from low temp then you might have an issue, but blinds should be a back up to valves, not a replacement.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XL83NL]

Well said LI.

 

[AlaskanME]

Your assumption is correct LI and this one is a backup to a block valve.

Thanks for the replys everyone.