ASME BPVC Section II Part D
ASME BPVC Section II Part D
(OP)
I was reading over the codebook and came across a material (SA-312 TP304L) that has two different allowable stress values. One of them (The higher value) has note G5 attached to it.
G5 says “Use of these stresses may result in dimensional changes due to permanent strain.”
My question is: who in their right mind would use these allowable stress values for a pressure vessel? The note goes on to say that this material is not recommended in flanges because it can cause leaking (that's understandably). Is the risk of permanent dimensional change really worth the reward of a slightly higher allowable stress?
Your thoughts and opinions are greatly appreciated,
Tyler
G5 says “Use of these stresses may result in dimensional changes due to permanent strain.”
My question is: who in their right mind would use these allowable stress values for a pressure vessel? The note goes on to say that this material is not recommended in flanges because it can cause leaking (that's understandably). Is the risk of permanent dimensional change really worth the reward of a slightly higher allowable stress?
Your thoughts and opinions are greatly appreciated,
Tyler





RE: ASME BPVC Section II Part D
Take that a step further, we always specify 304/304L dual certified material, and use the higher of the two allowable stress values for 304 straight grade...
RE: ASME BPVC Section II Part D
RE: ASME BPVC Section II Part D
Regards,
Mike
The problem with sloppy work is that the supply FAR EXCEEDS the demand
RE: ASME BPVC Section II Part D
In order to understand where these allowable stresses come from, it is necessary to understand both the stress-strain response of these austenitic stainless steels as well the role of design margins (against yield and ultimate). The permanent dimensional changes are so small that they are not generally observable.
If that blew your mind - how about Appendix 44?
RE: ASME BPVC Section II Part D
Recently estimated a vessel where difference made a saving of several tenths of thousands in material cost.
If you looked though at the MAWP of the vessel there was still pretty good margin compared to the design pressure.
So it's worth using where allowed.
RE: ASME BPVC Section II Part D
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P.E. Metallurgy, Plymouth Tube
RE: ASME BPVC Section II Part D
@metengr thanks especially for your reply, that was the one to help everything click in my mind.