Difference between ASME SA187 Gr.5 and ASME SA336 Gr.5

[MchDesign]

Hello All,

Considering the forging ASME SA-187 Gr.5 and ASME SA-336 Gr.5, I have noticed that, in ASME II Part D they are caracterized by different values on Maximum Allowable stresses, altrough I haven't found any reference about the reason why difference is shown, especially considering the fact that ASME II Part A1 gives the possibility to use, for large forgings ASME SA-366.
I have noticed the difference in the percentace of carbonium for Gr.5 and Gr.5A, that might explain the difference between the grades in SA-366 but I can't related, with same heat treatment, the difference in mechanical properties with SA-182 Gr.5, considering the fact that it is the only grade that shows a difference between these two materials.
Does anyone know why exist that difference in mechanical properties?

Thank you in advance

 

[geesaman.d]

Well for one, SA 336 allows for parts over 10000 lb and SA 182 does not. For grade F5, the ductility limit, yield strength, and tensile limits aren't identical.

Skimming the two standards I see a number of minor differences. They're very similar overall but definitely not the same.

 

[MchDesign]

Thank you geesaman for your answer,

Definitely they are very similar but not identical, but considering che chemical composition and the heat Treatment in the production process (SA-366 shall be annealed or normalized and tempered and SA-182 annealed or normalized and tempered) is that possibile that only a little difference of Sulphur Max in the chemical composition makes a difference in almost 2o MPa in the allowable stress?
And why this difference is only for Gr.5 and not for other grades?

 

[Chumpes]

hello
why would you want these grades to be identical ?
regards

 

[mrfailure]

I need to say explicitly that SA-187 does not exist (equivalent ASTM A187 for heat exchanger/condenser tubes with Grade 5 similar composition was deactivated in 1940). I think this is a typo and you meant SA-182 "Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service". This is a little different from SA-336 "Specification for Alloy Steel Forgings for Pressure and High-Temperature Parts" as SA-336 is for the the overall forgings while SA-182 is from the parts subsequently fabricated from those forgings. This determines which specification is applicable for your application.

 

[MchDesign]

Thank you all for your responses,

I apologize, it was definitely a typo and I meant SA-182 Gr.5, both in the title and in the first post.

I asked because we usually order main flanges with specific dimensions in ASME SA-336 (and tube sheets) where, specifically, tube sheets receive machining in our workshop.

A NoBo pointed out to me that the correct material was SA-182 (instead of SA-336), partly because the allowable stress (for Gr.5) was quite different, considering ASME VIII Div.1 Ed.2023 as the design code. e. In accordance with ASME II Part.A for SA-182:

"That specification includes flanges, fittings, valves and similar part to specified dimension or to dimensional standard" and "product made by this specification are limited to maximum weight of 10 000 lb, for large product refer to SA-336": we considered the SA-182 for standard product and SA-336 for customise products, but from that paragraph I get that SA-182 is better than SA-336, till 10 000 lb.

14 May 24 13:48 SA-336 is for the the overall forgings while SA-182 is from the parts subsequently fabricated from those forgings. This determines which specification is applicable for your application.]

Therefore, the best material for a product such as a tube sheet, which would be subsequently drilled and milled, might be ASME SA-182, instead of ASME SA-336, which would not allow for subsequent machining. Have I understood this correctly?

Is the same concept applicable to ASME SA-350 and ASME SA-765? Because again we have the exact same problem. with SA-350 for standard products and SA-765 for special sizes.

https://www.eng-tips.com/viewthread.cfm?qid=519153

Thank you so much in advance