ASME SA-350 & ASME SA-765 - standard product and specific dimensions

[Mich_A]

Hello All,

I'd want to show a doubt that comes for standard forgings and large forgings, in particular regarding carbon steel at hight temperature and low temperature.

Considering the ASME SA-350, that specification covers carbon and low alloy steel forgings, requiring notch and toughness testing for piping components: in ASME II Part.A: in particular this specificatio covers flanges and forged fitting and valvles for low temperature service, made to specific dimensions, or to dimensional standard, such as the ASME and API.

I'd like to ask you if "specific dimensions" include also tubesheet and girth flanges, or large product in general (considering also the fact that in the title this materials appears for piping only). That because, considering the material ASME SA-765 "Standard specification for Carbon Steel and Low Alloy Steel", that specification explicitate tube sheet, covers, channels barrels and integral forged channels, so seems to fit better than ASME SA-350 for large products. We usualy order flanges with specified dimension made by ASME SA765 for the reason above and standard forgings made by ASME SA-350, althrough "specific dimensions" for ASME SA-350 might include parts with dimensions specified by the purchaser.
Do you have any excperience with that? Which might be the best choice?

This difference is better explicitate for ASME SA-105 where that specification include "flanges, fittings, valves and similar parts ordered either to dimensions specified by the purchaser or to dimenional standard such as the MSS,ASME and API. Made product by this specification are limitet do a maximum weight of 10 000lb,; large forgings may be ordered to ASME SA-266. In this case, it is explicitate that tubesheet and hollow cylindrical forgings for pressure vessel shells are not included within the scope of this specification". In this case we use ASME SA-266 both for tubesheet and for girth flanges.

Is that concept extendible also for ASME SA-350 and ASME SA-765?

Thank you in advance,

 

[GD2]

OP,
What are you designing? I mean what's the equipment design code.
ASME II Part A is a list of ferrous materials. It's a global list. It doesn't mean that you will be allowed to use any listed materials under it to any Code sections. Example: materials allowed by ASME Sec VIII Div 1 will not be exactly same for Div 2 and Div 3.
Obviously, you can use any material allowed by the Code. Typically SA-350 and SA-105 are for small sizes. If you can use these parts for small flanges and fittings you can use it. Where you don't get the size, use SA-765. Make sure that it is listed in the Code for use and meet the material requirement, specially in terms of MDMT.

GDD
Canada

 

[Mich_A]

Thanks for the answer GD,

I'm sorry I forgot to mention the design code: ASME VIII Div.1 Edition 2023

I am designing an heat exchanger but my question is much more generic, I mean, these materials apply both to heat exchangers but also to vessels, considering standard flanges or flanges with specific dimensions.

My doubs is that, SA-350 specifically mention in the title 'SPECIFICATION FOR CARBON AND LOW-ALLOY STEEL FORGINGS, REQUIRING NOTCH TOUGHNESS TESTING FOR PIPING COMPONENTS" so it looks like as if that material cover only piping components, so I presume standard flanges. However, that specification, said:

"No limitation on size is intended beyond the ability of the manufacturer to obtain the specified requirements" and

"They are made to specified dimensions, or to dimensional standards, such as the ASME and API"

So it might be used for main flanges and tube sheet, if the manufacturer is able to guarantee the requirements (I've seen many tube sheet and non-standard flanges with this material) . But that applicability would collide with "piping components" and for that reason SA-765 seems to me a better option for tube sheet and flanges with specified dimensions.
Another fact is that SA-765 is not recalled in that specification (SA-350), and that's quite confusing to me because I expected something similar to SA-105 to SA-266.