SA-350-LF2 Cl.1 MDMT Lower Than Specification 1

[nashki]

Hello,

I am working to design a pressure vessel using ASME Section VIII Division 2 2021 edition with design pressure 600psig, design temperature 270°F, and MDMT -66.2°F.
The material of construction is SA-350-LF2 Class 1.
As per material specification, the impact test temperature is only -50°F.
Can it be used for the MDMT -66.2°F?
Is part 3.11.2.5.(a) applicable to determine the reduction?
If yes, is the stress ratio calculated as per 3.11.2.5(d), Stress Ratio = Design Pressure / MAP at the MDMT?
How to determine the MAP at MDMT?

 

[akpipelineengr]

Follow 3.11.2.6 to reduce MDMT of impact-tested material, like A350 LF2 CL1. If that doesn't get you there, you'll need to specify supplementary CVN testing to achieve your MDMT.

 

[weldstan]

We purchased A350 LF2 with impact testing at -60F over 30 years ago for our -60 MDMT project design. I know of other projects with lower MDMTs where A350 LF2 forgings were purchased with similar requirements possibly as low as your needs.

 

[akpipelineengr]

Yeah, additional testing is pretty straightforward. Just takes $$. I've purchased A333 pipe with -80F CVNs for specific applications.

 

[nashki]

The original material SA-350-LF2 CL1 is impact tested at -50F
I have tried run the calculation in Compress. The stress ratio is calculated per 3.11.2.5(d) = MAWP of the entire vessel / MAP of the item itself (Flange)
Then it get reduction by 3.11.2.6 and from table 3.17, so the design MDMT of -66.2F is acceptable

Since the material is tested at -50F and get reduction by the code, shall we perform the production test for this material?
If yes, what is the production impact test temperature? at -50F or -66.2F?

 

[weldstan]

You purchase the material with impact testing at -66.2 F.