SA515-70

[engpes]

I have a vessel that was constructed in 1972 with SA515-70 material shells(1.8125" thick). I am adding (4) nozzles to this vessel and am having issues with the MDMT.

The original U1A does not specify the MDMT and only has an empty blank that states "MDMT when less than -20 F." It is my understanding that this older version of the ASME code did not have specifics on impact testing exemptions. I am running the vessel in Compress, and am getting a minimum MDMT of +84 F for the SA515-70 material. This well above the minimum operating tempterature.

My question is, can I evaluate the new nozzle alterations with the current (2013) version of ASME VIII, Div 1? Even though the current version of the code does not impact test exempt SA515-70 material?

 

[gr2vessels]

Think engpes, think!
The world has evolved and we must use the benefits of the today technology advances, hence it is normal to use the latest design code.
However, you are talking of modifying an old vessel, not designing a new one. Your guide code is not ASME VIII, but API 579. ASME VIII is the code for designing new vessels only!
Come back with relevant questions, once you are familiar with the requirements of API 579.
Cheers,
gr2vessels

 

[Duwe6]

Yep, another eng led astray by software. The U-1 says "-20°F" -- don't argue with it, and especially don't allow fancy software argue with the U-1.

Nothing in ASME has been rescinded in the period from the 70's until now. Thus your documentation [U-1] signed by the AI matters, and COMPRESS just gave you a ridiculous answer. Don't believe software when it gives ridiculous answers.

 

[metengr]

I might clarify that the document necessary for this modification is API 510 or you can use the NBIC, Part 3. You need to review this and determine what is required regarding adding four nozzles - repair or alteration. I will let you figure that out through API 510 or the NBIC Part 3.

 

[weldstan]

As long as you use the original design allowables (no rerating with the current) inj your calcs, the MDMT of -20F is applicable.