decrease working temp

[daridy]

dears
please help me about decrease working temperature for pressure vessel from - 15 C to be - 30 C

this is consider De-rating or Re-rating according to NBIC ?

 

[metengr]

This would be a re-rating and fall under an Alteration under the rules of Part 3 of the NBIC. The reason is that lowering the minimum design metal temperature may increase risk of brittle fracture behavior in service.

 

[daridy]

Dear Metengr
kindly informed that we decrease the working temperature not decrease MDMT

 

[metengr]

So, in other words, your new lower working temperature is indeed above the minimum design metal temperature on the vessel nameplate? If so, nothing else needs to be done. This is still within the nameplate rating of the vessel.

 

[daridy]

yes im still above MDMT
so where the reference to your info?

 

[metengr]

Part 3. 3.4.1 NBIC, read it.

 

[GenB]

Daridi. Why not give the secret: MDMT in advance and we can see the whole picture. "Where is the reference" common sense if you MDMT is stamped and documented by the orig Mfr. And you are between those parameters, you are in compliance,

General Blr. CA,USA