Which grades of carbon steel for MDMT = -52¦C 1

[jaguar69]

Dear all,

I'm wondering which grades of carbon steel are suitable for an MDMT = -52°C for pressure vessel as par ASME VIII Div 1?
I assume that I have to follow the UCS68 rules.
Is PWHT mandatory ?
Impact test value as per UCS68(b) ?
What are the other specific requirements, due to MDMT=-52°C that I have to follow.

Thank by advance for your help

 

[SnTMan]

jaguar69, PWHT is mandatory for service and thickness per UW-2(a),(c) and UCS-56.

If your vessel does not fall under these you MAY PWHT per UCS-68(c) and gain a 30F reduction in MDMT, but it is not mandatory. You may for example be able to gain the needed reduction per UCS-66(b), in which case reduction per UCS-68 is not needed.

You will likely need lo-temp qualified weld procedures, see UCS-67.

To answer your original question the "usual suspects", SA-516-70, SA-333-6, SA-334-6, SA-350 LF2, perhaps SA-105, SA-106-B, and so forth, are potentially usable.

Csn't really answer your last question, too much unknown, except to say:

You will need to carefully read Part UCS, especially UCS-66 and -67, and anything referenced by them to insure you are in compliance.

Regards,

Mike

 

[weldstan]

Add SA-537 to your list. Take off SA-105 and SA-106, although I have seen A-106 which met A-333 gr 6 fine grain attributes.