re-astablisch mech. properties after heat treatment

[MDutch]

We have a CS pressure vessel for service in severe H2S environment (NACE M0175), designed acc. ASME VIII-1. Complete vessel will receive a PWHT after fabrication.
Shell/head material (15mm thick) is A516Gr60-dicrest 5 and is delivered off mill in normalised condition. Material certificates indicate mech.properties were carried out in normalised and and stress relieved condition.

Heads are cold formed and received an additional normalizing heat treatment after forming at 920 degrees Celcius.

Acc. UCS-85 test specimens need to be provided which have to receive the same heat treatment as the heads did.

My question is if, acc. ASME VIII-1, it is required for the head material to re-establish/test mechanical properties of the material after the normalizing heat treatment performed after forming? Which paragraph of the ASME code gives such a requirements?

Or, can the mechanical properties of the original material certificate be accepted. Than what is the use of the required test specimens..?

Thanks for any input/comments.

 

[metengr]

MDutch;
Please review ASME Section VIII, Div 1, Part UCS, UCS-79,and UCS-85. In UCS-85, any thermal treatment that exceeds 900 deg F (480 deg C) shall have test specimens to simulate the thermal treatment.

The reason is that you are altering the original structure of the steel by re-normalizing, and you might not obtain the original mechanical properties as per the MTR.

 

[MDutch]

metengr,

I did review UCS-79 and UCS-85, and understand that test specimens are required, but i.m.o. this still doesn't tell me that the test specimens shall be used to perform tests to obtain mechanical properties after the heat treatment...

In our Dutch pressure vessel code we have a requirement called "material testing in final condition"...

Where exactely does ASME specify that after re-normalizing you need to do "material testing in final condition" on the test specimens as described in UCS-85..?

Or am I missing something.

 

[metengr]

Please review UCS-85 (c)
....The kind and number of tests and test results shall be as required by the material specification.....

So, review the specification for the type of mechanical tests. I don't believe you meet any of the exemptions listed in UCS-85(c) since your thermal treatment is above the lower critical transformation temperature.