What is the Minimum design metal Temperature (MDMT) of the piping system under constrcution?
Ask your designer or check on the drawings.
The impact test temperature can not be higher than the MDMT unless you can get some credit using the provisions of ASME B31.3 chapter 323.3
Dr. G. Dilintas
I&F Regional Technical Manager
Bureau Veritas Piraeus - Greece
Tel: +30 210 40 63 113/4
Fax: +30 210 40 63 118
Hi, You are correct, Minimum refers to the one cycle for which this part will expose until final work shop PWHT. hence mill test certificate shall include this. Max. SPWHT, refers to additional cycles of heat treatment that are reserved for future repairs during equipment lifetime. Again, these simulated no. Of cycles shall be specified in MTC. The idea is we need to make sure that steel mechanical properties are not compromised upon exposure to multiple repairs (i e 4 cycles in your case). One could say, if steel is subjected to 4 cycles and is ok, then it should by defacto be good for one cycle, yet, this is wrong assumption cause mechanical problems and microstructure of materials varies accordingly based on no. Of cycles for which material will expose. This is apparent in alloy steel and especially for impact test values as an example. In your case, this forged CS with properties before PWHT can be understood to be " as forged" condition (i.e. Wit...
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