PWHT and Temper parameter for pressure vessel
PWHT and Temper parameter for pressure vessel
(OP)
Hi,
I have got below PWHT requirement from one of my client which i have never encountered before. On the face it seems to be simple, but when i start to calcuate the exact values of permitted tolerance i get lost,
“Welding procedures for all materials subject to PWHT shall be qualified to be adequate for the total PWHT holding time that will be used for fabrication and for one additional PWHT cycle in accordance with ASME Section-VIII,Div-1. The PWHT of welding procedure test samples shall qualify production welding that is within 2% of the time and temperature of the PWHT cycle or within a Tempering Parameter of 0.2, whichever is less.”
I would like the permitted values on a sample case as per below,
Construction-
Carbon steel , Section-VIII Div-1
Vessel =70 mm thick (which calls for 135 min duratin for single PWHT cycle)
Say Soak temp= 610 Deg C
The problem here which i am facing is, you have an additional PWHT cycle also as an requirement during procedure qualificaiton and also the client is asking 0.2 permitted variation on the PWHT cycle of production welding.., again adding another dimension by stating “whichever is less” to complicate the stuff..
if you take total duration with additional PWHT, then there is no way to fit 2% of production cycle also..I am pondering what exactly the client needs out of this. Please throw light on this riddle..
I have got below PWHT requirement from one of my client which i have never encountered before. On the face it seems to be simple, but when i start to calcuate the exact values of permitted tolerance i get lost,
“Welding procedures for all materials subject to PWHT shall be qualified to be adequate for the total PWHT holding time that will be used for fabrication and for one additional PWHT cycle in accordance with ASME Section-VIII,Div-1. The PWHT of welding procedure test samples shall qualify production welding that is within 2% of the time and temperature of the PWHT cycle or within a Tempering Parameter of 0.2, whichever is less.”
I would like the permitted values on a sample case as per below,
Construction-
Carbon steel , Section-VIII Div-1
Vessel =70 mm thick (which calls for 135 min duratin for single PWHT cycle)
Say Soak temp= 610 Deg C
The problem here which i am facing is, you have an additional PWHT cycle also as an requirement during procedure qualificaiton and also the client is asking 0.2 permitted variation on the PWHT cycle of production welding.., again adding another dimension by stating “whichever is less” to complicate the stuff..
if you take total duration with additional PWHT, then there is no way to fit 2% of production cycle also..I am pondering what exactly the client needs out of this. Please throw light on this riddle..





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