Interpass temperature is the temperature measured after welding of each pass. (please refer for definition of each pass in welding). Normally before you start welding you apply PREHEAT and this becomes the minimum Preheat temperature and after start of welding due to the high Arc temperature the welding heat will be conducted and after completion of one pass say for example Root pass one shall measure the temperature on the weld bead(root bead). Like wise for each pass the interpass temperature shall be measured. Welding shall be performed for all passes between minimum Preheat Temperature and maximum Interpass temperature measured at the start of each pass. Interpass temperature is measured after completion of one pass and whereas welding preheat during welding shall never be less than minimum preheat temperature.
Effect of Interpass temperature on Carbon steel.
1. Higher the Interpass temperature, then slower the weld cooling rate which inturn results in Higher Grain size in the finished bead/weld and lesser the Charpy Impact values.
2. According to ASME Sec.IX, increase in Interpass temperature higher than 55degC than the PQR will be considered an Supplementary Essential variable and requires new qualification of PQR. Any changes in the maximum Interpass temperature within 55degC (PQR) shall be revised in the WPS.
3. Your case 290degC is well within the maximum Interpass temperature of 340degC mentioned in the WPS and so there is no issue.
Thanks & Regards
J.Gerald Jayakumar
On Monday, 23 August, 2021, 08:46:25 am IST, Rameez khan RK <rk.rameezkhan21@gmail.com> wrote:
Hello Experts,
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Can any one tell me about interpass temperature for carbon steel pipe as [per code and standards.
WE facing one issue here our Approved PQR interpass temp. is 290 but in WPS its mention 340 c so please defined and what is actually interpass temp as per codes per standards.
thank you
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