WPS/PQR for SA 335 Gr P91, chrome molly pipe

[James Scrufy]

Since I have been engaged as a welding coordinator in a power plant, it is the first time that I need to issue WPS and PQR for welding material SA 335 Gr P91. Is there anyone that could advise me or give me some tips regarding this welding?

[wgadmin]

Some tips:

1. use low residual filler metals that must be purchased with test reports showing the actual chemical analysis for the specific heat/lot that you have been purchased.
2. get a good purge for the root using 100% argon not only inside but also on the back side preferring a decent flow volume.
3. give special attention to the preheat and the maintenance of the interpass temperature (a range of about 200 to 300°C is recommended) as well as to the PWHT. These should be selected based on the applicable design code.
4. preheat a minimum of 70 - 80 mm from either side of the joint using induction with which you have the multi thermocouple monitoring feature to record additionally the PWHT after the weld is completed.
5. after welding is completed, the joint should be allowed to cool slowly to at least 90°C prior to PWHT.

For more information you could have a look to the below link:
http://www.sperkoengineering.com/html/G ... 010-05.pdf