PetroStreet

In one of our applications, we have to conduct Dye Penetrant Testing at temperatures greater than interpass (200-250 deg C) on low alloy piping.
The main reason is to assure if the welding is free of significant surface defects as the weld joints are in thickness > 50 mm and we do not want any major repair after conducting radiography.
Also, the weld metal temperature cannot be brought down from interpass temperature as it is a WPS requirement for A335 P11/P22 piping.
What are the requirements and what does code say about this?

Thanks in advance.

The requirements have been laid in ASME Sec. V. Normally, for standard temperatures, DPT can be used in between 5 deg C to 52 deg C.
For your case, you have to go through ASME Sec. V T-653 and its Appendix III. You have to qualify the procedure and to check the capability of penetrant to reveal defects at upper and lower limit of temperature you may encounter in your application.
Follow the requirements as stated in T-653 and its associated Appendix III.
See table T-261 also which enlists all the essential and non-essential variables for DPT.

Hope this would help.

We have had an experience of carrying out DPT at around 150C with Diffutherm DPT Chemicals having design capability to use upto 200C. You can check these products at: www.diffu-therm.de

Regards - Qaisar

Qaisar,
Specifically which product of Diffutherm are you using?
Did the manufacturer supply you the qualification procedure also as mentioned by Ashfaq?
If yes, can you just provide me a copy of the same?

Thanks.