A335-P22
A335-P22
(OP)
My concern is whether or not to preheat pipe before thermal cutting. As per API 582:
8 Preheating and Interpass Temperature
8.1 Preheating, where required, applies to all welding, tack
welding, and thermal cutting of ferritic steels except for thermal
cutting of P1 materials. Minimum preheat requirements
shall follow the applicable code such as ASME Section VIII,
Appendix R; ASME B31.3, Table 330.1.1; and AWS D1.1,
Annex XI. Any recommendations or requirements for preheat
listed in the relevant code shall be considered mandatory.
What are the possible dangers (metallurgy) of not preheating to code temperature before cutting?
Note: The cut pipe will eventually be welded and recieve PWHT as per B31.1
Thanks for your help!
Mike
8 Preheating and Interpass Temperature
8.1 Preheating, where required, applies to all welding, tack
welding, and thermal cutting of ferritic steels except for thermal
cutting of P1 materials. Minimum preheat requirements
shall follow the applicable code such as ASME Section VIII,
Appendix R; ASME B31.3, Table 330.1.1; and AWS D1.1,
Annex XI. Any recommendations or requirements for preheat
listed in the relevant code shall be considered mandatory.
What are the possible dangers (metallurgy) of not preheating to code temperature before cutting?
Note: The cut pipe will eventually be welded and recieve PWHT as per B31.1
Thanks for your help!
Mike





RE: A335-P22
"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein
RE: A335-P22
Thanks for your prompt response. I have been looking at the CCT diagram for P22 and considering the thermal cutting is done in a shop I am questioning whether the cooling rate is fast enough to produce Martensite. Is Bainite equally susceptable to cracking?
Does anyone have hardness and strength data for the different microstructures (Martensite, Bainite, Fine/Coarse Pearlite) for P22?
Mike
RE: A335-P22
The mechanical properties of the various microstructures can be easily looked up, but there are a lot of factors which will influence them.
"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein
RE: A335-P22
RE: A335-P22
RE: A335-P22
Yes, the flame cut edge is cleaned up by a grinder prior to welding. How do you ensure that sufficient material is removed? In other words, how will a welder determine when enough material is removed to eliminate any cracks and remove all of the martensite.
Mike
RE: A335-P22
RE: A335-P22
If preheat was not applied or used for some reason, I would recommend 1/4" removal of heat affected material from the cut edge followed by a surface NDT to ensure no cracks. Typically, 1/4" removal of material would suffice without preheat, and keep a safe distance from locally hardened material. Depending on thickness, you can also perform portable hardness testing to determine if any hardened material remains, the surface NDT would be a requirement.
RE: A335-P22
Thank you all for your input. I think I will request preheat to code temperature prior to cutting for these reasons:
-Preheat will take no more time than grinding off 1/4" of material
-Eliminate potential for lazy welders not removing enough material
-Preheating to code temperature is easily measured and managed
-Peace of mind
Mike