American Welding Society Forum
Does anyone know the lower transformation temperature for ASTM A 333? Pipe flange connections are subject to stress relieve after welding. The ASTM standard limits the stress relieving to 1150 degree F. Parts were already stress relieved at 1350 degree F. Question: Did we "stress relieve" above the lower transformation temperature?
Any comments are appreciated.
I'm going from memory, but if you are referring to a carbon steel (P1), the generally accepted lower transformation temp is 1330 F.
We had to deal with this situation (PWHT of carbon steel at 1350 F) a short while ago on an ASME Section I project. To prove the elevated PWHT did not affect the P1 base metal, this is what we did:
Heat treat stock tube material from each heat of material used in the project (6 different pieces of tube stock) at the same (elevated temp - 1350). Perform tensile testing on each piece. Our rationale was that if the metallurgy was negatively impacted, the tensile strength would be reduced. On the basis of acceptable tensile testing results, we were able to accept the elevated PWHT temperature. This resolution was accepted by our AI.
Question: How did the PWHT temp get assigned at 1350 instead of 1150?
The subcontractor who welded the parts actually had these parts heat treated at this temperature.
Anyway, thank you for the answer
Which 333? This specification has anything from standard C steels to 9Ni. The lower transformation will significantly vary. If you're talking about one of the C steels you are cutting it very close and probably did violate the lower transformation at least in a portion of the material, since temps will not be homogeneous throughout.
If your talking one of the Ni steels i'm certain you violated it.
If it was carbon steel, you can use the equation below to estimate. I'm not sure what the range of composition it is good for when you get into higher alloy stuff.
What Grade? The tempering temperature requirements in Code and Standards are typically minimum values and unless a maximum value is specified, the lower critical transformation temperature is the upper limit. I reviewed SA 333, and there are very specific requirements for heat treatment, and alternative heat treatment to assure specified impact properties for the various grades. What you have by heating to 1350 deg F is a serious nonconformance and must be dealt with accordingly.
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