Pwht exceeding Tempering temp.

By jholbert23 Date 01-15-2015 19:58

What code or standard states " PWHT temperature cannot exceed Tempering temperature? Our PQR's heat treatment MTR states our Tempering Temp. is 1160 & 1200 f degrees but the PWHT temp. is 1225 +-15. I know its a rule of thumb but I would like to see the stated facts, by the way we weld 4130 to Inconel if that is any help.

By Lawrence (*****)

Date 01-15-2015 20:51

Which flavor of Inconel?

By jholbert23 Date 01-15-2015 20:54

625

By Lawrence (*****)

Date 01-16-2015 13:37

I don't think you are going to find a code or standard that speaks directly to heat treatment of the dissimilar alloy combination you bring to the discussion.

Having said that, welding Inco 625 to 4130 is not all that uncommon.

Unlike it's cousin Inco 718, Inco 625 is not precipitation hardenable so requires fewer safeguards, pre-weld annealing, and post weld stress relief than some other choices for overmatching.

I suspect the post weld heat treatments are entirely for the benefit of the 4130, but the temps themselves used to perform the work and how to calculate them are above my pay grade and will require engineering support in full knowledge of service conditions and part geometries I'm sorry to say.

By 803056

Date 01-15-2015 21:46 Edited 01-16-2015 18:15

Why inquire about a specific welding standard if it does not apply to your work? That is like asking about the licensing requirement for driving a tractor-trailer when you only need to ride a bicycle. One has nothing to do with the other.

Codes only apply when the customer/Owner invokes them.

That is not to say the codes and standards are not founded on good welding principal or practices, but one cannot arbitrarily impose code requirements unless one is developing the project specifications or using the code as a rational basis of developing specific requirements. The shortcoming of a code or standard is they do not include the reason for the requirement.

Best regards - Al

By Lawrence (*****)

Date 01-16-2015 13:08

Al said:
"The shortcoming is of a code or standard is they do not include the reason for the requirement."

Boy is that ever true sir!

I recently discovered a thing in D1.1 section 5 that is giving me a migraine. It's so bad I can't even talk about it :) The problem, not the migraine.

Why oh why indeed!

By SCOTTN

Date 01-22-2015 13:42

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