SA387F11 casing 1

[bryancobb]

We are quoting building a boiler casing out of SA387F11 CrMo
1-1/4% Plate. Info that I have found says to preheat to 300F and HOLD THAT ELEVATED TEMPERATURE UNTIL PWHT.

Is that correct???? Please, someone, tell me how the heck that can be accomplished.

 

[MJCronin]

Does this type of post, asking this kind of question scare anyone else ?

 

[stanweld]

MJCronin:
This and a number of other queries scare the heck out of me but at least bryancobb asked the question; apparantly there may be no one in his company that he can effectively turn to for needed info to perform his assigned task - a pity.

bryancobb:
Assuming you are welding to ASME I or B31.1, you do not need to maintain preheat to onset of PWHT.

 

[xema77]

This is correct, the preheat temp must be maintained until either the final PWHT, an Intermediate Stress Relieve (ISR) or Dehydrogenation Treatment (DHT) to among other things prevent cracking due to hydrogen entrapment. Working with Chrome-Moly Materials is quite specialized, I suggest reading API RP 934/934-C which provides guidelines for working with 1-1/4 and 2-1/4 Cr Materials.

 

[vesselfab]

I didn't think that 1 1/4% chrome required holding preheat until PWHT.

Where in code is this?

 

[boilerone]

First please remove that 'F' in the material specification and replace with 'Gr'. SA387 stands for rolled Cr-Mo pressure vessel plates, not forgings.

I guess holding preheating temperature till PWHT actually means you should never loose this temperature before and during welding plus perform PWHT immediately after welding to prevent cracking.

I don't think canceling preheating to let the plate cool down can cause ANY damage if for some reason welding cannot be performed immediately next. This material is good for a much higher temperature than 300F without changing properties. Just preheat up again and perform the whole procedure the next time when things are ready.

 

[metengr]

Preheat maintenance may be required by either the WPS or traveler, regardless of minimum Code requirements.

Second, does the Code require this? The answer for ASME Section I construction is no. See A-100 and PW-39.

For B31.1 conditionally yes, for P-No 3, 4 and 5A and 5B base materials, see section 131.6 Interuption of Welding and requirements.

 

[bryancobb]

Did I mislead by saying "Boiler Casing?"

This item I'm asking about is a non-pressure component and doesn't weld to any pressure retining item.

It will be neither Section I or B31.1.

Sorry for the confusion.

Bryan

 

[stanweld]

If what you are referring to is the membrane between tubes, that weld is not subject to PWHT. If you are referring to the membrane to tube weld and the tube is of the same material and the tubes thickness is sufficient to require PWHT, that weld is also subject to PWHT and is governed by ASME I; maintenance of preheat until PWHT is not required.

 

[boilerone]

No matter for pressure part or not, cracking is cracking, welding defect is defect.