PWHT of SA 387 CL. 11 Plate

[JIPMKWA]

Good morning,

We have some structural plate to weld in the back pass of the boiler ( economizer ) that supports the economizer itself. It has broken free and we are going to band-aid it until a more permanent fix can be administered at a later date.

We are going to be welding vertical plates ( SA 387 CL. 11 ) down to the top flange of a plate girder ( of the same material ). Both members are around 1 1/2" / 1 3/4" thickness. I could not find SA 387 in D1.1 to see what material number (P#) it was classified under for PWHT/PreHeat requirements. However, in ASME IX, SA 387 is listed as a pressure vessel plate and is a P#4. All of our welding procedures are qualified to ASME IX but in my mind this is a structural weld.

My question is - Should we weld this with our ASME IX procedure for P4 material and then heat treat it in the same manner as a P4 material ? Or would it not need PWHT'd because it is a structural weld and not a pressure vessel ( boiler proper ) ? Or is there any way we can get out of PWHT all together ( this is what we are hoping to do so the unit can be brought back online quickly )


Thank you for your time

 

[JIPMKWA]

I should have mentioned our intent is to weld these plates as a Single bevel - CJP to the top flange of the plate girder, in the horizontal position.

 

[metengr]

What you described would be a structural weld repair and under AWS D1.1.

 

[Duwe6]

RE: D1.1 -- the reason that P4/Cl.11 material was not in D1.1 is because it requires PWHT. If I got stuck in your spot, following the rules in Sect IX, would make the biggest weld that will not require PWHT [eliminates the possibility of a CJP], or plan on PWHT. Or engineer my way around welding directly to the P4 material.

Yes it is 'structural' in nature, but since it requires PWHT to be safe to use, neither AISC nor D1.1 will recognize it.

 

[weldstan]

Think about using a temper bead welding procedure per QW-290 of ASME IX to preclude the need for PWHT. Or PWHT locally. Welding with adequate preheat/interpass controls and F43 filler metals have also been used to make similar welds without PWHT.

 

[metengr]

Section IX does not provide rules for PWHT, only means to qualify a WPS with or without PWHT. With that said, this is a non-code, structural weld repair and Section IX is not prohibited from use. If you want to avoid PWHT you can qualify, as weldstan mentioned, a temper bead procedure following QW-290.

 

[JIPMKWA]

Thank you for the replies guys. We have a temper bead procedure for welding P4 material. The problem is - It is only wualified for 3/32" and 1/8" electrodes. With the amount of weld that we have to deposit ( ~ 5 of these 1 3/4" x 10" CJP plates ) , we were hoping to be able to use 3/16" or 1/4" diameter electrodes.

I have never personally qualified a welding procedure but I am reading up about temper bead procedure's and it looks like it is very involved with hardness testing and macroetching. I don't see electrode diameter being an essential variable though ?

 

[Duwe6]

Rod - electrode - size is an essential variable for Temper Bead, via the 'back door'. Temper Bead is dependant on heat input; bigger rods demand more current to maintain an arc, thus more heat input.