ASME Sec VIII Div 1 full pen weld on a mixer 1

[jayinwww]

Our company has been asked to cut out some mixer 7mm plates from inside a mixer, these are non-pressure components that are welded to the shell, we will cut the plates 1" from the shell and not touch or weld on any pressure boundary. Since we are cutting these mixer plates, when we put that back in, they will now be full pen welds. I understand this is not structural steel, which structural steel may require UT, backing plate, or grind out the root and reweld etc. Since this isn't structural steel code. Is there typically any addition NDE requirements for a full pen weld for ASME Sec VIII Div 1 non-pressure plates inside a mixer? We just have been asked to do PT on the final welds.

 

[Geoff13]

I'm assuming this is a pressure vessel registered in BC. Your post doesn't give any indication of the vessel size, or how big an opening you're cutting out. I'll assume a reasonably big vessel since you mention 1" plate.

You should contact Technical Safety BC (TSBC) to be certain of their requirements.

I will try to guess a few things they will likely require.
[ul]
[li]I assume you work at an ASME registered company, except if you do I would not expect you to ask this question.[/li]
[li]You will need ASME Section IX weld procedures registered with TSBC suitable for the shell material (P number, impact tested, etc).[/li]
[li]You will need to have the work done by Section IX welders with certification for the welding involved.[/li]
[li]You will need inspectors with the appropriate qualifications. The TSBC AI will let you know what witnessing they want to do.[/li]
[li]This sounds like it will qualify as a "repair" rather than a "modification", so no calculations should be required.[/li]
[li]Weld detail should have the same joint efficiency as the vessel (likely 1.0, but that's just a guess) from Division 1 Table UW-12. Hopefully you have access to the inside of the vessel to do a double sided butt weld.[/li]
[li]RT of the welds should match the original vessel to have the same joint efficiency.[/li]
[li]It will be up to TSBC if they will require hydrotest or if additional NDE is sufficient.[/li]
[li]All the usual paperwork documenting the above.[/li]
[li]I will strongly suggest the opening you cut has rounded corners.[/li]
[/ul]
That's enough to get you started.

Good luck
Geoff

 

[jayinwww]

My apologies, I did a poor job at explaining things. This will require an AB-40 repair, it is a mixer in Alberta. It was a 7mm plate that is being cut 1" away from the shell, non-pressure plate. I was more referring to what NDE may be required. But I believe the work pack is correct that just a final PT will be done. But we will have to perform a full pen weld.

 

[Geoff13]

And maybe I read too quickly. I thought I read a couple of times, but now I understand properly.

Sounds like you're on the right track.

 

[weldstan]

Are the 7mm plates subject to vibration from the mixer? If so you should considerthe effects of fatigue on the weld joint.