ASME sec VIII question

Date 01-10-2007 19:54

We have sub-contracted some vessels to an outside shop. The vessls dwg calls for some grating (walkway type grating) to be welded to the inside of the shell. Our sub asked to substitute the grating because the AI would not allow the grating because carbon content could not be verified, and it seems MTR's usually are not supplied for grating. The dwg calls for SA-36 material for the grating. (a side note - we use the grating all the time in most of our shops in the vessels...no AI problem on our end).

I wrote them an e-mail explaining that for one, MTR's are not required per code (MTR's are only required for plate used as pressurised retaining) and the only reason they would HAVE to have them, is if their QC manual required it., and two, non pressure bearing attachments only require that the material be proven of weldable quality (there is stipulations on material not approved or specified by ASME).

OK, to me, since SA-36 is a spec in ASME, and MTR's are not required by code, and it is a non pressure retaining attachment, as long as the sub purchases, is supplied with, and says that the material is in fact SA-36, what grounds does the AI have to reject it?

Anyone have any input with this situation/experience with sec VIII?

By jon20013 (*****)

Date 01-10-2007 20:01

In general, I would agree with your explanation new tito, however, when you say the grating is welded to the inside of the shell, does it attach to the pressure retaining element? If it welds to the shell, I guess I could agree with AI wanting to verify carbon content...

By new tito (***)

Date 01-10-2007 20:59

A short, very, simplified explanation of the vessel - A shell, two heads, two nozzles, and the grating will be cut to fit the ID of the shell, and be welded inside, to the shell.

By chall

Date 01-10-2007 20:07 Edited 01-10-2007 20:17

I think you made your case very well.

Are you sure the material is SA36, not A36? A36 usually gets our AI in a lather.

I am a little busy just now, but I do believe you also have to consider the charpy impact properties. I don't remember the specifics, but when I can look into it, I'll post my other thoughts.

Charles

edit - my thoughts are on the wrong track. I agree with your position. UG55 takes you to UG4. UG4(b) takes you to UW5(b). That says if the WPS conforms to Section IX, the material is "proven weldable".

By jon20013 (*****)

Date 01-10-2007 21:09

I agree all the way around on this but my statement was simply to the fact that I believe the AI has the right to request MTR's simply to satisfy his/her concern over the chemicals, even if MTR's are not required by code perse they could use the argument of admixture concerns, albeit a weak arguement.

By new tito (***)

Date 01-10-2007 21:12

Ca-Ca, I think that may be were I'm had - I'm sure it would be A-36, which IS NOT a spec covered in ASME unless the acceptable ASTM ed. and ad. is used, which would be hard to prove without an MTR, I guess, unless the mill, vendor, and subcontractor say it is SA-36, or at least meets the requirements of SA-36, right? I mean, if you order SA-36 from a vendor, do not request MTR's because they are not required, the vendor ships the grating and the shipping documents say SA-36 grating, where does the AI have authority? I understand he can pretty much accept or reject anything, if he's correct, I just want to make sure I am on the right thinking track here.

By new tito (***)

Date 01-10-2007 21:16

One more note, the requested substitution was to use expanded metal (cut to fit the ID) welded to SA-36 flatbar, which the flatbar would then be welded to the shell.

My point being, flatbar is SA or A-36, the grating is SA or A-36............see my point???

By jon20013 (*****)

Date 01-10-2007 21:46

I don't mind arguing with our ANI / AI, but I try to chose my battles wisely.

By chall

Date 01-10-2007 22:01

The AI has the responsibility to make sure it is safe. He has the right to make you convince him that the material used is acceptable by code, and that your system of traceability satisfies the code. He can be as tough as he has to.

If you can't talk him into accepting what you have already presented to him try this: Run a fillet weld PQR using a sample of the flatbar you used in the vessel, welded to a piece of SA516 (shell). We have had to do this a number of times when traceability to an MTR is not possible, for non pressure part attachement materials.

He will first have to accept that the piece you use for the test is representative of the material used inside the vessel. Once that barrier is passed, passing a fillet weld PQR is a snap. Since the welding characteristics of the material are similar to P1, a welder qualified for P1 (using the same process, etc. as were used in the fillet weld PQR) is qualified to weld the attachment weld.

I hope I'm not muddying the waters too much.

Charles

By new tito (***)

Date 01-10-2007 22:18

OK, thanks guys for the help. I'll update if I hear anything back from the vendor and/or the AI.

I wanted to get some info from some more experienced ASME gurus, to see if I was "choosing my battle wisely", or if I may end up looking like an a$$ arguing with an AI.

CYA

By darren

Date 01-10-2007 22:12 Edited 01-10-2007 22:19

When we are worried about contamination of the shell material from an unknown steel such as grating we just use a repad, weld the known acceptable metal to the end of the grating and then weld the acceptable metal to the shell or reverse order depending what is feasible.
also remember that if the quality control agents did'nt complain once in a while then they would appear dispoable which of course is nonsense because they are a very important part of the whole manufacturing process. In a perfect world they and we get along come up with reasonable solutions and we carry forward in a seemless process. haha made you laugh
darren
p.s. i realise it was already stated as a solution( i read the comlete thread after answering) but i like to pretend i'm smart sometimes