Weld Buildup - Legal? 1

[weldtek]

There's no question that ASME Sec VIII Div 1 allows weld buildup under certain conditions. Specifically, it is allowed to 'restore' base metal for strength, and, for other purposes such as transitions in thickness.
My question is, does the Code allow a fabricator to take a piece of plate say 1" thick and use weld metal buildup to increase it to say 1.25" thick?
My AI says no, it use is limited to 'restoration', and, I concur, however, I have a customer who argues otherwise. By the way, the customer has purchased an item which was the correct thickness, but, after a change in design criteria, no longer meets required design thickness.

 

[jte]

folks-

As I stated before, I have no stake in the particular issue which has fostered this discussion. I find it interesting and try to keep my options open since I have found that sometimes unusual solutions are safe and reasonable and with the right caveats are the best path forward from a messy situation. Having said that...

vesselfab-

I understand and admire your perspective. I don't always have the luxury of saying "no" without providing a very strong argument. Yes, I've often taken your position. I just won't be quite as rigid if I come across a situation in the future where some weld buildup will solve the problem.

metengr-

I'm also an owner/user, so we have similar responsabilities. I also have experience in the E&C world which is where I'm drawing my examples from. I understand your concerns with possible lack of fusion defects. Let me ask you if you will take the same stance for a repair of a severely corroded shell or head? If you would allow the repair to proceed via weld buildup, how is the situation different from new construction?

weldtek-

Not at all unusual to have ladders and platforms designed after the PO is issued... So it sounds as though compressive stresses are governing the design between the bottom shell course and the skirt (presumably welded on the head just below the tangent line), so the SF on the head is failing the calc's. What is the measured (UT) thickness of the SF? The min calc'ed thickness will be governed by the knuckle region, and the head was no doubt formed from a slightly thicker plate. Guess that's the first straw I'd grasp at. Secondly, If I were to weld overlay with a corrosion resistant material would the CA that I can now use for strength be sufficient to get you over the hurdle?

jt

 

[metengr]

I'm also an owner/user, so we have similar responsabilities. I also have experience in the E&C world which is where I'm drawing my examples from. I understand your concerns with possible lack of fusion defects. Let me ask you if you will take the same stance for a repair of a severely corroded shell or head? If you would allow the repair to proceed via weld buildup, how is the situation different from new construction?

Repair requirements would be in accordance with the NBIC. So, yes, I absolutely would consider a weld build-up repair of a corroded or wasted head provided a complete volumetric examination of the weld build-up (ultrasonic examination) was used because this would be my specific requirement to satisfy the NBIC regarding selection of a suitable method of NDT (in addition local RT may be required, but only in the area the weld build-up was placed over an original vessel weld that was RT based on the original code of construction requirements, or UT could be used - this is the call of the Inspector and capabilities of the NDT personnel).

Keep in mind that the NBIC has a requirement for extensive repair of wasted areas in that it is the judgement of the Inspector that the amount of weld build-up has to be taken into consideration to determine if the strength of the component is impaired. I believe this could be done by calculations and backed-up by more extensive NDT (volumetric examination).

Going back to original design conditions versus attempting to re-rate a corroded or wasted component using weld build-up are obviously repair versus alteration schemes. The alteration would require, in my mind, calculations, coupon testing and enhanced NDT and hydrotesting. Of course, the final say is with the Jurisdiction.

I am always open to innovative repair methods, like the above.

 

[JoeTank]

I haven't read every post here but if the addition of local loads (due to platforms) is the problem, why not try stiffening rings or repads at the supports?

Joe Tank

 

[weldtek]

JTE,
Additional available thickness is neglegible.

Joe,
We have considered that option, but, in this case it won't work.

We will remove the entire straight flange and lengthen the shell to make up the difference.
I've requested my agency submit a question for interpretation.