ASME PRESSURE VESSEL SHELL WITH SPIRAL WELD

[mancini]

We have a pressure vessel supplier which asked us to use "inclined welds" in some shell elements from a pressure vessel, so in accordance their understanding as in ASME UW-3(a) it is informed that a spiral weld (type A) on the shell of a pressure vessel can be used, please may you inform your understanding about:
a) Is this kind of spiral weld, type A, valid to the pressure vessels cylinders and cone geometries?
b) May someone inform if is usual to use the spiral weld on the shell of pressure vessels?
c) In accordance with ASME definition the spiral weld is "a weld joint having a helical seam", do this mean that any inclined weld on the shell can also be used in a pressure vessel element?

 

[Guest102023]

Are you talking about weld overlay?

 

[mancini]

No, I'm talking about the shell main weld (see UW-3)

 

[stanweld]

UW-3 (a) "Category A. Longitudinal and spiral welded joints within the main shell..."

What is it that you don't understand?

 

[SnTMan]

mancini, I have never seen this used, however I can't say it is not common in some classes of work.

a) Yes
b) See above
c) Assuming shell is cylindrical or conical, I would interpret as, Yes

Regards,

Mike

 

[mancini]

Hi stanweld and SnTMan that is the point, besides there is the information in ASME where it is informed that it is possible to use the spiral weld for shell welded joints, in almost 30 years working with different pressure vessels design codes, I have also never seem this similar kind of solution, to me seems to be also a low cost and low quality solution to be used in a pressure vessel.

 

[SnTMan]

mancini, "...a low cost and low quality solution to be used in a pressure vessel"

I'd have to agree with that statement.

Regards,

Mike

 

[SnTMan]

Except maybe for some type of mass-produced, commodity work.

 

[gr2vessels]

My two cents,
I haven't seen either a such construction, but I can't fault it either. In the end of the day, all that counts is the correct design in accordance with the code and ensuring the safe use of this equipment. Perhaps is not a conventional construction, but you can always grind the welds and paint the shell for total masking of the seam.
Hope I'm not upsetting anyone, but the progress is always coming from the people who bring some novelty. If you save a buck without compromise of safety, why not?
Cheers,
gr2vessels

 

[stanweld]

While I have seen such construction in the past 40 years, it has been so seldom that I would have to say it represents less than 0.01% of vessels constructed.

 

[Duwe6]

One of the reasons for the scarcity of spiral-welded vessels is that the seam is deemed to be longitudinal for RT purposes. That's a LOT of weld length to x-ray.

And due to the notorious history of badly-welded spiral-seam pipe, I would refuse to accept a vessel made with a spiral weld without 100% TOFD or UT. RT misses too much LF - lack-of-fusion.

 

[Guest102023]

Help me please, I know about spiral-weld pipe and spiral strip cladding, what would be the point of a spiral weld in a pressure vessel (pressure boundary)?

 

[gr2vessels]

Gents, please note in the OP, the wording;- 'use "inclined welds" in some shell elements', ie. only SOME, not entire shell. This could be just because it fits better in the component lay-out on the standard plate size. Probably the manufacturer doesn't want to buy a whole new plate for a small cut, so it fits better a spiral weld, if is allowed by the code. Since the code doen't prohibit this design, he's asking 'mancini' for acknowledgement rather than approval. I'm assuming the manufacturer is in full understanding of additionl NDE, so I can't see anything wrong in giving him the go ahead.
Cheers,
gr2vessels

 

[mancini]

Hi gr2vessel and everybody,

You understood correctly what we have faiced with our supplier, they have used in some sections the "inclined" welds in order to minimize the amount of material to be used (in the case were cone section from big equipment), so they asked us the approval of their detail drawings. The supplier also received the approval from an ASME third part inspector for this detail. So based on ASME UW-3 and ASME inspector approval, besides understanding that this is not a good practice, we have accepted the solution and requested to consider these inclined welds as ASME type A and to be executed the necessary inspections to cover the joint efficiency from the calculation. May be in the future vessels, we have to inform ,in our specifications, that this type of weld is not accepted.

Thanks a lot and best regards.