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UG-14 Limits

UG-14 Limits

UG-14 Limits

(OP)
What constitutes 4" NPS.

As an example, we produce a pressure vessel from 4" sch80 pipe and a flat head weld ed to one end. My interpretation is that the flat end can be made from forged bar (ensuring that the grain flow of the hub is in the correct direction).

However, we produce a stronger model machined entirely from forged bar, it has a larger OD but the same bore. My inrepretation is that this is still 4" NPS.

What would your interpretation be?

RE: UG-14 Limits

No. 4" NPS is what it is, a specified OD of 4.5" for pipe. The pipe bore can vary depending on wall thickness.

RE: UG-14 Limits

Agree with metengr. 4.5" OD is it.

If you cut flat caps off the bar like "cookies" you will have problems.

RE: UG-14 Limits

You are trying to do away with something...
if you modify a pipe in any way size or chemical components, it is not pipe anymore.
you will have to comply with the forging specification.
which you can probably use NPS certified by the forging mfr.
(what about female forging specs) they are heavier than 4in. NPS pipe!


RE: UG-14 Limits

(OP)
I was trying to be a bit cheeky I think, I'd already guessed what your answers would be.

I do think that ASME have been a little hasty, there will be a lot of manuafcturers of small vessels out of titanium or other materials with small grain sizes that are going to struggle to make one-off bespoke vessels because of this new ruling when they don't get any benefit from having the grain formed in the  stress directions.

Maybe they should consider who uses the code and how before they jump in like this.

RE: UG-14 Limits

If you're looking for a get-out-of-jail clause refer U-1(c)(2)(i). For this diamater the Code would be exempt.

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