Verifying thickness of a pressure vessel

[jeap]

Hi all!

I'm in a big hurry trying to verify if a vessel could be adequated for a new service. The problem is as follows:

1.- The vessel is 36 in OD 10 feet high, pipe A-106 Gr. B.
2.-Bottom ellipsoidal 2:1 cap A-516 Gr. 70.
3.- Top Flange B.16 600#.
and should be used in the following conditions:

Fluid Natural Gas.
Corrosion allowable 1/16".
T= 30ºC.
Poperating = 1024 psig.

for my preliminary estimations, using ASME SEC VIII D1, it could not be adequated for the service. The problem is that this is the only vessel available. S (A-106) =17.1 ksi and S (A-516) 20 ksi.

Is there any code/criteria that can help to support/justify that vessel for de described service?
or

should I not use it?

Thanks in advance

 

[jeap]

Sorry I forgot to mention:

thickness for pipe = 1 inch.
thickness for cup = 1 inch.

It is possible justify this vessel by using maximum stress values other than recommended by standards?

thanks

 

[JStephen]

First question is whether it ought to meet ASME in the first place, and that will depend on the circumstances. Not all localities regulate pressure vessels. Watch fo OSHA regulations, building codes, or other similar requirements.

Will it check out without the corrosion allowance?

 

[jeap]

Results for circumferential stress from using:

MAWP = 1126 psi (110% Pop)

t=PR/(SE+0.4P) (Based on external radius)

t= 1.155 inch, which is greater than actual w/o using corrosion allowance, that's the problem.

For ellipsoidal cup: t=1.07 inch, which is closer but w/o corrosion...

If approved it's going to be installed at the discharge of a compression station. In fact it is a coalescer filter...

 

[jte]

Don't forget to include the mill tolerance in your calc's per UG-16(d)... For SA-106 that would be 7/8. If you have UT readings of actual thickness, you might be able to make a reasonable argument that this tolerance does not apply, but that'll be up to your AI to buy off on.

jt

 

[eliebl]

Was it a custom order pipe? ASME B36.10M does not list NPS 36 pipe as coinciding with a schedule number for 1".

 

[dcasto]

Some people would call the thing you described a frabricated piping system for use in a compressor station installed under B31.8 and not a pressure vessel. I've built many a pig launcher under this design specification and even some filters. look up the design calcs in B31.8 and I get the piping to have a 972 MAOP. You'll need to look and make sure there are not fillet welds on the piping and such and that all the welding passes 1104.

 

[JStephen]

There may be a Code Case that allows you to calculate a thinner head, although I don't know the details. (This was mentioned at a PV class).

 

[LSThill]

Reference CODE CASE 2260

 

[chicopee]

Check out the nameplate for the NB number and get a copy of the manufacturer's data sheet (based on the NB number) from NB for the information you seek.