Pneumatic Test Pressure

Hydro and pneumo are not generally substitutable for each other. Codes on this vary by location, but sometimes the hydro test is 1.5 x rated pressure, and pneumo is 1.1 x rated pressure. Other jurisdictions make hydro = pneumo = 1.43 x rated.

Wasn't the vessel already hydro tested at the factory? If so, obtain the paperwork.

Do not carry out a pneumatic test without a hydraulic test having been carried out to a higher pressure beforehand. If the reason is not obvious, then do not carry out any tests until having received training.

Where is the location - the Gobi Desert?

if you test with gas (air) if it breaks = possible explosion.

If it breaks with water = a leak.

You can never test a vessel this, save very low pressure soap bubble tests for leaks, say less than 1 PSI.

5 Kgm /cm2 = about 60 psi. a vessel exploding at 60 psi can wreck a building

http://en.wikipedia.org/wiki/Hydrostatic_test

Are you saying that you can't do a pneumatic test on a vessel? If so, check out response #5.

I'm upset he beat me to it but there are provisions for pneumatic testing of pressure vessels.

Pressure Vessels are factory tested and a test certificate is issued along with the delivery of the vessel. After its installation during testing along with the associated piping tests will be carried out as per the ASME standards. Regular inspection and pressure testing of these vessels need to be carried out by a competent authority as per the local codes. Usually pressure rest is carried out app 1.5 times the design pressure.

• As per ASME BPVC, Section VIII-1,UG-99, the pressure vessels designed for internal pressure shall be subjected to a hydrostatic test pressure which at every point in the vessel is at least equal to 1.3 times the MAWP multiplied by the lowest ratio for the materials of which the vessel is constructed of the stress value S for the test temperature on the vessel to the stress value S for the design temperature.

P_h = 1.3 MAWP x (S _{at test temp.} / S _{at design temp.}), where, P_h = hydrostatic test pressure & MAWP = max. allowable working pressure

• And as per UG-100, a pneumatic test (with at least equal to 1.1 times the MAWP multiplied by the lowest ratio for the materials of which the vessel is constructed of the stress value S for the test temperature on the vessel to the stress value S for the design temperature) may be used in lieu of the standard hydrostatic test prescribed in UG-99 for vessels under certain conditions:

(1) that are so designed and/or supported that they cannot safely be filled with water;

(2) not readily dried, that are to be used in services where traces of the testing liquid cannot be tolerated and the parts of which have, where possible, been previously tested by hydrostatic pressure to the pressure required in UG-99.

P_n = 1.1 MAWP x (S _{at test temp.} / S _{at design temp.}), where, P_n = pneumatic test pressure

• Therefore, may be and by acceptance of AI, a pneumatic test can be done at your case in lieu of hydrostatic test.

Dear Friend,

Please indicate the size of the vessel.

If the WC of the vessel is small,if it is for normal Engg standard as a part of Safety,you can go ahead with Pnuematic rest.Convention:

1.5 times of the Operating presure.In your case 7.5 Kg/cm2 as gauge and Lock the vessel for 30 Minutes and see the presure drop.It will serve your purpose of comissioning the vessel with out any problem.

Factory inspector/Statutory requirement:

These vessels have to be tested according to local regulations or as per ASME Viii UFV per the code you have to carryout Hydraulic test 1.5 times of the Operating pressure and keep the same for 30 Minutes and see also pressure drop,and you have to put Metallic tag and have to clearly displace the test pressure/OP/Date and year.

You have to maintain the Record in a book where you are supposed keep all the

Stautory records .

With out bothering for all the formalities in the interest of safety you have to carry out The HT/PT as per the code.This is my advice taking in to long term view with Competant authorised person.

Regards

G.Surareddy

MO:9886530068

Dear Friend,

Air is compressible, so not allowed to use for pressure testing, if bursed it will be dangerouse.

SawadHkm

Please don't use a forum to decide what you do with this vessel. I see as many opinions here as facts.

Consult a pressure vessel engineer or an authorized inspector before making a decision.

Also, I wouldn't substitute air for water simply because it's inconvenient to get water. If moving the vessel prevents making it a bomb then I think it will be hard to justify a pneumatic test in place.