600 PSI air pressure test

So, what happens when a submerged object catastrophically fails at 600 PSI of air?

Wouldn't that be like a bomb?

Yeah, you should lean heavily towards a hydrotest

http://cr4.globalspec.com/edit/newcomment?objectid=25943&objecttype=THREAD

https://www-training.llnl.gov/training/hc/5060/LiquidGas.html

http://www.worksafe.vic.gov.au/wps/wcm/connect/WorkSafe/HomeForms+and+Publications/Alerts/import_Pipeline+fails+under++air+pressure+test+-+Kills+worker

http://smad-ext.grc.nasa.gov/gso/manual/chapter_07.pdf (APPENDIX C)

Hello gdevine

The above replies are correct.

It is not generally realised just how much energy is stored in compressed gases, and at 600 PSI, any failure would be catastrophic, with almost any observer, plus the testing station and the building around, probably demolished.

All proper pressure tests are normally done hydro-statically, because if there is even a tiny leak, the pressure drops very quickly to safe levels, because liquids are essentially incompressible, (Remember to have a polycarbonate or similar screen for the testing engineer to view the test - this prevents receiving a sudden jet of water from any sudden leak, in the eye etc.).

Advise your boss, or the Company which wants the tests done, that it would be a breach of both common sense, and Safety Regulations in most Locations.

We don't want to read your obituary, in the near future.

Kind Regards....

Testing with compressed air is VERY dangerous. Ask any dive shop about the dangers of an air leak. There is a wide network of businesses that hydrostaticly test dive bottles, fire fighters' SCBA tanks, welding tanks and fire extinguishers that I can think of.

If you have to do it in house, can you seal the manifold and attach a compound pressure gauge to it. Then put the manifold inside a vacuum chamber and watch the gauge. If there is a leak in the manifold, the pressure gauge will go into a vacuum.

In this case, everyone is correct. Leak testing at 600 psi with gas, can be dangerous. But, if you need to locate small leaks, you may have no other choice. I suggest you obtain a copy of Nondestructive Testing Handbook Volume 1 Leak Testing published by American Society for Nondestructive Testing.

Don't get me wrong here - I am not advocating a pneumatic test - but,

If you still must proceed with it - I would suggest immersing the manifold, fairly deeply, before pressurizing. We still don't know yet what kind of volume you are talking about yet though. I suppose that the water would act as some form of barrier to a projectile - think of a bullet travelling through water - it loses energy rather quickly.

1. Hydraulically test to 1.5 times the operating pressure on water first!
2. Apply air pressure up to and not over the operating pressure, and spray the parts suspected to be leaking with water mixed with a little washing-up liquid. The leaks will show up as bubbles.
3. Fix the leaks.
4. Repeat 2 and 3 until all the leaks are gone.

Do not be tempted to skip step 1! There are too many forms to fill in to complete funeral arrangements these days....

If you must gas test and have taken all the other safety advice onboard e.g placing the component in a water filled pit in a safe area etc. then I suggest that you consider using nitrogen for the test media. The number of bottles or quads required will depend upon the volume of the test component, but one or all are manifolded together into a regulator which should have gauges indicating the pressure remaining in the bottle(s) and the regulated(test) pressure.

The pit should be monitored remotely using CCTV. A valve should be tee'd off the supply line (hose) for venting the gas post test - or in an emergency condition should the component fail! It is important that a test gauge is fitted as close to the test piece as possible and visible via the CCTV.

The pressure should be increased slowly in stages of e.g 50 psi and again depending upon the component size a settling period of a minimum of 5 minutes each pressure stage to watch for escaping bubbles. Note that air bubbles will escape naturally from the component if it has a compound structure which form air pockets, and these need to be allowed for.

AT the succesful completion of the test the vent valve should be opened. Watch for freezing and do not approach the pit until there is zero pressure shown on the pit test gauge.

The devil is in the details. It is good to advise that compressed gas can create a hazardous condition, however, the optimum leak test procedure is normally dictated by the test requirements. If you are attempting to pinpoint the location(s) of leaks in the order of 10exp-6 atmccHe/sec or smaller, you can't get adequate sensitivity with a fluid. This is because of the high viscosity of fluids compared to gas. After the required test sensitivity is specified, reasonable procedures can be recommended. For very fine leaks, a helium mass spectrometer may be required.

We work with valves for control of natural gas in automotive application. The leak test in accordance with specific standards is done with NGV @ 3600 PSI. We use excess flow valves for cut suddenly the source of pressure in case of quick lack of compression and a protection polycarbonate screen when the valves are submerge in water. The increase of pressure must be slow!

IF you use a small capacity high pressure pump, with shut off switch, pressure regulator, and blow out plug, with no reservoir to pump up the test items this will simplify everything and increase your safety factor in testing. As there will be little volume of air to decompress when a component fails, rather than leaks.

If this set up is not practical use the excess flow valves mention in post #11.

Soap bubble detection works a lot better than bubble tank, but do this first with low pressure air. If it matches your production requirements. It will be much safer at low pressure and the results will probably not be any different than at 600 psi.

In the water tank, make sure the tank is strong and the water can freely go someplace safe, away from the operator. The water tank will NOT contain an explosive discharge @ 600 psi. It must be designed to dissipate the energy safely.

If you use the pump idea, interlock the start switch with a couple of safety switches to be sure the operator is not short cutting safety, or use the same switches with the pressure release solenoid. If you need to protect the manifolds and fittings from shock loads use a fixed diameter orifice valve to bleed the pressure up slowly. If you need to test shock loads, you will need a reservoir in the air supply.

first you need someone to calulate to stored energy factor because at 600PSI and with the volume (?) it can be catastrophic. on the project i'm on now we are in the process of testing a 60" X 385' flare riser stack at only 55PSI and it calulates to 67 pounds of TNT stored energy. We will be closeing the project to preform the test. I would suggest a third party that specializes in this type of testing.