Leak test for weld cotainers.

Hi there,

Many years ago I worked for a shipyard where submarines were built; and LEAKS are an issue in this field!

The QC guys tested the quality of welding by means of special inks as well as with X-Rays.

You probably may get a lot of info about this issue searching for providers of materials / tooling used in the metal tube / pipe industry.

There are also companies that audit quality of welding

Good luck!

If you have an oil container of 55 gallons, like in tuna tins, to have internally with a polymer that seals the possible flights or dripping. Or put in a bag.

Leak testing is an art that can be real frustrating at times. Its especailly frustrating because you have openings to plug and that can be tough to eliminate any unwanted leaks in those areas.

The obvious method is pressurize the test article and monitor the pressure after its filled and see how fast it drops (known as pressure decay). Temperature can play havoc with the readings.

I personally like to measure the flow of air that has to go into the test article to maintain a test pressure. A good mass flowmeter works the best.

We're rebuilding a leak tester for the V10 blocks in the Chrysler Viper right now and its been a true pain for the engineer because all of the openings that have to be plugged. The entire head deck has to be sealed (no heads). And its using the pressure decay method.

Google search: Gas Taggants [chemical tag] depending upon the sensor you wish to scan with, a special [non poisonous] gas added into the air filling tested tank. hydrogen sulfide is used to reveal natural gas leaks. there are gasses which are UV detectable. even if very dilute. if you want concentrated gas for ease of detection, gas can pe pumped out and compressed for re use, losing only small amount per job you may even be able to use smoke, or dyed gas/air. its worth it to google search these items.

J Bo

Hi Dear,

Little bit confused whether problem with container material or with welding ? I wish to go with spec./composition check of both for material as well as of welding with design point of view.Study will also help upto which extent leak test is required.

Mentioned above was a method of using pressure decay to calculate the leak rate. Temperature changes woudl cause problems. I do not have experience of testing large vessels. It is best you contact leak test suppliers and get their opinion.

"Uson" are a market leader in the supply of pressure decay testers. Give them a call.

i just watched a episode of "how's it made" on the discovery channel last night where they were making automobile gas tanks...............they plugged the holes, pressurized them with a couple psi and then submerged them under water and watched for bubbles...

I worked for a long time making pressure vessels where leaks were always a problem. Fill the vessel with a 10% helium mixture to 110% operating pressure and use a mass spectrometer to sniff out any helium. we used 6.4 X10-6 for the setting on the mass spec, that would equate to 1.0 oz per year per leak or 1.5 oz. per year total vessel.

That should be acceptable.

use a pressure decay measurement. There are plenty of vendors that supply these devices. You just pressurize the vessel, and measure the pressure decay over a period of time. Good way to find a leak without the bubble test.

Also, if you want to get really involved with it, you could do helium test using a mass spectrometer to measure the amount of Helium leaking through your vessel. But then you need 20 grand and a source of helium.

-g

Look for local QC company or supplier with material leak or crack inspection. They spray a dye inside or outside the tank and the dye will sip through cracks and could be seen on opposite side.

Pineapple

Hello, Some friendly advice from Mirco Graenert Consulting Inc. Canada. Leak testing is most easily accomplished by adding air while the oil container is held under water. Of course of your container is very large you must have the equipment in place to move it, as well as having a pool sized water container, and a means to chain it down, since the air could make it boyant, pending on its weight of course. Let`s hope your container is small enough. Continous air bubbles will give away the smallest of leaks. I hope this helps. Mirco.

I'm interested in design & fabrication of pressure vessels in accordance with ASME Code. I need to know the following data:

1. Type of container material?

2. Container volume?

3. Container wall thickness?

4. Design pressure inside the container?

5. Welding procedure(s)?

6. Test pressure for hydrostatic and/or pneumatic?

7. Code or standard used in design, fabrication, inspection and testing?

You might try injecting a soapy foam into the tanks rather than air.

This does entail rinsing them out afterwards, but the leaks should
be easier and faster to see.

The company for which iam currently employed, has recently began producing a part that is robot welded. the unit must hold 25psi constantly, untill we, the fabricators are happy there will be no leaks. The shape is simple, that of a square but there is four 2in tubes running through and also two fluid escape/return holes. the water/bubble method is what we use. We have discovered its not the robot making mistakes, but the press operators incorrectly bending pieces, that causes our problems. Because they do not fit in our jigs exactly the same each time