Fuel Tank Leak Testing

[natebott]

What are some test methods for leak testing fuel tanks. Our tanks are of a welded design, and I am looking for a method of testing them to find any leaks, including pinholes. Any input is greatly appreciated.

 

[FrenchCAD]

I would go with pressured air or water

Cyril Guichard
Defense Program Manager
Belgium

 

[MiketheEngineer]

I agree

 

[zekeman]

I would fill the tank with water and connect the tank to a pressurized air volume of say 1 cubic foot, pressurize to say 15 psig,attach a pressure gauge and watch the pressure fall. To verify the integrity, I would imagine you should have a very minimal loss of water, and consequently the pressure should hold over a long period. The amount of water loss can easily be calculated from the gas laws.
If water holds then you can be reassured that oil will hold since it has a greater viscosity.

 

[handleman]

Mass spec sniffer type tracer gas testing will find holes much smaller than bubble, air, water, or pressure decay will.

Can be done using either helium or hydrogen as tracer gas.

-handleman, CSWP (The new, easy test)

 

[GregLocock]

I'd use a box of matches and an apprentice.



Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[berkshire]

Why not use the time honoured method of dye check.
Paint the outside seams with developer and slosh the inside of the tank with penetrant.
B.E.

 

[NomLaser]

Depends...are you wanting to be UL Listed?

 

[FrenchCAD]

Finally I do prefer Greg's method

Cyril Guichard
Defense Program Manager
Belgium

 

[TIMMAAYY]

Check with Cincinnati Test in Cincinnati Ohio. They do this service for you. They also make some unique fittings for quick connect/disconnect of sealing the tanks for leak testing.

 

[berkshire]

Beware of expediency when doing leak checking.
A long time ago, a British aeroplane company used to fill aluminium fuel tanks for jet aircraft with kerosene for leak checking. When a leak was found, the pressure was dropped off the tank and a welder TIG welded the leak on the full tank.
This was done for several years until a workman forgot to relieve the pressure on the tank, the resulting explosion killed several people.
B.E.

 

[Ralph2]

In places I have worked we tested our fabricated tanks with low pressure air.. 15 PSI and a bubble soap solution (snoop). This included tanks built into sides of small ships / tug boats. If... you use helium as a gas to pressure the tank it will find smaller holes.

Good luck.
(bear in mind the total force on a surface when "only" 15 psi is acting on it.. A large unsuported tank could become "round")

 

[NomLaser]

A lot of the testing methods are described in specifications that you need to meet for the tank. For example a UL spec that we meet requires a 3psig test using shop air held over a specified length of time. Other UL specs require much more testing and higher pressures. Some even require a destructive test prior to production building. I would find out the requirement that you need for the tank construction and go from there.