Leaks in CNG Pressure Lines

Good answer, you got my vote.

Swagelok or Parker instrumentation compression fittings perform well if used properly.

If you like life, do not use hardware store fitings.

I presume you have leaky tube fittings?? Did you prepare the tubing correctly,?? have you torqued the fittings to manufacturers specifications?? Have you trapped foreign material in the fitting seats.

If other problems specify where the leak is.

As one of the other members said to use Swagelok fittings. I concur. We use them exclusively in my plant. Torque them properly and be sure everything else (especially the CNG tanks) is bolted down tightly - if you have any movement it will tend to cause the connections to loosen up. Ed

The very nature of your question informs me your level of knowledge and expertise is not adequate to perform any maintenance or installation of CNG lines. IF you want to stay alive and not die in a CNG fire, find someone skilled and knowledgeable in the field to perform the work. It is not appropriate or proper for anyone on this forum to attempt to help fix this problem. Doing so, while well intended, will probably contribute to a serious fire and possible horrible death.

I agree completely with Keith, the proper routing and securing of these lines is essential to continued life, not only you but anyone else around when it goes off. Refer to problem to a professional installer. Modifying a motor vehicle looks like a simple thing, it is anything but, I have been doing just that for over 35 years and I learn something new almost every week. I do not do any compressed gas conversions on vehicles because I am not certified to do the work, I know how, but knowing how and being certified in the task are two different things.

A common problem seen with untrained people is the issue of over-torque and deformation on stainless steel fittings when they are re-installed by someone in the field. As others have said, you have to be properly trained and hold certification. Swagelok and other suppliers have courses and special tools to assist with assembly.

Too often, I have seen untrained users that apply too many turns on a Swagelok (or other) stainless steel fitting. The result is galled threads and a deformed nut / ferrel assembly. This is especially common when parts are loosened and then retightened. The re-tightening procedure is very different (less turns) than for a new part.

Other areas to watch are damaged face seal o-rings and possibly NPT threads (which use teflon). I am not sure what type of fitting you are talking about.

a useful link is... http://www.swagelok.com/fittings/tube_fittings/tube_fittings_training.htm

Please close all tank valves and keep the vehicle parked outside for safety. Get the right technical support from a properly trained technician. Don't try this yourself.

In my plant our practice is to NEVER REUSE a Swagelok. We replace it. Saving a few hundred or a couple of thousand dollars a year by reusing fittings is false economy considering the magnitude of damage that is possible. Destroying a multi million dollar plant or killing/injuring a person is not acceptable. Edmund