Gas tank replacement?

[Coopspeed]

I read while doing research on a possible purchase that the gas tank needs to be replaced at 100,000 miles or the date on the tank.

Is that a good idea or mandatory? Is it enforced? By who?

How much would a new tank for a 2002 Cavalier cost?

Thanks

Jim

[cngmike]

Re: Gas tank replacement?

The repalcement of CNG cylenders are on a 15 years. with visual in vehical inspections every 3 years or 36,000 miles. new tanks are rated at 20 years.

[kameron13462]

Re: Gas tank replacement?

I have to ask - why 15 years? Corrosion? Metal fatigue? Gas tank manufacturer needs a new pair of shoes?

[Coopspeed]

Re: Gas tank replacement?

So there is no requirement based on mileage?

I read that at 100,000 miles a tank is done.

That is false?

Jim

[Highmarker]

Re: Gas tank replacement?

All tanks are certified per NGV2-2000 specification. This specification mandates a cylinder life of 20 years. An important note is that all OEM vehicles (Ford F-150, Chevy Cavalier, Ford Contour) have tanks that were certified per NGV2-1998 specification. This specification mandates a cylinder life of 15 years. There is no requirement based on mileage (only the visual inspection that cngmike talked about).
To understand the reason why they put a expiration date on the cylinders you have to understand where composite overwrapped pressure vessels have came from over the past 40 years. Even self-contained breathing appratus (SCBA) tanks have an expiration date on them after 15 years (per DOT-CFFC). These tanks have to be hydrostatic proof tested every 3 to 5 years (CNG tanks do not). Most pressure vessel specifications are spin-offs of the military specification. The life of a tank is based on the pressurization cycle testing of the cylinder. Each CNG cylinder design has to pass 11,250 pressure cycles. Do the math, that is just over 560 cycles a year for 20 years.

[onefasteg]

Re: Gas tank replacement?

All tanks are certified per NGV2-2000 specification. This specification mandates a cylinder life of 20 years. An important note is that all OEM vehicles (Ford F-150, Chevy Cavalier, Ford Contour) have tanks that were certified per NGV2-1998 specification. This specification mandates a cylinder life of 15 years. There is no requirement based on mileage (only the visual inspection that cngmike talked about).
To understand the reason why they put a expiration date on the cylinders you have to understand where composite overwrapped pressure vessels have came from over the past 40 years. Even self-contained breathing appratus (SCBA) tanks have an expiration date on them after 15 years (per DOT-CFFC). These tanks have to be hydrostatic proof tested every 3 to 5 years (CNG tanks do not). Most pressure vessel specifications are spin-offs of the military specification. The life of a tank is based on the pressurization cycle testing of the cylinder. Each CNG cylinder design has to pass 11,250 pressure cycles. Do the math, that is just over 560 cycles a year for 20 years.

Like the post above, I am not understanding. E.G. a cars piston does this X amount of times in a cylinder wall (made of aluminum), rapid compression and decompression, cooling and heating. In X amount of years they expire too?

To me its just a number given by a test, not when it actually will or if it will expire.

The coating of the tank is suppose to stop micro cracks from appearing, and the wall thickness of this tank is pretty beefy, what would cause it to fail in X years.

[cowboy]

Re: Gas tank replacement?

it probley wont but you sure dont want to be around if it would fail it is a safe than sorry thing and there have been some fail if the car piston fails it makes a loud bad noise oil gos everywhere and you have to walk home if a cng tank fails it makes a much louder bad noise and you probley wont do anything again.

[Lakewood90712]

Re: Gas tank replacement?

Onefasteg,

If you have scientific data to back up your position , you should submit it to the U.S. D.O.T. , and let them know they should ammend the regulations on NGV Fuel cylinders.

in the mean time, check this thread http://cngchat.com/forum/showthread....kidding-right/ It's an lot fresher than bumping a 2007 thread , and pretty well beats the subject to death.

This thread closed.