CNG Cylinder (tank) inspection

[Gaz Guy]

How many of you are aware of the Federally mandated CNG Cylinder (tank) inspection requirements of NGV2-2000 and FMVSS 304?
Every 3 years or 36,000 miles, whichever comes first. Did the folks you bought your vehicle from happen to mention this?

[echamberlain]

Re: CNG Cylinder (tank) inspection

If your vehicle was manufactured after 1996, the CNG tank external visual inspections should be listed in your vehicle maintenance schedule.

Ford's TSB 05-5-6 has more information about the tank inspections.

[sixpak]

Re: CNG Cylinder (tank) inspection

How many of you are aware of the Federally mandated CNG Cylinder (tank) inspection requirements of NGV2-2000 and FMVSS 304?
Every 3 years or 36,000 miles, whichever comes first. Did the folks you bought your vehicle from happen to mention this?

It was in the manual for my GX. I just paid Norm Reeves about $148 and it seemed a little high.

[malibu]

Re: CNG Cylinder (tank) inspection

How much does it cost to replace if it does not pass inspection?

[afvman]

Re: CNG Cylinder (tank) inspection

Depends...

Type 1 (all steel/aluminum) cylinders in my van cost $200 ea. Type 4 (all composite) can go up to $1000-1500.

Each (Type 1, 2, 3 and 4) have advantages and disadvantages. It's interesting that as the number/type goes up, so does the price.

afvman

[Surfdancer]

Re: CNG Cylinder (tank) inspection

Silly question, but if one ignores the requirement to have their cylinders inspected (or runs them beyond their life expiration date), AND an event occured AND the owner survives the event, would they be liable for their neglect?

It would seem to me that these records would be at the top of the list if / when an insurance company or some lawyer became involved in an incident investigation.

I shut down our company vehicles when I learned the tank inspections were overdue. I had people very upset, but I could not take a chance having perfectly safe, yet uninspected, vehicled on the road. Fortunately, I was able to get the cylinders inspected in short order (not easy to do in a rural area on the East coast), and all issues were resolved.

[afvman]

Re: CNG Cylinder (tank) inspection

Gaz Guy et al,

The cylinder inspection agency is currently CSA-America (the old AGA Labs) in Cleveland, OH. They've been working on a whole new exam and training program for inspectors. It's being released as we speak.

They're the best bet for qualified cylinder inspections. See:

http://www.csa-america.org/advisory_services/cng_certification/

If I can help, let me know.

afvman/Bill
Lancaster, OH

[altfuelsguy]

Re: CNG Cylinder (tank) inspection

Depends...

Type 1 (all steel/aluminum) cylinders in my van cost $200 ea. Type 4 (all composite) can go up to $1000-1500.

Each (Type 1, 2, 3 and 4) have advantages and disadvantages. It's interesting that as the number/type goes up, so does the price.

afvman

Where can I get type 1 tanks?
I'm in CA.
What is good mfg. to look for.
thanks.

[johnnjerri]

Re: CNG Cylinder (tank) inspection

Can anyone tell me what the service life is on the tank in a new Honda 09 GX? Is it 15 years from manufacture date or??
Thanks!!

[snakeskinner]

Re: CNG Cylinder (tank) inspection

Class 1 is an all Steel or Aluminum tank, Class 2 is a Hoop wrapped steel or aluminum tank which means the center is wrapped in composite and the ends are exposed. Class 3 is aluminum or steel and completely wrapped in composite. class 4 is a total composite tank. Prices will vary depending on material, size, manufacturer and quality. I have heard of some very poor quality tanks available overseas (not sure they have been imported to the US) that are having high failure rates. We are installing Lincoln Composite Class 4 tanks in the trucks we are building. I believe they are a 12-15 gallon equivelant tank and are much more expensive than a lower class tank. I have not personally priced them myself but I have heard they can cost upwards of 6-7 thousand for a high quality class 4 of this size. Of course the smaller tanks wouldn't cost as much.

Regulations will vary from state to state. Oklahoma requires anyone that touches a CNG system to be state certified. The NGV 2 tanks typically are a 15 year lifespan although the latest tanks we received from Lincoln are 20 year tanks. I have no idea what the new honda is but it should be listed on a label nearby the filler or under the hood (or both).

If you don't have your tank inspected every 3yrs/36k miles, it likely depends on your state laws. Oklahoma does not have a policing agency so it's up to the owner to obey the regulations. Granted, there is nobody going to stop someone because they don't have the tank inspected but do you really want that liability? In the case that you might get in an accident, if a police officer were educated in CNG and noticed your tank was out of date or hadn't been inspected, your state may have fines or worse. Every issue I've heard from CNG was due to improper handling of the tank. You're dealing with 3600 psi in most cases, not worth the gamble. The "tank inspection" should actually include a total inspection of the system. From what I have seen, the industry standard to perform this thorough inspection is 3 hours.

Kyle

[sjseng]

Re: CNG Cylinder (tank) inspection

If it is an internal tank inspection, does the vehicle need to come in with a nearly empty tank? Does the inspecting agency (say Honda) fill your tank back up if you happen to bring it in nearly full? How does that work.

Thanks

[karlhafen]

Re: CNG Cylinder (tank) inspection

Tanks are only visually inspected on the outside. The only time you would drain a good tank would be to replace a pressure relief device or tank valve

[sjseng]

Re: CNG Cylinder (tank) inspection

Thank you.

[cowboy]

Re: CNG Cylinder (tank) inspection

I dont understand this is not safety all it takes is a little water presto you have rust inside weakning the tank not checking the inside like going to the canser doctor and not looking up your butt just stand there with your clothes on my you look good today as your insides are ate up I dont do tank certs but I own a scope and do check the inside of the tanks I buy before I send them off for hydro saves cash and time I have never had a tank fail hydro that looked good inside now im am dealing with strait steel not on road just storage still makes sense to check all tanks inside no mater what kind as and is not hard to do I bought my scope for229.oo with light as a tank failure is a very bad thing as i saw a air compresser tank set at 150 psi blow a cinder block wall down in a friends shop lucky no one was there when it happend cant fatham what 3600 psi whould do blow down a city block or two ?

[Franz]

Re: CNG Cylinder (tank) inspection

Cowboy, I have had two cylinders fail while I was there. Both were new installs, one with a CNG brand, the other a PST cylinder. Both split mid way between the straps. Neither of them showed any signs of damage that might indicate failure, and one wouldnt expect a failure on a new cylinder with a factory installed service valve.

Both splits were about 4 inches long at about 3000 psig pressure, on the first full fill, after a series of step up preliminary fills with leak checks. The tanks did not rupture full open, just one loud snap then VERY loud hissing.

In the cases where the tank was weakened by external impact or corrosion, a decompressive release can be exciting. These well publicized cases:
The Super Shuttle van recently;
Crown Plumbing in House (bent a chassis up about 6 inches)
Two GMC Sierra trucks of the early 90's;

One primary reason for internal failure on CNG tanks is a product found in natural gas if it is not fully scrubbed at the gas plant, Sulfur Dioxide. If any moisture is present in the fuel, it will react with the SO2 and cause a corrosion line which can weaken a type 1, type 2 or a type 3 cylinder. A type 4 cylinder is not as effected.

The method of hydrostatically testing cylinders to two times their maximum working pressure is required by law but technically archaic, plus there can be an argument that this process can initiate a weakening effect as well. There are plenty of non destructive processes that are gaining recognition in the industry. Some states already recognize acoustical testing for example.

Franz