so I found a tank seller on Ebay that states that CNG tanks can be recertified much like scuba tanks. His pictures learly show the expiration date. I sent him a message telling him that I thought tanks had to be rendered unusable once they expired. Here's his response. Comments as I'm now officially confused.
"No, that is a common myth. I talked with the sole remaining American engineer in Wisconsin after the company sold their tooling to a Korean company and was given insight into the history behind the original 15 year certification: SCUBA tanks have to be inspected and recertified much more often due to moisture in the compressed air. This is not really an issue in methane (natural gas) but the company and federal DOT wanted some time horizon to evaluate the blanket certification without individual tank reinspection and they decided on 15 years with a proviso for blanket extension WITHOUT individual tank reinspection depending upon the tanks' performance during the initial 15 year program. They never had a failure or problem with any of their tanks in use during the initial 15 years or beyond and met every criteria for a blanket extension of the original 15 year certification without examination of individual tanks. However, to receive that blanket extension requires the original manufacturer to submit the results and application for blanket extension to DOT. But the Korean company that bought the tooling has no interest in reducing demand for its product, so it is not submitting the paperwork. Should you feel safe without an examination of every individual tank? Sure, but that's a judgment call. In any case, there is NOTHING in the original DOT certification or proviso for blanket extension that prevents anyone from re-certifying their tanks with individual inspection. Please note that my tanks have quite a long lead time built in before any reinspection could be required, so my telling you this doesn't really help my auction (some folks who thought they might need to replace their tanks will decide to keep using them) but I want to be 100% honest. Please feel free to do your own research but the idea that tanks must be destroyed after 15 years is a myth."
Thanks,
Jim
"No, that is a common myth. I talked with the sole remaining American engineer in Wisconsin after the company sold their tooling to a Korean company and was given insight into the history behind the original 15 year certification: SCUBA tanks have to be inspected and recertified much more often due to moisture in the compressed air. This is not really an issue in methane (natural gas) but the company and federal DOT wanted some time horizon to evaluate the blanket certification without individual tank reinspection and they decided on 15 years with a proviso for blanket extension WITHOUT individual tank reinspection depending upon the tanks' performance during the initial 15 year program. They never had a failure or problem with any of their tanks in use during the initial 15 years or beyond and met every criteria for a blanket extension of the original 15 year certification without examination of individual tanks. However, to receive that blanket extension requires the original manufacturer to submit the results and application for blanket extension to DOT. But the Korean company that bought the tooling has no interest in reducing demand for its product, so it is not submitting the paperwork. Should you feel safe without an examination of every individual tank? Sure, but that's a judgment call. In any case, there is NOTHING in the original DOT certification or proviso for blanket extension that prevents anyone from re-certifying their tanks with individual inspection. Please note that my tanks have quite a long lead time built in before any reinspection could be required, so my telling you this doesn't really help my auction (some folks who thought they might need to replace their tanks will decide to keep using them) but I want to be 100% honest. Please feel free to do your own research but the idea that tanks must be destroyed after 15 years is a myth."
Thanks,
Jim
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