LP Cylinder Requalification

The great pandemic has had long-lasting effects on all people worldwide, businesses, industries, and governments. Supply chain issues immediately come to mind, but government rule and law changes, it turns out, are yet another.

In the RV technician program, we continue to teach students that LP gas DOT cylinders must be re-qualified in the US 10 years from the manufacture date stamped on the valve guard and every five years after that.

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A student came to me and said it had been changed to 12 years…again. This is not the first time this has happened, as we have been back and forth on this over the last decade. As proof, he showed me a few websites that quoted 12-year re-qualification dates.

I went to the US Department of Transportation website to verify this, and their information indicated that it was still ten years old. When I showed this to the student, he said he had been told it had been changed, but he believed me.

Of course, little did he know he had just given a dog a bone.

I started researching with my colleagues at the RV Technical Institute, who had the same information as mine, and then I dug in.

I bounced around the LP gas industry websites to find an answer. Large gas suppliers were split, some saying 10, while propane cylinder exchange companies said 12.

Then, I found an article by Butane Propane News from December 21, 2020, that outlined the entire issue and claimed that the rule had been changed, effective November 30, 2020. Another article by LP Gas Magazine further verified the claim. “OK,” I thought, but this is not the end of the matter. I needed to see the law.

So, I turned to the Federal Register, 49 CFR 180.209(e), which details the requalification rules.

The difficulty in confirming this is that the rules for cylinders are not listed by “type” but by specification code. Fortunately, Manchester Tank came to the rescue with their DOT cylinder chart, including the design specs.

Per the Manchester chart, 20, 30, and 40-pound DOT cylinders have a spec of “4BA240”. The chart in the register says, “(e) Cylinders in non-corrosive gas service. A cylinder made in conformance with DOT Specifications 4B, 4BA, 4BW, or 4E protected externally by a suitable corrosion-resistant coating and used exclusively for non-corrosive gas that is commercially free from corroding components may be requalified by volumetric expansion testing every 12 years instead of every 5 years. As an alternative, the cylinder may be subjected to a proof pressure test at least two times the marked service pressure, but this latter type of test must be repeated every 10 years after expiration of the initial 12-year period. When subjected to a proof pressure test, as prescribed in CGA C–1 (IBR, see § 171.7 of this subchapter), the cylinder must be carefully examined under test pressure and removed from service if a leak or defect is found.

So, what is my conclusion? The initial recertification period for 4BA cylinders, as listed in the Federal Register, is 12 years. If requalified by volumetric testing, it will be due for recertification in another 12 years. Alternatively, a proof of pressure test can be performed with a 10-year requalification requirement after the initial 12-year requalification. Of course, enforcement of any requalification date is up to individual retailers. Some never look at the date, and some fill cylinders incorrectly and inappropriately. However, proper refilling procedures are always recommended, which include visually inspecting the cylinder and verifying the date.

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