Propane tank inspection: three different tanks, three different rules

Propane tank inspection is one of the most searched phrases in this whole category, and one of the least precise. A twenty pound grill cylinder, a buried tank feeding a house and a bulk vessel at a plant are all propane tanks. They are built to different codes, owned by different people and inspected by different parties. The first useful step is to know which one you have.

Portable cylinders: the date on the collar

Small portable cylinders are built to Department of Transportation specifications. They are not inspected on a schedule by the owner. They are requalified, and the date that governs requalification is stamped on the collar. A filler is expected to check that date before filling. A cylinder past its requalification date is normally refused until it has been requalified or exchanged. The details of reading those marks are covered in the article on the collar stamp later in this series.

Residential tanks: usually the supplier’s tank

The larger tanks that sit beside a house or are buried in the yard are built to the ASME pressure vessel code. In many cases the propane supplier owns the tank and leases it to the homeowner, which matters: the owner of the tank is the party responsible for its condition, and the supplier is the one who inspects it at installation and at delivery. A leak check is typically performed when service is interrupted and restarted. If you own the tank outright, that responsibility moves to you.

Bulk and industrial vessels: the state decides

At industrial scale, propane storage falls under the fire code, under NFPA 58 as adopted in your state, and in many states under a pressure vessel inspection program. Which authority inspects, how often and with which credentials is set at state level, and it varies. The first question to ask is not which inspector to hire, but which program your installation falls under. The overview in who inspects what applies here too.

What an inspection of a propane tank looks at

Whatever the size, the same families of checks come back: the condition of the shell and its coating, corrosion at supports and at ground contact, the state of the relief valve and its discharge, the regulator and the piping, the gauge, and leaks at every connection. A buried tank adds the question of cathodic protection, the system that keeps a steel tank from corroding in soil.

Why the search volume is so high

The query peaks around three situations: a cylinder refused at a refill station, a home sale where the buyer asks about the tank, and a new owner who finds a tank on the property and does not know whose it is. Each one has a different answer, and none of them is answered by a generic inspection checklist. Knowing which situation you are in saves most of the confusion.

Where this site stops

This site covers steel storage tanks, mostly atmospheric tanks inspected to API 653 and STI SP001. Propane vessels are pressure vessels with their own codes. What carries over is the method: identify the code the tank was built to, the owner, and the program that governs it, then check that whoever inspects it is qualified for that program. How to verify an inspector describes that last step.

What to ask before anyone comes out

Ask who owns the tank, what code it was built to, and under which rule the inspection is being done. Ask what the inspection will cover and what the report will contain. A clear scope written before the visit is worth more than a long report written after it, because it is the only way to know what the report leaves out.

If the answers to those three questions are not clear, the inspection that follows is unlikely to be either. A supplier, an insurer and a state inspector can all look at the same tank and reach conclusions that do not conflict, because each one is checking a different thing. Knowing which of them you are dealing with is what turns a visit into an answer.