Cylinder Valve Standards, Replacement Periods and Repair
Mar 14, 2022| Cylinder Valve Standards, Replacement Periods and Repair
Valves are fitted into a threaded bung, or boss, in the top of LPG cylinders. Sealants, or PTFE tape, are normally used to achieve a gas tight condition. The over use of PTFE tape can cause stress on the brass valve through over tightening. This is the reason why internal standards of some companies prohibit the use of PTFE.
The degree of accuracy of the matching threads of valve and bung is critical for a gas tight fit. Some cylinder valve manufacturers' deal with this by manufacturing and supplying the bung to the cylinder manufacturer for the initial build to ensure a good match with the valve.
This may not be the case when valves from other manufacturers are used to replace the original valve.
Most/all countries replace, rather than repair, valves if they become damage or are replaced during the requalification procedure.
This avoids confusion and potential liability in the event of an incident with the valve in service.
If an incident occurs with the valve, and the repairing of valves is common, the question will inevitably be asked by the valve manufacturer; 'has the valve been repaired or was it supplied by us like that...?'
This eliminates the risk of cylinders being re-used. Hand wheel valve fitted to a cylinder together with a plastic seal to protect the valve thread and prevent accidental opening
Not all countries replace the valve when the cylinder is requalified. Some countries re-use the valve if it is still fit for purpose, others have a mandatory replacement policy on requalification.
Mandatory valve replacement at the requalification date increases the cost but might achieve savings later if the cylinder valve has to be replaced before the next requalification period is due and the cylinder has to be withdrawn prematurely.
In Japan the requalification for the cylinder is 5 years whereas the valve is replaced every 6 years. This frequently results in earlier valve replacement at the cylinder requalification time.
LPG Cylinder propane butane cooking gas energy