There are two types of liquefied gas cylinders used by the public: "screw-type" cylinders, where the protective collar is attached to the body with screws; and "welded" cylinders, where the collar is electrically welded to the body. National regulations explicitly state that the safe service life of a liquefied gas cylinder is 15 years, with mandatory inspections required every four years. Because "screw-type" cylinders lack permanent markings on the body, the state explicitly banned their production starting in September 1996. Consequently, even the very last batch of "screw-type" cylinders produced has now exceeded the 15-year limit and must be mandatorily scrapped.
The standard service life of a liquefied gas cylinder is generally 15 years. Within the first 12 years after leaving the factory, inspections are required every four years, and the cylinder must be scrapped once it exceeds 15 years of age. Of course, any cylinder deemed unfit for continued use-for whatever reason-must also be taken out of service; never jeopardize your family's safety through negligence.