Flexible double-containment piping system for underground storage tanks

摘要

A double piping system connected between an underground storage tank and an above-ground liquid dispenser, e.g. gasoline, provides containment to prevent the pumped liquid from leaking from the underground piping system into the environment. The piping system can be tested or replaced from grade without excavating or breaking ground at the installed tank site. Particularly advantageous assembly and disassembly of the system is provided by a coupling that involves cooperation between a bayonet-type quick-disconnect coupling for the primary piping and a bellows for the secondary piping. The bellows retracts to provide access to the quick- disconnect fitting for replacement of the inner piping. When extended, the bellows is sealably connected with a containment piping coaxial with the primary piping, so as to provide an annular containment volume around the quick-disconnect coupling.