Flexible double containment piping system for underground storage tank

摘要

A double underground piping system conveys fluid from the outlet port of a pump (37) disposed atop an underground storage tank (13) to the inlet port of an above-ground dispenser (35) of liquid, e.g. gasoline, and 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 primary pipe (22) and a secondary pipe (19) surrounding the primary pipe so as to define an annular space (27) within which any leakage from the primary pipe is totally contained. The connection is accomplished by pump and dispenser couplings each including an inner pipe (23), an outer piping adapter (15), a male threaded coupling (20) and compression fittings (17, 18). The piping sytem may be used in a gasoline station with multiple tanks and multiple dispensers, using connections that are installed in chambers (12) that also provide containment.