Abstract: A coaxial piping system connected between an underground pump and an above-ground liquid dispenser is used to provide containment of the pumped liquid from the underground piping system, preventing unintended release into the environment. A pair of coaxial pipes are removably connected to the underground pump at one end and to the dispenser at the other end using quick-disconnect fittings to allow for the replacement of the piping. A primary pipe for conveying gasoline or the like is surrounded by a secondary pipe, which provides containment in the event of leakage from the primary pipe. The piping system can be tested for leaks or replaced from grade without excavating at the installed tank site. A sensor in the annular space between the primary and secondary pipes may be used to detect leakage. A path may be provided for the gravity drainage of such leaks from the secondary pipe into a containment chamber, where the liquid may be detected and removed.

Abstract: A coaxial piping system connected between an underground pump and an above-ground liquid dispenser is used to provide containment of the pumped liquid from the underground piping system, preventing unintended release into the environment. A pair of coaxial pipes are removably connected to the underground pump at one end and to the dispenser at the other end using quick-disconnect fittings to allow for the replacement of the piping. A primary pipe for conveying gasoline or the like is surrounded by a secondary pipe, which provides containment in the event of leakage from the primary pipe. The piping system can be tested for leaks or replaced from grade without excavating at the installed tank site. A sensor in the annular space between the primary and secondary pipes may be used to detect leakage. A path may be provided for the gravity drainage of such leaks from the secondary pipe into a containment chamber, where the liquid may be detected and removed.

Abstract: A coaxial piping system connected between an underground pump and an above-ground liquid dispenser is used to provide containment of the pumped liquid from the underground piping system, preventing unintended release into the environment. A pair of coaxial pipes are removably connected to the underground pump at one end and to the dispenser at the other end using quick-disconnect fittings to allow for the replacement of the piping. A primary pipe for conveying gasoline or the like is surrounded by a secondary pipe, which provides containment in the event of leakage from the primary pipe. The piping system can be tested for leaks or replaced from grade without excavating at the installed tank site. A sensor in the annular space between the primary and secondary pipes may be used to detect leakage. A path may be provided for the gravity drainage of such leaks from the secondary pipe into a containment chamber, where the liquid may be detected and removed.

Abstract: A double piping system connected between an underground storage tank and the above ground liquid dispenser is used to provide containment of the pumped liquids 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. Also, disclosed is a method for detecting such leaks and for the gravity drainage of such leaks into a containment chamber.

Abstract: A coaxial piping system connected between an underground pump and an above-ground liquid dispenser is used to provide containment of the pumped liquid from the underground piping system, preventing unintended release into the environment. A pair of coaxial pipes are removably connected to the underground pump at one end and to the dispenser at the other end using quick-disconnect fittings to allow for the replacement of the piping. A primary pipe for conveying gasoline or the like is surrounded by a secondary pipe, which provides containment in the event of leakage from the primary pipe. The piping system can be tested for leaks or replaced from grade without excavating at the installed tank site. A sensor in the annular space between the primary and secondary pipes may be used to detect leakage. A path may be provided for the gravity drainage of such leaks from the secondary pipe into a containment chamber, where the liquid may be detected and removed.

Abstract: 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.

Abstract: An underground storage tank for fluids such as gasoline or chemicals is provided with L-shaped piping means for venting vapor pockets that would normally be trapped inside an inclined tank. The tank has a generally cylindrical top surface with one or two vent tubes secured inside the top of that surface, each tube extending from a point immediately adjacent a head wall to an upstand exiting through the manway cover. When a pair of such tubes and upstands is provided, vapor can be vented or discharged to the atmosphere, regardless of which way the tank is inclined. Such venting of trapped vapor prior to a hydrostatic test on an underground storage tank permits accurate determination of tank leakage and integrity. Existing tanks may be retrofitted with such venting means.