# US 5,590,981 A · Double-containment underground piping system

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- Number: US 5,590,981 A
- Document ID: US5590981A
- Status: Granted
- Kind: A
- Application number: 08/469,652
- Filed: 1995-06-06
- Granted: 1997-01-07
- Earliest claimed: 1988-12-20
- Assignees: Intelpro Corporation
- Inventors: Keith J. Osborne
- Web page: https://patentgrep.com/patent/US5590981A

## CPC

- F16L 39/02: for hoses
- B67D 7/04: for transferring fuels, lubricants or mixed fuels and lubricants
- B67D 7/3209: {relating to spillage or leakage, e.g. spill containments, leak detection (leak detectors for underground fuel dispensing systems G01M3/2892)}
- F16L 39/005: {for concentric pipes}
- G01M 3/04: by detecting the presence of fluid at the leakage point
- F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- B67D: DISPENSING, DELIVERING OR TRANSFERRING LIQUIDS, NOT OTHERWISE PROVIDED FOR (cleaning pipes or tubes or systems of pipes or tubes B08B9/02; emptying or filling of bottles, jars, cans, casks, barrels, or similar containers, not otherwise provided for B67C; water supply E03; pipe systems F17D; domestic hot-water supply systems F24D; measuring volume, volume flow, mass flow or liquid level, metering by volume G01F; coin-freed or like apparatus G07F)
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## 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.

## Claims

### Claim 1

A secondarily contained piping system comprising:
(a) a flexible inner supply pipe;
(b) an outer secondary containment pipe;
(c) a first underground access chamber;
(d) a second underground access chamber spaced from the first underground access chamber;
(e) said flexible inner supply pipe positioned to provide a path of fluid communication between said first underground access chamber and said second underground access chamber;
(f) said flexible inner supply pipe having an exterior surface;
(g) said flexible inner supply pipe further having a first end and a second end;
(h) said secondary containment pipe surrounding at least a portion of the exterior surface of said inner supply pipe;
(i) a fluid source connected at the first end of the flexible inner supply pipe;
(j) a fluid outlet connected at the second end of the flexible inner supply pipe;
(k) a first coupling connecting the flexible inner supply pipe to the fluid source, the first coupling being disposed within the first underground access chamber; and
(l) a second coupling connecting the flexible inner supply pipe to the fluid outlet, the second coupling being disposed within the second underground access chamber.

### Claim 2

A secondarily contained fluid distribution system for supplying fuel to at least one fuel dispenser comprising:
(a) a fuel dispensing unit;
(b) a flexible inner fuel supply pipe;
(c) an underground outer secondary containment pipe;
(d) first and second access chambers, said first access chamber being associated with said fuel dispensing unit, said second access chamber being spaced from the first access chamber;
(e) said flexible inner fuel supply pipe positioned to provide a path of fluid communication between said first and said second access chambers;
(f) said flexible inner fuel supply pipe having an exterior surface;
(g) said flexible inner fuel supply pipe further having a first end and a second end;
(h) said secondary containment pipe surrounding at least a portion of the exterior surface of said inner supply pipe;
(i) a fuel source connector at the first end of the flexible inner fuel supply pipe;
(j) a fluid outlet at the second end of the flexible inner fuel supply pipe which is connected to said fuel dispensing unit;
(k) a first coupling connecting the flexible inner fuel supply pipe to the fuel source connector, the first coupling being disposed within the first spaced access chamber; and
(l) a second coupling connecting the flexible inner fuel supply pipe to the fluid outlet, the second coupling being disposed within the second spaced access chamber.

### Claim 3 (depends on 1)

The secondarily contained piping system as defined in claim 1 further comprising:
a first fitting associated with the first coupling, the first fitting being disposed within the first access chamber; and
a second fitting associated with the second coupling, the second fitting being disposed within the second access chamber.

### Claim 4 (depends on 1)

The secondarily contained piping system as defined in claim 1 wherein the flexible inner supply pipe is segmented and wherein the piping system further comprises:
a plurality of intermediate couplings connecting segmented portions of the flexible inner supply pipe; and
additional underground access chambers, as necessary, each of said intermediate couplings being disposed within one of the underground access chambers.

### Claim 5 (depends on 4)

The secondarily contained piping system as defined in claim 4 further comprising a plurality of intermediate fittings, each intermediate fitting being disposed within one of the underground access chambers.

### Claim 6 (depends on 2)

The secondarily contained fuel distribution system as defined in claim 2 further comprising:
a first fitting associated with the first coupling, the first fitting being disposed within the first access chamber; and
a second fitting associated with the second coupling, the second fitting being disposed within the second access chamber.

### Claim 7 (depends on 2)

The secondarily contained fuel distribution system as defined in claim 2 wherein the flexible inner fuel supply pipe is segmented and wherein the fuel distribution system further comprises:
a plurality of intermediate couplings connecting segmented portions of the flexible inner fuel supply pipe; and
additional access chambers, as necessary, each of said intermediate couplings being disposed within one of the access chambers.

### Claim 8 (depends on 7)

The secondarily contained fuel distribution system as defined in claim 7 further comprising a plurality of intermediate fittings, each intermediate fitting being disposed within one of the access chambers.