GB2265988A

GB2265988A - Testing of fuel tanks and pipework. Valves.

Info

Publication number: GB2265988A
Application number: GB9306893A
Authority: GB
Inventors: Barry C Risbridger
Original assignee: W&J Risbridger Ltd
Current assignee: W&J Risbridger Ltd
Priority date: 1992-04-01
Filing date: 1993-04-01
Publication date: 1993-10-13
Anticipated expiration: 2013-04-01
Also published as: GB2265988B; GB9306893D0

Abstract

A method of testing the integrity of fuel lines 2 connecting a fuel tank 1 with a fuel dispensing pump 5 and vent lines 7 from the tank is described. In the case of a suction line 2 from the tank to the pump, the method involves temporarily plugging the inlet port of an elbow connector 3 from the tank to the pump, isolating the pump 5 from the suction line 2 and pressure testing the line by connecting a pressure testing device to a sealable access point at the elbow 3 or at an underpump valve 6. The tank is pressure tested by closing the vent line 7 with a shut off valve 8, closing the suction line 2 either at the elbow 3 or at the underpump valve 6 and introducing a pressure fluid into the vent line. Also described are specific valve constructions for facilitating the testing of fuel lines and fuel tanks (Figs 4, 5, 6). In Fig 3D, a filter element (113) is mounted in the elbow, a support flange (132) being spring-urged against a seat (32). The filter is removed while the fuel lines are tested. <IMAGE>

Description

TESTING OF FUEL TANKS AND PIPE WORK This invention relates to a method of testing the integrity of fuel lines and underground fuel storage tanks. The invention also includes valve arrangements which facilitate the making of such tests.

At a filling station for dispensing petroleum fuels, one or more underground fuel tanks are frequently connected through pipe work running underground to emerge at a pump from which the fuel is dispensed, e.g. to vehicles. Normally, a fuel supply conduit from the tank rises into an inspection pit accessible by a manhole cover. Located within the pit is an angle check valve which connects the rising supply conduit with a suction pipe leading to the pump. Because the suction fuel line runs underground, often for considerable distances, there is a risk that fuel can leak into the ground from a pipe joint leak or fracture and cause pollution or risk of explosion before it can be detected.Recently, regulations have been proposed for the installation of underpump check valves which ensure that any fuel line leakage would cause the fuel to drain back into the tank, and not leak into the ground. Such an underpump valve should also have provision for an externally operated device to lift the valve poppet and allow the fuel to drain back into the storage tank without spillage. A major difficulty, however, arises with this kind of system. This is that when using conventional pipe fittings, it is difficult to test the integrity of the fuel suction line which runs from the angle check valve to the pump. An additional problem is that solid particles tend to be drawn up by the pump into the underpump valve when operating the pump.These particles may cause the valve to jam open and allow the line to drain back when the pump is switched off The pump must then be reprimed before it can be used again.

The present invention seeks to overcome the above difficulties and also provide a convenient method of testing the integrity of all fuel lines extended between the tank and the dispensing pump, for testing the tank itself and also lines from the tank to a venting stack or vapour recovery system.

According to one aspect of the present invention there is provided a method of testing the integrity of a fuel line connecting a fuel tank to a fuel dispensing pump, wherein an elbow connects the fuel tank via a suction line to the pump, said method comprising isolating the pump from the suction line, temporarily plugging the inlet port elbow leading to the tank, connecting a pressure testing device to the suction line via a sealable access point located at said elbow, or at an underpump valve and pressure testing the line using a pressure fluid.

The fuel tank itself may be separately tested using the same means to plug the inlet port of the elbow to the suction line and pressure testing the tank through another entry to the tank such as the vent pipeline. The vent pipeline may include a shut-off valve having an access port to which the portable pressure testing equipment can be connected. It may also be necessary when testing the integrity of the tank to close off the filling line, e.g.

by introducing a temporary plugging means into an elbow connection linking the filling line with the tank. The plugging means may be similar to that employed for closing off the inlet port of the elbow of the suction line. The integrity of the filling line is preferably tested by connecting the pressure testing equipment to a sealable access point at the filler cap end of the line.

Alternatively, access may be provided at the elbow linking the filling line to the tank.

Preferably, the means for temporarily closing off the inlet port to the elbow of the suction line and/or the offset filling line are remotely operated so that it is unnecessary for a man to enter the manhole above the connections for the underground fuel tank.

Preferably, the access points for connection to the pressure testing device at the underpump valve, the elbow connection on the suction line or on the offset filling line and the access point at the closure valves on the vent lines have the same connection fittings or have readily adaptable fittings Preferably, the elbow comprises the valve body of an angle check valve which is adapted for the purposes of this invention.

Various embodiments of the present invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a schematic view showing an underground fuel storage tank, the suction line connecting it to a petrol pump and the connections to a vent line and an offset fill line; Figures 2 and 2A are diagrammatic views of the portable pressure testing device; Figures 3, 3A, 3B and 3C are views of a test elbow and test plug for temporarily plugging the inlet port of the elbow; Figure 3D is a view of the test elbow of Figure 3 with a fll gr installed; Figure 3E shows a test elbow which is similar to that shown in Figure 3, intended to be used with a threaded test plug; Figure 3F shows a test plug suitable for use with the elbow of Figure 3E; Figure 3G shows a modification of the test elbow shown in Figure 3;; B Figures 4A#nd 4* are views of an elbow fitted with means for plugging the inlet port using a device which is remotely operable; Figures 5 and 5A show an underpump check valve fitted with a closure device for closing off the valve for testing the integrity of the suction line; and Figures 6 and 6A show a vent pipe shut off and test valve.

Referring to Figure 1 of the drawing, a fuel tank 1 is connected via a supply line 3a, an elbow 3 and suction line 2 to a dispensing pump 5. An underpump valve 6 is fitted with an externally-operable shut-off device enabling the line 3a to be isolated from the pump, and the lines 2 and 3a drained back into the tank. The underpump valve, of which a preferred embodiment is described later, may have a valve poppet which can be closed by a system of cams, levers, screws or other devices which are operated externally of the valve.

The elbow 3 may be the body of a check valve and the internal parts of which have been removed on fitting the underpump valve 6. The check valve body is utilised as shown in Figures 3 to 3F, or 4 and 4A, to accept a plug which can be used to temporarily close off the inlet port 10 of the elbow. The construction of these valves will be described in more detail later in this specification.

Referring further to Figure 1, the tank 1 is connected to a vent line 7, which can be closed of at a valve 8 Valve 8 includes a closable access port accessible to the vent line on the tank side of the vent line, so that it can be connected to a portable pressuretesting device so as to pressure-test the tank. The closure valve 8 is preferably operated by a security key or lock so that it cannot be closed by any unauthorised person.

As an alternative, the vent pipe 7 may be one of a number of vent pipes 7a, b and c, each connected to a storage tank, which are connected together to form a manifold which is connected to means for vapour recovery The manifolded vent lines may have individual closure valves or all be controlled together with a single closure valve The tank is also connected to an offset fill line 9 for replenishing the tank via an elbow 10.

Referring to Figures 2 and 2A, these show two views of the portable pressure testing device. The pressure testing device includes a pressure gauge 20, a connection point 21 for connecting the gauge to an access test point in the tank pipework. A nipple 22 for connection to a pressure fluid source such as a nitrogen bottle or a compressed air line and valves 23 and 24 for connecting the nitrogen bottle to the line to be tested and for connecting that line to the pressure gauge.

The test panel of the pressure-testing device also includes a pressure relief valve which is set to limit the test pressure applied to the tank or fuel pipework, e.g.

to about 1 barg in order to avoid applying excessive pressure to the system. The valves 23 and 24 allow the selected pressure to be applied to the line under test from the source of fluid under pressure and then the line to be isolated so that any leaks can be detected by a drop of pressure on the pressure gauge.

Referring to Figures 3 to 3C, these show a first embodiment of a test elbow which may be used in the suction line or filling line for the tank. The elbow comprises a body 120 which may the body of an existing angle check valve, the valve components of which have been removed on installation of the underpump valve. The body 120 has an inlet port 121 connected to the supply line 3a from the tank and an outlet port 122 for connection with the suction line 2. In normal use, the upper port 123 of the elbow is closed with a cap 124, which is threadably received in the port 23 and is sealed with an O-ring 25.

A stud 26 is received in a threaded boss 27 to seal the elbow.

In order to temporarily close off the port 121 in order to test the integrity of the suction line, a test plug 28 is provided for insertion into the test elbow.

Test plug 28 comprises a plunger portion 29 attached to a hexagonal cross-section rod, the rod 30 being sized so that it can pass freely through the threaded hole normally occupied by the sealing plug 26. The plunger portion 29 includes a land 31 and a projecting face 33. Projecting face 33 is dimensioned to enter the upper part of the port 21 with the land 31 engaging on flange 32 of the inlet port.

In order to plug the inlet port 121, cap 124 is removed together with the sealing plug 26. Test plug 28 is introduced into the body 120 so that land 31 seals on the top surface of flange 32. With the sealing plug 26 removed, cap 124 is reinstalled so that the cap slides over the rod 30, which projects through the top of the hole in the boss 27. Spring 34 engages in the recess 36 and the movement of screwing down the closure cap 24 causes the spring 34 to be compressed and the flange 31 pressed into contact with the flange 32, thereby sealing the line 3a and isolating the suction line 2 from the pump.

As mentioned above, the rod 30 is sized so that it does not completely fill the port within the boss 27.

This allows a fluid-tight connection to be made to the hole through the boss 27, thus allowing the line 2 to be tested for integrity through this outlet. Alternatively, a cap may be fitted over the port through the boss 27 in order to seal the connection and allow the test for the integrity of the line 2 to be made at the underpump valve or through a separate access point in the cap 124.

On completion of the test, the cap 124 is again unscrewed and the plug 28 removed. The projection of the stud 30 through the cap 24 is a visible reminder that the line is under test. The sealing plug 28 can be removed and put aside for use in the future or discarded. In one embodiment, a spring of about 10 to 11 p.s.i. is used.

The strength of the spring is selected so that it will yield if excessive pressure is applied to the tank during testing of the integrity of the tank to be described in detail later in this specification. As shown in Figure 3D, the spring 34 can be used to retain a filter 113 within the flange 32 during the normal use of the elbow, i.e. after a test has been completed and the suction line is in use. Figure 3D shows the filter in a raised position off the flange 32 but it will be appreciated that in use, the spring 34 will hold the flange 132 in firm contact with flange 32. The filter mesh openings are large enough to remove fine particles without significantly reducing flow to the pump. The conical shape of the filter gives an effective larger filter area.

Instead of employing a spring to maintain the sealing plug in engagement with the flange 32, it may in some cases be possible to use a threaded test plug where the flange is internally threaded or a thread can be conveniently formed on the flange (see Figures 3E and F).

A test plug with a corresponding shaped threaded can then be fitted using the hexagonal shaped stud to screw the test plug home (see Figure 3F).

Figure 3G shows a modification of the elbow of Figure 3. In Figure 3, the test plug 30 is held in place within the elbow by spring 34 and a sealing plug 26 is about to be fitted over the projecting stud 30. The cap 124 shown in Figure 3G is slightly modified in a way designed to prevent a check valve mechanism being refitted, It will be seen also that the stud 30 in this embodiment is circular in cross-section and there is a substantial gap between the stud and the hole through the cap 124.

In the embodiment of Figure 3G, the test cap 124 is screwed onto an upper flange 42, using bolts 40 and 41.

A ring e adaptor plate 43 is sandwiched between the cap 124 and the valve body 120. O-ring seals are provided between the adaptor ring, the upper flange 42 and the cap assembly 124 At least one of the securing bolts 40 is of a kind which shears off when subjected to a torque about a predetermined value. The twist-off torque value of bolts 40 is selected so that the bolts can be tightened sufficiently to compress the O-ring seal between the adaptor and the upper flange of the body 120, to produce a fluid-tight seal.The head of the bolt, such as 40, then twists off leaving a stub portion of a head 44 in a recess in the adaptor ring, and a threaded shank 45 in a corresponding threaded part of the flange 42. As a result, even if the bolts 41 are withdrawn, the adaptor ring 43 cannot be removed other than by a machining operation such as drilling. The arrangement described, therefore, prevents removal of the cap assembly 124 and adaptor and its replacement with a standard check valve and poppet, while enabling the modified elbow to be used to test the fuel line between the tank and the pump.

With sealing plug 26 in place, the suction line between the angle valve and the pump can be tested through an access port (not shown) in the cap 124, or at an access point in the underpump valve.

Referring to Figures 4A and 43, these show a modification of the angle valves shown in Figures 3 to 3G, which can be operated remotely. The valve body 120 may be the valve body of an existing check valve as in the previous embodiment, but in the case of the embodiment of Figures 4A and 4B, the test plug is permanently retained within the valve body. Cap assembly 124 has a central bore in which the plunger stud 30 is received, the plunger being biassed by spring 34 towards the flange 32 which constitutes a valve seat. Plunger 30 is held in its open position by a lever 140 to which it is pivotably attached at its upper end at 141.

Lever arm 140 has a rounded portion 142 in contact with the upper surface of the cap 124, the arrangement being such that by lifting the lever 140, e.g. with hook through hole 143, the lever will pivot upwardly and allow the plunger to close down onto seat 32 in a cam or togglelike action As shown in Figure 4A, the cap includes a tapped hole 144, which constitutes the access point for connection to the pressure testing device by screwing a suitable coupling into the hole. This tapped hole may be sealed with a plug so that, in the alternative, access to the suction line for testing can be made at the underpump valve.

Where an existing check valve body is employed, it may be desirable to employ an adaptor flange and twist-off bolts as described in connection with Figure 3G.

The underpump valve 6 is shown in detail in Figures 5 and fA. The underpump valve comprises a valve body 61 having a central bore, providing a valve seat 62. A poppet valve 63 is mounted within the bore and is biassed into a closed position by spring 64. In normal operation, suction applied by the petrol pump in the direction of the "flow" arrow raises the poppet against the action of the spring 64. Valve body 61 incorporates a valve lifter 65, which consists of a shaft rotatably received in the body 61 and having a forward end which projects beneath the poppet 63. The forward end of the shaft may be fitted with a pin at right angles to the shaft so that in a first position, it is inoperative and in a second position the pin lifts the poppet 63 off its seat against the action of the spring 64.In such second position, the suction line is then free to drain back into the tank. If necessary, in order to break any vacuum a port 66, which communicates with a chamber 67 beneath the valve 63, is opened.

The valve body 61 also includes a valve closer 68 which is used to shut off the supply line to the tank for testing purposes. Closer 68 comprises a rotatable spigot 69 on which a cylindrical closure member 70 is concentrically mounted. Thus, by turning the spigot into the position shown in Figure BA, valve 63 is shut off and the suction line isolated from the pump. Testing of the suction line for integrity can then be made through the port 66, which may incorporate a sealing cap which is removable for connection to the portable testing device.

As shown in Figure 5A, the centre of the poppet 63 has a raised, circular central portion 71. This ensures that when the cylindrical closure member 70 is rotated into contact with the poppet, a closure force is exerted on the poppet which is accurately aligned with the axis of the valve. This ensures secure sealing of the valve.

The necessary closure force can be applied using a screwdriver blade engageable with a slot 72 in the spigot 69. It may be more convenient to arrange for the valve closer 68, the valve lifter 65 and the test point connection or coupling 66 to be on the same face 73 of the underpump valve. Also, in order to prevent the valve closer being operated during the normal use of the pump, the head of the closer 68 may be shrouded with a sleeve having a cut-out which engages with a sealing cap for the coupling 66. This effectively locks the closer 68 until the sealing cap is removed from the coupling 66.

As indicated above, the vent pipe or pipes from the tank preferably incorporate a shut-off valve mounted above ground level. The shut-off valve incorporates or is used in conjunction with a sealable access point to the vent line This enables the pressure testing device to be connected to a vent pipe for testing the integrity of the tank. One example of a suitable form of construction of a shut-off valve incorporating a test access point is shown in Figures 6 and 6A.

Referring to these drawings, a shut-off valve comprises a valve body 81, arranged to be mounted in the vent pipe so that the arrow X indicates the top of the vent pipe Valve body 81 incorporates a valve seat 82.

A valve poppet 83 is mounted eccentrically on a hollow shaft 84 so that on rotation, the valve is movable towards or away from the valve seat 82. Because of eccentric movement of the shaft, the valve incorporates a wiping action which cleans the valve seat as it closes. For this reason, the washer 87 may be dome shaped. Shaft 84 includes a passage 85 which is connected externally with a self-sealing coupling 86 and internally with the valve body upstream of the valve seat. Thus, in the closing position in the valve, the testing apparatus can be connected to the coupling 86 by removing the sealing cap 88 and the integrity of the tank pressure-tested.

When testing the tank, the inlet port 121 of the suction line is first plugged and/or the poppet 63 of the underpump valve closed. If the inlet port 121 is plugged using à spring biassed test plug, the rating of the spring 34 (see Figure 3 etc.) in the elbow can be selected to lift at a predetermined pressure in order to provide a safety relief valve and thus prevent an excessively high testing pressure being inadvertently applied to the tank.

Claims

CLAIMS:

1. A method of testing the integrity of a fuel line connecting a fuel tank to a fuel dispensing pump wherein an elbow connects the fuel tank via a suction line to the pump, said method comprising isolating the pump from the suction line, temporarily plugging the inlet port of the elbow leading to the tank, connecting a portable pressure testing device to the line via a sealable access point in said elbow or in an underpump valve and pressure testing the line using an inert pressure fluid.

2. R method as claimed in claim 1 wherein the pressure testing device comprises a pressure gauge and valve means for connecting the gauge to the suction line and for connecting the gauge to a source of pressure fluid.

3. A method as claimed in claim 1 or 2 wherein the means for plugging the inlet port of the elbow is remotely operable.

4. A method as claimed in any one of the preceding claims wherein the access point in the underpump valve communicates with the suction line through the body of the underpump valve.

5. A method according to any one of the preceding claims wherein the suction line is closed off at the underpump valve by means of a closure device which extends through the wall of the body member and is movable between a first position in which the valve poppet is free to move and a second position in which the poppet is held in its closed position.

6. A method according to any one of the preceding claims in which the access point on said elbow, on the underpump valve and on an isolating valve on a vent pipe from the tank are similar, so that the pressure testing device can be connected to each access point.

7. An elbow connector for connecting a fuel tank to a suction line serving a fuel dispensing pump, said elbow having an inlet port having means for connection to a feed conduit from a fuel tank, a supply port having means for connection to the suction line, an access port adapted for receiving a closure member, a plug removably fitted within the elbow for temporarily sealing the inlet port, and a cap for closing the access port with said plug in place.

8. A connector according to claim 7 which includes a filter which can be introduced through the access port.

9. A connector according to claim 8 in which the filter is conical and is located and held in the elbow in the region of the inlet port.

10. A connector according to claim 7 wherein the plug is held in place by means of a spring acting between the cap and said plug.

11. An elbow connector for connecting a fuel tank to a fuel line serving a fuel dispensing pump, said elbow having an inlet port having means for connection to a feed conduit from a fuel tank, a supply port having means for connection to a suction line, an access port adapted for receiving a test plug, a filter element located and releasably held in the elbow in the region of said inlet port, said filter element being accessible through said access port for changing and/or cleaning the filter element.

12. An underpump valve for connecting the suction line from a fuel tank to a fuel dispensing pump, said valve having a body defining a seat and a poppet springbiased to close onto the seat and a closure device which extends through the wall of the body and is movable from outside the valve body between a first position in which the valve poppet is free to more in response to suction applied to the suction line and a second position in which the poppet is held in a closed position

13. An underpump valve as claimed in claim 12 which includes a sealable access point for communicating through the valve body with the suction line between said valve and the tank.

14. A valve as claimed in claim 12 or 13 wherein the closure device comprises a rod which is mounted eccentrically on an axis passing through the wall of the valve body, the rod extending across the valve poppet so that when the rod is rotated about the axis, it impinges on the valve poppet to hold it in the closed position.

15. A vent pipe shut off and test valve which comprises a valve poppet mounted on closure means within the vent pipe for movement towards and away from a valve seat, said closure means comprising a hollow shaft extending into the vent pipe and said poppet being mounted eccentrically on said shaft so that rotation of said shaft in one direction causes the poppet to be closed onto the seat and rotation in the opposite direction causes the poppet to be lifted off its seat, and a coupling connected to the shaft outside the vent pipe enabling a pressure fluid to be connected to the vent pipe through the shaft.