GB2258735A - Leak testing device for a valve in a pipeline - Google Patents

Abstract

A leak testing apparatus (28) for an emergency shut-down valve (12) in a hydrocarbon pipeline (14) comprises two inflatable bags (50, 52) mounted an a shaft (34) and located within a can (30). The bags are inflated within the pipeline to seal the pipeline and one of the bags includes a hose (48) to sample the pressure between bag (52) and the valve. The can (30) is mounted an a ball valve (22) and inserted into the pipe via the valve. <IMAGE>

Description

LEAK TESTING APPARATUS The present invention relates to a leak testing apparatu For exampl.e the invention relates to leak testing apparatus for use in detecting leakage past valves in pipelines containing liquids or gases The present invention has particular reference to the leak testing of emergency shutdown valves which are nov mandatory in pipelines which both supply inflammable hydrocarbon materials for processing on oil and gas rigs and for the discharge of the processed oil or gas from such rigs.

Emergency shutdown valves are provided to ensure that if a fire should break out on an oil or gas rig the supply of unprocessed hydrocarbons from the oil or gas field and the processed oil or gas which has been pumped from the oil or gas rig can be isolated from the rig itself, thereby preventing the fire from being fed by unprocessed and, or processed hydrocarbons it is now also mandatory that the emergency shutdown valve are tested on a regular basis to ensure that the valve'.

operate to isolate the unprocessed and processed hydrocarbon@ from the oil or gas rig and that. the leakage of hydrocarbons past the emergency shutdown valve is within a pre-determined limit.

The present invention seeks to provide a leak testing apparatus which can be located in an oil or gas pipeline immediately adjacent an emergency shutdown valve in a convenient manner and which can be used safely and efficiently to test the leakage rate of hydrocarbons through the emergency shutdown valve r'ccordingly the present invention provides a leak testing apparatus comprising a housing, s. shaft extending through the housing, inflatable means mounted at one end of the shaft,, duct means extending from the inflatable means to the opposite end of the shaft and being connectable to inflation means the inflatable means being capable of being sealingly located in a pipeline adjacent a valve in the pipeline, a sarrpler duct extending from the inflatable means through said shaft the sampler duct being communicable with a space between the inflatable means and the valve in the pipeline The housing can comprise container having an open end and a closed end , the shaft extending through a seal in the closed end of the container The inflatable. means can comprise an pair of inflatable bags each bag being hingedly mounted to the shaft In a further arrangement, the bags can be f fixedly attached to an adaptor secured to one end of the shaft The duct means can comprise a pair- of hoses, one hose being connected to each bag and extending through the shaft and terminating at the opposite end of the shaft The sampler hose can extend from the end of the shaft remote from the inflatable bags passing through a connection in the wall of one of said bags and terminating at a wall of said bag, the said bag being that b adjacent the valve The sampler duct can be connected to a leak rate cha recorder, or any other suitable recording apparatus.

The valve can comprise an eflergency shut-down valve located in a hydrocarbon pipeline.

The invention further comprises a leak testing apparatu@ including access means comprising an opening in a pipeline wall located adjacent a valve, a nozzle secured to the pipeline over the opening and an access val.ve connected to the nozzle, the leak testing apparatus being connectable to the ace valve The invention further provides a method of leak testing a valve in a pipeline comprising the steps of inserting a deflated inflatable pipe sealing means into a pipeline adjacent the valve, inflating the inflatable sealing means to seal a space between the valve and the inflated sealing means and monitoring any leakage past the valve into the said space.

The inflatable sealing means can comprise a pair of inflatable bags and the method of testing a valve includes the steps of inflating both said bags and pressurising the space between the two bags and monitoring any leakage from said space The method further comprises the steps of deflating the inflatable sealing means and withdrawing the deflated sealing means from the pipe through the access means, closi n';; an access valve in t.he access means and disconnecting the leak testing apparatus from the access means The method further includes the step of applying a partial vacuum to the inflatable sealing means prior to withdrawing the sealing means into the access means The present invention will now be more particularly described with reference to the accompanying drawings in which Figs. 1 to 3 illustrate diagrammatically the steps 0 installing access apparatus for- one form of leak testing apparatus according to the present invention, Fig. 4 shows an elevation of one form of leak testing apparatus according to the present invention installed in position in a pipeline, Figs. 5 to 9 inclusive illustrate diagrammatically the steps of operating the leak testing apparatus illustrated in Fig. 4.

Fig. 10 illustrates diagrammatically the closure of the access apparatus with the leak testing apparatus illustrated in Wig, 4 removed and Fig 11 shows an alternative form of leak testing apparatus according to the present invention.

Referring to Figs. 1 to 3 inclusive a gas or oil pipaline 10 is connected between an oil or gas platform (not shown) and a gas or oil field (not shown). The pipeline 10 includes an emergency shutdown valve 12 connected on one side to a riser pipe 14 from the gas or- oil field and on the other side by pipe 16 which is connected to the oil or gas platform. The valve 12 can be for example a ball valve.

In this example the pipeline 10 is shown in the supply side to the oil or gas platform receiving cr-ude oil or gas from the oil or gas field. There is also a. similar emergency shutdown valve in the pipeline from the oil or gas field through which is pumped processed oil or gas so tat the pipe 16 could be carry a flow of processed oil or gas to be transmitted to a terminal through the valve 12 and the pipe 14.

In order for a leak testing apparatus according to the present invention which is illustrated in Fig. 4, to be inserted into the pipe 16 an access apparatus 18 is secured to the pipe 16 as illustrated in Figs. 2 and 3.

Referring to Figs. 1 to 3, the access apparatus IP is secured to the pipe 16 in the following manner-. The pipeline. 16 is initially vented to atmosphere after the emergency shutdown valve 12 has been closed. The pipeline 16 is monitored to detect any significant leakage of hydrocarbons through the closed valve 12. In the absence of any significant leakage vex of hydrocarbons through the valve 12, a T-nozzle 20 is welded to the pipe 16 as shown in Fig. 2.A ball valve 22 is sealingly bolted to the T-nozzle 20 and the ball valve has a blind flange 24. The T-nozzle 20 and ball valve 22 are pressure tested through the blind flange 24 in order to ensure the integrity of the joints between the T-nozzle 20 and the pipe 16, the connection of the ball valve 22 to the T-nozzle 20 and the connection of the blind flange 24 to the ball valve 22.

With the ball valve 22 closed the blind flange 24 is removed and a hot tapping machine 26 is secured to the ball valve 22.

The connection between the hot tapping machine 26 and that ball valve 22 is pressure tested in order to test the integrity ot the joint between the hot tapping machine and the ball valve The ball valve 22 is opened and the assembly of T-nozzle 20, ball valve 22 and hot tapping machine 26 is pressurised with nitrogen (N2). The hot tapping machine is of a conventional type. The machine 26 has a cutting head which extends through the ball valve and through the T-nozzle 20 in order to out an opening in the wall of the pipe 16 by a trepanning method.

The coupon of metal which is cut by the hot tapping machine 26 is removed through the T-nozzle and ball valve 22 and is retained by the hot tapping machine 26.

The ball valve 22 is closed and the hot tapping machine 26 complete with the metal coupon is removed from the ball valve 22.

Referring now particularly to Figs. 4 and 5 a leak testing apparatus 28 is secured to the ball valve 22.

The leak testing apparatus 28 comprises a can 30 which 15 open at its end 30A in connection with the ball valve 22 but is closed at its end 308 by a blind flange 32.

hollow sha.ft 34 extends through a gland 36 in the blind flange 32. The shaft has at its upper end 34R three pressure connections 38, 40 and 42 which are connected respectively to inflation hoses 44 and 46 and to a sampler hose 48 The hose 44 is connected to an inflatable bag 50, and the hose 46 is connected to a further inflatable bag 52.

Each of the bags 50 and 52 has an articulated arm 54 which is hinged to a centre boss 56 secured at one end of the shaft 34.

The sampler hose 48 extends through the bag 52 by means of a coupling 54 and has an open end 60 in communication with the space between the bag 52 and the emergency shutdown valve 12.

Referring to Fig. . 5 which illustrates the leak testing apparatus in the pre-installstion position with the bags 50 and 52 collapsed within the can 30. The ball valve 22 is opened and the hollow shaft 34 together with the ccllipsecl.

bags 50 and 52 is inserted through the ball valve until the shaft 34 bottoms on the pipe 16 . The bags 50 and 52 are inflated by supplying a pressurised medium such as nitrogen through the inlets 38 and 40. As the bags are inflated to a.

pre-determined pressure the bags automatically will push axially along the length of the pipe 16 and the hollow shaft 34 will be pushed through the can 30 centralising the boss 96.

As soon as the specified inflation pressure of the bags has been reached the supply of pressurising medium is closed off thereby holding the pressure of the medium within the inflatable bags 50 and 52 In order to test the efficacy of the seal between the bags' 50 and 52 and the pipeline 16 the space between the bags ic.

pressurised and the pressure within this space is tested using a pr-essure gauge 62 and valves ou each h side of the pressure gauge as shown in Fig. 7 Assuming the inflated bags 50 and 52 effectively seal t1-'e pipe 16 any leakage of hydrocarbon through the emergency shutdown valve 12 is sensed by a pressure in the sampler hose 48 which is indicated by a pressure gauge 63 and recorded by a chart recorder 64 or other suitable recording apparatus as shown in rig 8 Once the leck rate across the emergency shutdown valve 12 has been establ.ished the bags 50 and 52 are deflated by releasing the pressure supply and the deflated bags are withdrawn into the can 30 by withdrawing the shaft 34 through the gland 36.

In order to assist the deflation of the bags 50 and 52 partial vacuum can be applied to the connections 38 and 40, causing the bags 50 and 52 to collapse.

The bags 50 and 52 will rotate by means of their articulated arms on the boss 56 Once the bags 50 and 52 have been withdrawn into the can 30 the ball valve 22 is closed and the leak testing apparatus 28 is disconnected from the ball valve 22 backup ball valve 66 having a blind flange 68 is connected to the ball valve 22 and both ball valves 22 and 66 are maintained in the closed position in order to prevent any hydrocarbons leaking through the T-nozzle 20 when the pipeline 10 is flowing with hydrocarbons whether unprocesseo or processed Referring to Fig 11 there is shown leak testing apparatus 70 which is similar to the leak testing apparatus 28 described above, and the same references have been applied to corresponding components. In this arrangement the shaft 34 terminates in a sleeve 72 to which iS fitted a hollow adaptor 74. The adaptor 74 has two cuffs 76 and 78 and inflatable bags 80 and 82 are secured to th cuffs 76 and 78 respectively Sample hose 48 passes through the bag 80 ano terminates in the open end 60 The interior of the adaptor 74 is connected through the hollow shaft to a pressure source so that the bags can be inflated or deflate if necessary by applying a partial vac'uum The leak testing apparatus 70 functions in the same manner as described above with reference to Figs 4-10 Nn advantage of the apparatus 70 is that it. requires a less complex form of construction and only one pressurising supply line is required It will be appreciated that once the access apparatus 18 has been installed in a hydrocarbon pipeline a leak testing apparatus as described above and in accordance with the- present invention can be installed in position conveniently and operated to test efficiently any leakage of hydrocarbons through the. emergency shutdown valve Once testing has been completed the leak testing apparatus c?.n then be removed and used for testing the leakage across other emergency $shutdown $valves. The leak testing apparatus according to the present invention can also bet used in situations other than hydrocarbon pipe-lines in order to test the leakage past valve in other types of pipeline.

Claims (1)

1 n leak testing apparatus comprising a housing, a shaft extending through the housing, a shaft extending through the housing, inflatable means mounted at one end of the shaft, duct means extending from the inflatable means to the opposite end of the shaft and being connectable to inflation means, the inflatable means being capable of being sealingly located in a pipeline adjacent a valve in the pipeline, a sampler duct extending from the inflatable means through said shaft, the sampler hose being communicable with a space between the inflatable means and the valve in the pipeline 2 An apparatus as claimed in Claim 1 in which the housing comprises a container having an open end and a closed end, the shaft extending through a seal in the closed end of the container - 3 An apparatus as claimed in Claim 1 or Claim 2 in which the inflatable means comprises a pair of inflatable bags, each bag being hingedly mounted to the shaft 4 An apparatus as claimed in any one of the preceding claims in which the. duct means comprises a pair of hoses, one hose being connected to e.ac- bag and extending through the interior of the shaft t, and terminating at the opposite end of the shaft 5 An apparatus as claimed in Claim 1 or Claim 2 in which the inflatable means comprises a pair of inflatable bags fixedly attached to the shaft 6 An apparatus as claimed in Claim 3, Claim 4 or Claim

5 in which the sampler hose extends front the end of the shaft remote from the inflatable bags , through one of said bags S and terminates at a. wall of the said one of said bags, the said bag being that bag adjacent the.

valve.

An apparatus as claimed in Claim 6 in which the sampler hose is connected to a leak rate recording apparatus.

8 An apparatus as claimed in any one of the preceding claims in which the valve comprises an emergency shut- down valve in a hydrocarbon pipeline 9 y leak testing apparatus constructed and arranged for use and operation substantially as herein described and with reference to the accompanying drawings.

10 A leak testing apparatus as claimed in any one uf the preceding claims including access means comprising an opening in a pipeline wall located adjacent a valve, a nozzle secured to the pipeline over the opening and an access valve connected to the nozzle, the leak testing apparatus being connectable to the access valve.

11 A method of leak testing a valve in a pipeline comprising the steps of inserting a deflated inflatable pipe sealing means into a pipeline adjacent the valve, through access means, inflating the inflatable sealing means to seal a space between the valve and the inflated sealing means and monitoring any leakage past the valve into the said sace.

12 R method as claimed in Claim 11 in which the inflatable sealing means comprises a pair of inflatable bags and includes the steps of inflating koth bags. and pressurising the space between the said two bags and monitoring any leakage from said space.

13 n method as claimed in Claim 11 or Claim 12 in which the sealing means are deflated and withdrawn from the pipe through the access means, closing an ac'cess valve- in the. access means and disconnecting the leak testing apparatus from the access means 14 A method as claimed in Claim 13 in which a partial vacuum is applied to the inflatable sealing means prior to withdrawing the sealing means through the access means 15 A method of leak testing a valve substantially as herein described.