Pipeline leak detection device

Abstract

The sphere of main pipelines used for hot water supply, specifically devices for electric surveillance control and water heat carrier leakage detection on atomic electric power station pipelines applied for operation of heat insulated pipes with a protective casing. Such pipeline leakage detection device uses a metal protective casing installed coaxially on a metal pipe with a radial clearance, where the casing performs as a joint of, for example, four arch shaped metal sheets bent across the pipe. Sheets straight line edges are joined by a dielectric washer, and sheets arch shaped edges are joined by a dielectric ring. Ring flanks have ring grooves on them for sheets arch shaped edges installation. Across each sheet arch shaped edge there are lamels shaped electric connectors installed in ring grooves for sheet arch shaped edge fixation. Electric connector terminals are fastened on the ring external surface and separately connected to each lamel.

Claims

1. A pipeline leakage detection device comprising a metal protective casing coaxially mounted on a metal pipe with a radial clearance, and a measurement instrument with electric conductors electrically connected to the metal pipe via electric contacts on the metal protective casing for measurement of electric resistance in radial clearance environment, such that to improve accuracy of localization of a pipeline leakage point the metal protective casing having separate arch shaped metal sheet segments along the circumference of the metal pipe, wherein straight line edges of the arch shaped metal sheet segments along a longitudinal axis of the metal pipe are connected with each other by a dielectric washer and arch shaped sheet edges of the segments along the circumference of the metal pipe are connected with each other by a dielectric ring, wherein the dielectric ring having a ring groove on its flank for mounting the arch shaped sheet edges installation with the electric contacts in it for each arch shaped sheet edge fixation and the electric contacts installed on the outer surface of the dielectric ring which are connected to each electric connector separately.

2. The pipeline leakage detection device according to claim 1, wherein the dielectric washer and ring formed an H-shaped cross-section.

3. The pipeline leakage detection device according to claim 1, wherein the radial clearance between metal pipe and metal protective casing filled up with thermal insulation material.

4. The pipeline leakage detection device according to claim 1, wherein the arch shaped sheet edges of metal sheets are bent by contour.

Description

(1) Invention is supported with several drawings, where:

(2) FIG. 1 presents a longitudinal view of the pipeline controlled segment connected to a measurement instrument;

(3) FIG. 2 presents the same case as FIG. 1, but its lateral view;

(4) FIG. 3 presents one segment of the protective casing section;

(5) FIG. 4 presents separable joint of the protective casing metal sheets straight line edges with dielectric washer;

(6) FIG. 5 presents separable joint of the protective casing metal sheets arch shaped edges with dielectric ring;

(7) FIG. 6 presents protective casing cylindrical compartment.

(8) FIG. 7 presents electric connector design with electric conductor handler in the protective casing dielectric ring;

(9) FIG. 8 presents electric cord handler design;

(10) Pipeline leakage detection device comprises a metal protective casing coaxially installed with a radial clearance 1 on the main metal pipe 2. Clearance 1 between the metal pipe 2 and the protective casing is filled up with thermal insulation 3. Protective casing is composed of a set of joined arch shaped metal sheets 4 bent across the pipe 2. In this case the pipe 2 is fringed with four arch shaped metal sheets 4 performed as separate segments, which comprise four sections of the protective casing. Straight line edges 5 and arch shaped edges 6 of these metal sheets 4 are bent along their contour. Arch shaped metal sheets 4 straight line edges 7 which are mounted along the pipe 2 are joined with each other by means of a straight line dielectric washer 8. Metal sheets 4 arch shaped edges 9 are joined with each other by means of a dielectric ring 10 which is installed on the pipe 2 concentrically. Four sections of the protective casing joined with each other comprise a cylindrical compartment that encloses the pipe 2. These cylindrical compartments that are successively joined with each other by means of arch shaped edges 9 and dielectric rings 10 make a protective casing body around the pipe 2. Washer 8 side walls 11 and 12 have straight line grooves 13 and 14 for installation of metal sheets 2 straight line bent edges 5 in these grooves 13 and 14. Ring 10 flanks 15 and 16 have ring grooves 17 and 18 for installation of metal sheets 4 arch shaped bent edges 6 in these ring grooves 17 and 18. Straight line grooves 13 and 14 in the washer 8 and ring 10 grooves 17 and 18 are H-shaped in cross-section. Each ring groove 17 and 18 across any metal sheet 2 arch shaped edge 9 has electric connectors installed for metal sheets 2 arch shaped bent edges 6 fixation. Electric connector is performed as a set of lamels 21 on parallel walls 19 and 20 of the ring grooves 17 and 18, which plates are bent in a U-shaped form. Lamels 21 have a pipe nut 23 installed on them from the side of the ring 10 external surface 22 which in its turn has a stud 24 screwed into it and a nut 26 with a washer 27 screwed on it from the other side 25 of the stud, which press it to a ring 10 external surface 22 and two lock nuts 28 and 29 with an electric terminal 30. In this case as the protective casing is performed as a joint of four sections, ring 10 external surface 22 has four pairs of electric terminals 30 evenly installed on the circle from the side of the arch shaped metal sheets. All rings 10 electric terminals 30 and metal pipe 2 terminal 31 are connected to the measurement instrument 33 by means of electric cords 32.

(11) Device operates the next way. Measurement instrument 33 is permanently launched and all arch shaped metal sheets 4 along with the pipe 2 are under small potential, e.g. three volts. Pipe 2 terminal 31 is connected to the negative pole and metal sheets 4 terminals 30 are connected to the positive pole of the measurement instrument 33 power supply. Pipelines ordinarily operate without any leakages. Under these conditions heat carrier temperature is higher than that of ambient environment which leads to extinction of any excessive moisture from thermal insulation 3. Within short period of time after start of heat carrier supply through the pipe 2 the value of humidity of thermal insulation 3 becomes constant and does not change any more. Electric resistance values which are dependent of thermal insulation 3 humidity and system electric capacity: metal sheet 4thermal insulation 3pipe 2 will also reach some constant values corresponding with the pipeline operation temperature. Measurement instrument 33 reveals that electric resistance and electric capacity between the pipe 2 and arch shaped metal sheets 4 around it are minimal.

(12) In case of an unlikely leakage existence, which can emerge because of the pipe 2 metal corrosion or defective weld, heat carrier spreads from the pipe 2 into a thermal insulation 3. As thermal insulation 3 is airproof, heat carrier soaks into it or under relatively high temperature saturates heat carrier with its vapour which leads to significant enhancement in electric conductivity of thermal insulation 3 in the leakage point. Pipe 2thermal insulation 3metal sheets 4 loop closes-in and electric signal is transferred from pipe 2 through minimal thermal insulation 3 electric resistance by the shortest route to the closest arch shaped metal sheet 4 and later on through cords 32 to measurement instrument 33. As all protective casing arch shaped metal sheets 4 are electrically insulated from each other and are connected by their own electric cords 32 to a measurement device 33, this measurement instrument 33 accurately detects leakage under a specific sheet.

(13) It is evident, that pipe 2 leakage detection accuracy depends on the dimensions of the separate metal sheets 4 that comprise the pipeline protective casing. The smaller is the square of the metal sheet 4, the better is the accuracy of the leakage detection. Therefore protective casing design must be thoroughly divided by sections.

(14) It must be noted that proposed protective casing design of joined separate metal sheets 4 makes an access to the leakage location on the pipe 2 consistently easier and thus eases its repair. One metal sheet 4 can be easily detached from adjacent sheets because of metal sheets 4, dielectric washers 8 and dielectric rings 10 elasticity. For this purpose it is enough to grip inside a metal sheet 4 a little bit so that its straight line bent edges 5 were released from straight line grooves 13 and 14 on the washer 8 and bent arch shaped edges 6 were released from the ring 10 ring grooves 17 and 18. In order to repair the pipe 2 there is no need to stripe out thermal insulation 3 but only detach its part which has got soaked in the radial direction. This invention is especially important for repair of large diameter pipes 2 with thermal insulation.

(15) Protective casing assembly is performed by means of arch shaped metal sheet 4 straight line edges 7 inside grip and entering of its straight line bent edges 5 into straight line grooves 13 and 14 on the washer 8 along with entering arch shaped bent edges 6 in the ring 10 ring grooves 17 and 18. While entering bent arch shaped edges 6 into the ring 10 ring grooves 17 and 18 it is needed to provide their successive reliable fixation and their electric contact with electric connector lamels 21. Metal sheets 4 joining with the washer 8 and the ring 10 is provided through metal sheets 4 bent edges 5 and 6 fixation by means of the washer 8 straight line grooves 13 and 14 walls along with the ring 10 ring grooves 17 and 18 walls.

(16) Techno-economic effect brings maintenance simplification for thermal insulated pipelines covered with a protective casing.