RU2075003C1 - Method of retesting operating pipe line - Google Patents

Abstract

FIELD: operation of pipe lines. SUBSTANCE: product of pipe line is replaced with water fed under pressure from filling unit; divider delivered from starting chamber is placed at boundary of water and product; then pipe line is subjected to pressure test. Volume of water pumped into pipe line exceeds volume of potentially dangerous section between two linear gates bounding this section by 5 to 10 percent. Then second divider is delivered from starting chamber forming water lock which is moved to dangerous section before applying test pressure. EFFECT: enhanced reliability. 4 cl, 2 dwg

Description

 The invention relates to tests and may find application in the operation of pipelines.

 Known methods for re-testing existing pipelines.

 One of them, in the event that a section of a pipeline that is potentially dangerous for rupture is detected, consists in disconnecting this section from neighboring sections by cutting the pipe and installing plugs, filling the plugged section with water and crimping it (see A. Gumerov et al. Hydraulic tests of existing oil pipelines, M. Nedra, 1990, p. 210). However, characterized by a sufficiently high environmental friendliness due to the use of a small volume of injected water, the method is time-consuming, since it involves cutting the pipeline.

 The closest technical solution to this invention, adopted as a prototype, is a method of re-testing the existing pipeline, which consists in replacing the product in the pipeline with water supplied under pressure from the filling unit, with the separation of water and the product of the separator launched from the start-up chamber, and crimping the pipeline (see ibid., p. 30).

 The disadvantage of this technical solution, which does not require cutting the pipeline, is the need to draw and purify a large volume of water, since the entire pipeline is filled with water at the final stage of its supply.

 The objective of the invention is to reduce water consumption during re-testing in the event of preliminary identification of a potentially dangerous pipeline rupture.

 To achieve the required technical result in the method of re-testing the existing pipeline, which consists in replacing the product in the pipeline with water supplied under pressure from the filling unit, with a separator launched from the start-up chamber at the interface between the product and the water, and crimping the pipeline, water is pumped into the pipeline in volume exceeding the volume of a potentially hazardous section of a pipeline section between two linear valves restricting this section by 5-10% is placed starting from start-up measures at the end of the water volume, the second separator forms a water plug and, before pressure testing, moves the latter to a potentially hazardous section of the pipeline section with its overlapping pipeline volume between the said linear valves. In addition, water plugs are placed in the pipeline in all areas with potentially dangerous sections.

In addition, when re-testing the gas pipeline in it previously, before the formation of the water plug, create a pressure P _p gas, determined by the formula:
P _p P _isp (L ₁ -L ₂ ) / L _t , (1)
where P _isp pressure pereispytaniya;
L _{1 the} distance between the safety tap and the linear valve restricting a potentially hazardous area;
L _{2 the} distance between the separator and limiting the potentially hazardous area of the linear valve at a pressure in the gas pipeline equal to P _isp .

L _{t is the} length of the re-tested gas pipeline.

The distance L ₂ is determined by the formula:
L ₂ L ₁ (1-P _slave / P _isp ) + L _s , (2)
where P is the _slave working pressure in the gas pipeline;
L _{s the} distance equal to the movement of the separator when the gas pipeline ruptures during its overlap by a linear valve.

In addition, the excess of the length of the water plug over the length of the potentially dangerous section of the gas pipeline limited by linear valves is determined by the formula:
L _in L _uch L ₂ + L _s , (3)
where L _{is the} length of the water plug;
L _{uch the} length of the potentially dangerous section of the pipeline bounded by linear valves.

 Distinctive features of the invention are not present in these and other sources known to us, the proposal, in our opinion, is not known from the prior art and therefore new.

 In FIG. 1 schematically shows an existing pipeline with piping and equipment for re-testing; in FIG. 2 he, at the stage of exposure under the pressure of re-testing.

The method of re-testing the existing pipeline is to replace the product in the pipeline 1 with water supplied under pressure from the filling unit 2, with a separator 3, launched from the start-up chamber 4, placed on the border of the water and the product, and crimping the pipeline. Water is pumped into the pipeline in a linear volume L _in excess of the volume of a section of the pipeline section 5 potentially hazardous to rupture between the two linear valves 6 and 7 that limit this section and 5-10% placed the second separator launched from the launch chamber 4 at the end boundary of the water volume 8 with the formation of a water plug and before crimping, move the latter to a potentially hazardous section of the pipeline section 5 with the overlap of the pipeline volume between the said valves 6 and 7.

 Water plugs are placed in the pipeline in all areas with potentially dangerous stretches.

 Operationally, the work is performed as follows.

 Before re-testing through pipeline 1, a cleaning piston is passed to remove contaminants and condensate and a diagnostic tool to determine the actual condition of the pipeline. Based on the results of inspection with an in-line flaw detector or other method, a section 5 (or sections) of the pipeline is determined, in which the probability of destruction will be significantly higher compared to other sections. The length of the section (s) is taken equal to the distance between the closure valves 6 and 7 closest to the zone of probable rupture.

 Two separator pistons 3 and 8 are stored in the stationary start-up chamber. Then the product is shut off to the pipeline by shutting off the valve 9. The valve 10 is opened and water is supplied by the filling unit 2 from the water source 11 through the valve 12 to the start-up chamber 4 between the pistons 3 and 8, wherein the piston 3 exits the start chamber and moves through the pipeline. When the length of the water volume between the pistons 3 and 8 exceeds the length of the allocated portion 5, the water supply is stopped, the valve 12 is closed and, opening the valve 13, the piston 8 is pushed out by the product stream into the pipeline. By closing the valve 10 and 13 and opening the valve 9, the formed water plug in the product flow is moved to the selected area 5. When the piston 3 passes the linear valve 7, the pumping is stopped, while the piston 8 stops at a certain distance from the linear valve 6. In case several sections are allocated, respectively, several water plugs are installed.

 The pressure in the pipeline is raised to the test pumping units of the pumping station, while all linear valves are open. In the event of a pipeline rupture in the selected section 5, the linear valves 6 and 7 are closed and thereby prevent product leakage into the environment.

 After re-testing, the water located between the pistons 3 and 8 is discharged into the settling tank 14 through the piston receiving chamber 15.

When re-testing the gas pipeline, similar operations are performed, with the difference that until the valve 9 is closed and the gas supply to the gas pipeline is stopped before the water plug is formed, pressure is created in it with the value of R _p determined by the formula (1). After the formation of a water plug, it moves through the gas pipeline in the direction of a potentially dangerous section during the pressure rise from the value of P _p and blocks the entire potentially dangerous section of the gas pipeline, limited by linear valves 6 and 7, when the pressure in the gas pipeline is equal to P _slave .

 Thus, due to the use of water in a volume exceeding the volume of the pipeline section between two adjacent linear valves, only 5-10% reduction in water consumption is provided during re-testing.

Claims (4)

 1. The method of re-testing the existing pipeline, which consists in replacing the product in the pipeline with water supplied under pressure from the filling unit, placing a separator launched from the start-up chamber at the interface between the water and the product and crimping the pipeline, characterized in that the water is pumped into the latter in volume , exceeding the volume of a section of a pipeline section that is potentially hazardous to rupture between two linear gate valves that limit this section, place the valve launched from the start chamber on the end Nice aqueous volume of the second separator to form a water plug and before crimping is moved to the last segment having a potentially dangerous conduit portion overlapping its volume conduit between said linear valves.  2. The method according to p. 1, characterized in that the water plugs are placed in the pipeline in all areas with potentially dangerous segments. 3. The method according to p. 1, characterized in that when re-testing the gas pipeline in it, prior to the formation of the water plug, a gas pressure P _p is created, determined by the formula
P _p P _isp (L ₁ L ₂ ) / L _t ,
where P _isp pressure pereispytaniya;
L _{1 the} distance between the safety tap and the linear valve restricting a potentially hazardous area;
L _{2 the} distance between the separator and limiting the potentially hazardous area of the linear valve at a pressure in the gas pipe P _isp ;
L _{t the} length of the re-tested gas pipeline,
the distance L ₂ is determined by the formula
L ₂ L ₁ (1 P _slave / P _isp ) + L ₃ ,
where P is the _slave working pressure in the gas pipeline;
L _{3 the} distance equal to the movement of the separator when the gas pipeline ruptures during its overlap by a linear valve. 4. The method according to PP. 1 and 3, characterized in that the excess length of the water plug over the length limited by linear valves of a potentially dangerous section of the gas pipeline is determined by the formula
L _in L _uch L ₂ + L ₃ ,
where L _{is the} length of the water plug;
L _{uch the} length of the potentially dangerous section of the pipeline bounded by linear valves.

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