RU2171414C2 - Method and device for mounting oil-and-gas pipe - Google Patents

Abstract

FIELD: construction engineering; performing major repair without replacement of pipes in close-to damage conditions. SUBSTANCE: pipe to be mounted in sealed-up by front fixed blank and repair movable blank. Gas (air) under pressure is pumped into pipe and new pipe is inserted into worn pipe by action of stop of transport facility on movable rear blank. EFFECT: facilitated operation; reduced tractive force. 3 cl, 2 dwg

Description

 The invention relates to the pipeline transport of petroleum products and gas and for the restoration of service characteristics of pipelines.

 During operation, oil and gas pipes corrode. As a result, shells form on the inner and outer surfaces of the pipes, and the pipe wall becomes thinner. This leads to accidents - ruptures of oil and gas pipelines, since the working pressure in the pipes, ensuring the transport of oil and gas in them, already creates a voltage in the pipe walls that exceeds their strength. The natural fatigue of metal pipes occurs. Pipeline service life reaches the limit, the age of many main oil pipelines exceeds 30 years.

 The consequences of such accidents lead not only to the loss of oil and gas, but also when the pipes are destroyed over a long length, they poison the adjacent land and water bodies, and burn out the vegetation [1].

 The elimination of the consequences of accidents and the restoration of the destroyed section of the pipeline and the adjacent areas and reservoirs are expensive, and the losses are irreparable ([1], [2], p. 28).

 It is necessary to ensure the reliability of pipelines by overhaul with the replacement of pipes, which is associated with a large amount of excavation, determined by the method of overhaul.

 There is a method of preventing accidents in oil and gas pipelines, which consists in the fact that overhaul of a section of the pipeline is in pre-emergency condition. According to this method, the trench in which the pipeline is located is dug up, the damaged section of the pipeline is removed, a new pipe is laid in its place in the trench, connected to the pipeline, the trench is buried and the adjacent area is restored ([4], p. 107, [5] p. 257, 258). This method is very time-consuming and more expensive than the construction of a new section of the pipeline, since, in addition to the work associated with laying a new pipe, it includes a number of additional works to remove the worn-out part of the pipeline.

 At the same time, earthworks account for at least 30% of the cost of all pipeline construction works.

 Known considered as a prototype method and device, including laying a new pipe inside the worn part of the pipeline. The new pipeline is drowned from the front and rear ends, connected by a thrust to the conveying device and introduced into the old pipeline [6].

 A “pull” in the method and device under consideration may use a cable, while the transporting device — the tractor or winch — is located outside the worn-out part of the pipe.

 With a large pipeline length, traction increases, which requires a large diameter cable. This causes difficulties in working with such a cable ([5], p. 257, 258).

 In the case of a short "traction", it is possible to use a self-propelled apparatus placed inside the old pipe to move a new pipe to be laid [6]. The disadvantage here is the inability to create a large pulling force with a large length of the pipe to be laid. This is determined by the fact that the adhesion of the self-propelled apparatus with the inner wall of the worn pipe is limited. The adhesion force determines the pulling force, and therefore, the length of the pipe to be laid is limited.

 The objective of the invention is the overhaul of oil and gas pipelines by transporting and laying a new pipe inside a worn pipe with minimal excavation and increasing the length of the pipe.

 This is achieved using the method and device for its implementation.

In FIG. 1 shows a device for transporting and installing an oil and gas pipe;
in FIG. 2 shows a diagram of the acting forces on the installed pipe.

 The device (Fig. 1) contains plugs 1 and 3, placed at the ends of the installed pipe 2, the flange-guide 10, transporting means 4 (tractor, car), stop 11.

 When installing a new pipe, support 5 and pipe layer 6 are used.

 The method of installing a new pipe inside a worn pipe is as follows.

 On the route of the worn pipe 8 (Fig. 1), at the beginning and the end, two pits are excavated working (back) and receiving (front) along the pipe 2 to be laid. The sections of the worn pipe 8 located in the pits are removed.

 The pipe 2 to be installed is prepared for installation: it is sealed by closing its front end with a plug 3 fixed relative to it, the rear end of the pipe 2 is closed with a plug 1 movable relative to the pipe being installed, and the plug is abutted through the stopper 11 in the conveying means 4. The front end of the pipe 2 being laid is placed on a support 5 and support the pipe layer 6, the conveying means 4 and the stop 11 move the movable plug 1 and set it so that it does not abut against the flange-guide 10.

 Then the pipe 2 is filled under pressure with air, it is released from the pipe layer 6, the pressure in the pipe 2 is raised until it begins to move into the worn pipe 8, at the same time, the movable plug 1 is set in motion by means of the transporting means 4 and the stop 11.

 Since when bringing a stacked pipe from a state of rest to a state of motion, more effort is required than effort to maintain a constant speed of its movement, then when the required speed of the pipe is reached, the air pressure in it is reduced to a value that determines the constant speed of movement of the stacked pipe. Pipe 2 is moved until its front end exits into the receiving pit, while the rear end is placed with the help of the pipe layer 6 in the working pit on the table 5. The plugs 1 and 3 are removed and the rear and front ends of the laid pipe 2 are connected and connected through the adapters with the corresponding ends of the working pipes 7 and 9, the support 5 is removed from the pits and the pits are buried.

 Therefore, to move the stacked pipe, there is no need to create axial tensile stresses in it to maintain stability by injecting compressed air into the sealed stacked pipe.

 The driving force moving the pipe will be the pressure force of the air (gas) on the plug of the front end of the pipe. The installed pipe will be stretched by this force and the forces of resistance (friction). This makes it possible not to fear the loss of longitudinal stability of the installed pipe and to take its very large length, which makes the proposed method very economical, since the length of the excavated pits is small compared to the length of the old pipe, which is not excavated.

 Thus, excavation on the section of the oil and gas pipeline route in which the new pipe is located is excluded.

 The length of the stacked pipe is determined by the conditions of interaction of internal and external forces applied to the installed pipe.

 In FIG. 2 shows the forces acting on the installed pipe 2, on the plugs 1 and 3, the stop 11 and on the conveying means 4.

The air pressure p inside the pipe to be laid creates forces Q = p • S _n acting on the front plug 3 and the rear movable plug 1. Here, S _n are the areas of the inner surfaces of the front and rear plugs.

Сила Q, действующая на подвижную заглушку 1, воспринимается упором 11 и транспортирующим средством 4, которое удерживает заглушку 1 от перемещения в сторону действующей на нее силы Q. На перемещаемую трубу будет действовать и внешняя сила сопротивления трения между наружной ее поверхностью и внутренней поверхностью старой трубы. Величина этой силы, действующей на единицу длины трубы q = G₁ • f_пр, где G₁ - вес единицы длины трубы, a f_пр - приведенный коэффициент трения между наружной поверхностью перемещаемой трубы и внутренней поверхностью старой трубы.where D is the outer diameter of the installed pipe; δ - pipe wall thickness

The force Q acting on the movable plug 1 is perceived by the abutment 11 and transporting means 4, which keeps the plug 1 from moving towards the force Q acting on it. The external frictional resistance force between its outer surface and the inner surface of the old pipe will also act on the movable pipe. . The magnitude of this force acting on the unit length of the pipe q = G ₁ • f _CR , where G ₁ is the weight of the unit length of the pipe, af _CR is the reduced coefficient of friction between the outer surface of the moving pipe and the inner surface of the old pipe.

Literature
1. A. Shinkin. Everything can fly into this pipe. Russian newspaper, 02/27/1997

 2. Yu. Rubin. Royal chip. Securities Market Magazine N 20 (107). 1997, p. 28.

 3. Pipeline transportation of oil. Special issue TransPress Publishing House. 1997, pp. 29, 36, 67, 73, 107.

 4. G. F. Egerman and others. Repair of gas pipelines. M .: Nedra, 1973, p. 107.

 5. P.P. Borodavkin and others. The construction of gas and oil pipelines. M .: Nedra, 1987, p. 257, 258.

 6. EP 0149528 A1, 07.24.1985, E 21 B 7/26; pg. 1-5.

Claims (2)

 1. A method of installing an oil and gas pipe in a worn pipe, which consists in sealing a new oil and gas pipe with front and rear plugs, connecting the rear plug with a conveyor and introducing a new oil and gas pipe into a worn pipe, characterized in that the rear plug is movable, the thrust is in the form emphasis, and the introduction of a new oil and gas pipe into the worn pipe is provided by pumping air (gas) into it under pressure and moving the movable rear plug in it guide means through the abutment.  2. A device for installing an oil and gas pipe into a worn pipe, including a conveyor, a guide flange at the rear end of the installed pipe, a plug at its front end, fixed relative to the installed pipe, and a plug at its rear end, characterized in that the rear plug is movable relative to installed pipe, and rests the back cap by focusing on the conveyor.

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