FI105017B - Procedure and plant for lining installed pipelines - Google Patents

Description

105017

The present invention relates to a method for lining installed pipelines, which method comprises the step of: using a tensile tension drive device attached to the front end of the liner and threaded through the pipeline, pulling the liner through a tension press to reduce the outer diameter of the liner, and preheating the liner prior to exiting the liner, the position being reduced in dimension and / or maintained in a dimension smaller than the inside diameter of the pipeline and subsequently allowing linings expansion of the tube within the pipeline by relieving said tensile stress. The invention will be described in the gas, oil and water supply pipes. but it is obvious that the invention can be applied · · • · «! '! for all types of pipes.

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When installed pipes (which are embedded in the ground are prone to cracking under the influence of earth movements), it is known to pass the heated plastic pipe liner • · 'through a nozzle or clamp to reduce the diameter and then to an existing pipe for a certain length.

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Vr. The present invention relates to an improved method of lining an installed pipe / tube when using a tension clamp to reduce the diameter of the liner before it is drawn into an existing pipeline. "Installed" pipeline means a pipeline that has already been installed. : intended purpose, such as submerged pipelines for gas, oil, water or waste water, pipelines forming part of a larger facility such as an oil or gas refinery or storage facility, or pipelines lying on the ground and are installed to connect the access point to the recipient, such as an oil pipe connecting the oil source to the refinery or port.

For an embedded pipeline, it is evident that the normal system for carrying out such a process will include a winch placed adjacent to the trench at one end of a certain length of lined pipe, from which the cable or similar flexible connection passes through the pipe to the other trench secured to the front end of a plastic lining tube. Next to the second trench is a heating and compression device comprising a heater and a size reduction device. The downstream end of this device may have a reciprocating "pusher" that can grab onto and pull the tube and force it toward the lining tube.

According to the invention, the outer diameter of the lining tube is reduced = · '; up to 15%, whereby tension relaxation is followed by memory-induced expansion at normal atmospheric pressure and pipeline ambient temperature, whereby the tensile stress exerted by the traction device is such that it partially limits the radial ··· expansion of the liner surface after exiting the press. The tension clamp »· · is attached to the pipeline at a distance therefrom and the lining tube is cooled in the space between the tension clamp and the pipeline in the · · · V * exit of the liner pipe.

In one embodiment of the invention, the liner can be heated by methods known per se prior to the drawing operation. Alternatively, the liner may be <fii! in addition, it heats as it passes through the tension press. In such a case, there is provided a device for heating the inner surface of the tension press 3 105017 while passing the liner tube therethrough.

According to another embodiment of the invention, the tensile compression operation may be performed at ambient temperature. For example, the choice of liner tubes for tension extraction at ambient temperature will depend, for example, on the dimensioning of the liner, its SDR ratio and the characteristics of the material of which the liner is made. If the liner can be successfully pulled at ambient temperature under certain conditions, it is an easy task for the user to find out by trial and error.

The present invention contemplates, in a suitable embodiment, the use of a tension press provided with a surface inclined at or between 6 ° to 32 °, wherein no part forms an angle greater than 32 ° with the tension of the tension press and extends at least 70% of the axial distance between the part where the liner tube meets this surface and the part where the liner tube exits the tension press.

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According to prior art tube extraction methods: the tensile presses used are practically composed of two sections, the first being a sloping compression surface which i · ”1 reduces the diameter to a minimum value and the other is an axial II · tensile press interior extension with tensile compression walls. axial and the inside diameter corresponds to this minimum value. We have found that in carrying out the invention it is advantageous to · · · V 'shorten the axial length of said second part - ···: relative to the axial length of the first part, or t ·'? otherwise, omit the other part completely. By designing the tensile press I, the first part 4 has an axial distance of at least 70%, preferably: fl1: more than 80%, and preferably more than 85% of the axial distance between the part where the liner meets the inclined surface and the outlet 105017 4, where the tube exiting the tension press, the tensile stress required for pulling the liner tube through the tension press, in particular, is substantially reduced. Another consequence of using such a tension press to carry out the invention is that when using a liner tube which is a synthetic hydrocarbon resin such as polyethylene or modified polyethylene which is commonly used in practice, the liner tube exits such an outlet , as in the prior art, the tension press was provided with a second portion having a substantial length, as described above, typically in the order of 50% of the total length of the tension press. When the tensile stress is relieved, such tendency will result in a greater relative radial expansion compared to the tensile stress used than with prior art tension presses.

This process of the invention is based both on the expansion of the liner tube due to the relaxation of tensile stress in the pipeline; as well as memory expansion of the tension lined tube. By using a tension clamp, the axial length of the second portion being reduced relative to the axial length of the first portion, as described above, the relative expansion due to stress relaxation can be greatly increased, thereby improving the controllability of the tubing lining operation.

In addition, the above arrangements bring with it a considerable advantage over the situation in which a "push" type device, such as that provided in our parallel patent application GB 8806926, is used. of the type shown. The use of this type of pusher is due to the fact that when it engages the a · · torsion tube and forces it towards the liner to be lined: there is a temporary reduction in the tensile stress exerted by the puller (such as the winch) at one end of the tube. As the grip on the pusher loosens, the tension returns to its former value. This results in virtually constant tensile stress variation. It is desirable that alternation between maximum and minimum stresses during oscillations is made as uniform as possible with a minimum of rapid changes or jerks.

We have found that when tensile presses of the invention are used which require substantially lower tensile stresses to achieve a comparable degree of compression with prior art tension presses, and which are also due to the greater "bounce" and "tensile" tendency of the tube exit the fluctuations themselves become more even. Given the very high forces involved in applying tensile stress, this is again a significant improvement in both operational safety and efficiency.

One step of the process of the invention; the length of the pipeline to be lined can typically be 10 * I (upwards from the meter. The length of the pipeline that may be lined in a given:, · situation will depend on the combination of factors 'Li.' which include frictional resistance against the lining movement. , the extent to which reduced shark-

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· ”The lining tube with a ratchet, the insertion ice c · · '·' becomes susceptible to deformation (a problem with larger diameter liners having a relatively high SDR ratio), tensile stress at the front end of the liner beyond which it may exhibit permanent - damage or permanent elongation, the capacity of the drive mechanism (such as a winch) and the uniformity of the diameter and / or orientation of the pipeline interior. In practice, the most appropriate practice in a given case can be easily determined by trial and error.

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The method according to the invention makes it possible to line pipelines which can be up to 450 meters in length or more. The surface finishing of the tension press can be accomplished by means known in the art. The surface quality should at least correspond to grade N7, typically N6, even N5, and ideally to about N4 or better.

It has been found to be advantageous to use a tension press in which the inclination surface of the tension press is relatively sloping with respect to the tension of the tension press, being in the range of 12 ° to 29 ° and most preferably 20 ° to 25 °. Reducing the angle helps reduce the tensile load required to achieve compression of the liner tube, while at the same time increasing the tensile press surface by any degree of compression. The optimum angle will be that which, in any given situation, minimizes the overall drawbacks caused by the high load, on the one hand, to provide compression, and, on the other, to provide a high friction-producing tension surface. The tensile press surface may be in the form of a truncated cone. Alternatively, its angle of inclination with respect to the tension of the tensioning clamp may be varied within the above frames. An important and advantageous feature of the present invention is that when using its deformable memory f <<; * 1 './. A liner made of a preservative material in accordance with the * * method of the invention, the liner may be left in the radially lined piping of the expansion under the influence of the memory of the material from which it is made. During the appropriate lining tube initial diameter, the degree of compression tension during the compression operation and the choice of the tension presser outlet • · · sis, the inner diameter of the pipe to be lined, · *? with respect to the rig, the invention can provide a tight lining suitable for a local pipeline, which (after the tension is applied) is a consequence of the memory lining of the pipe lining.

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secondary expansion at ambient temperature and pressure ϊ * '. I inside the pipeline. In this context, it is not necessary to rely on prior art methods for expanding pipe liner within the pipeline, such as applying internal overpressure or heat to the liner internally, or applying very high stretching forces to the liner during the initial phase, to provide initial shrinkage of the liner. The exact operating conditions used to carry out the process of the invention will, in any given situation, depend on a number of factors described above and will vary with the inner diameter and purpose of the pipeline (e.g., water or gas), pipe liner and SDR. (SDR refers to the ratio of the existing diameter of the liner before tension extrusion to the wall thickness of the liner).

According to another embodiment of the present invention, there is provided an apparatus for lining an existing pipe comprising a support structure, a tension clamp placed within the structure for reducing the diameter of the lining tube passed therethrough, a securing device for securing the structure to the lining tubing and optionally a tension extruder to heat the pipe.

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The recommended material for the liner is polyethylene, * · '1 ·; but other substances having the necessary memory-retaining properties, such as polyethylene copolymer and * · · ·. '' at least one alpha-olefin having up to ten carbon atoms, may also be used. Although the reduction in the diameter of the liner pipe ··· '· / · may be up to:'? 'R 15% during passage of the tension press, a reduction of 5.0 ... 9.8% is most appropriate. Decrease /; should be such that the liner can be pulled through an existing tube. This somewhat simple requirement was complicated by the fact that the internal dimensions of existing pipes are often not very accurate, that the inner diameter of the pipe may vary in length, that the degree of recovery of the liner pipe may vary according to environmental conditions and material. from which the tube is made. The wall thickness of the lining pipe should be as small as possible and consistent with the intended use of the pipe and provide a reliable internal seal of the existing pipe. A ratio of wall thickness to liner diameter of 10 to 46 is preferred.

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The selected maximum tensile stress for drawing the liner pipe through the existing pipe should preferably be between 45 and 55%, in particular about 50% of the yield limit of the liner in question. The ratio between the die diameter of the drawing press and the diameter of the existing pipe should preferably be between 1.05: 1 and 1.15: 1. A reciprocating pusher may be used to increase tensile stress exerted by said puller to pull the liner tube through the tension press.

In order that the invention may be more clearly understood, an embodiment of the invention will now be described by way of example with reference to the accompanying drawing, in which: Figure 1 is a sectional side view of an embodiment of the device of the invention;

Figure 2 is a sectional side view of a modified embodiment of the device shown in Figure 1.

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Referring to Figure 1, the device comprises a support structure 1 including a tube clamp 2 at one end and a tension clamp 3 at one end * · '* The tension clamp 3 is generally cylindrical and comprises a larger diameter portion 4 connected to a smaller diameter part 5 by means of a conical part 6. The tensile press is provided with: a polished pressing surface which forms an angle of 6 to 32 ° 9105017 with the tension of the tension press, the inclination being preferably 12 to 29 ° and preferably 20 to 25 °. The surface quality of the polishing is at least of the order N7, typically up to N6, preferably up to N5 and ideally of the order of N4 or better. The ratio of diameters of 4 and 5 is preferably between 1.05: 1 and 1.15: 1. This has been found to provide sufficient clearance between the pipe liner and the inner diameter of the pipe for most normal pipes and is well suited to the framework for material diameter recovery.

The body of the tension press 3 in the illustrated embodiment is hollow and includes an electric heating coil 8 which is supplied with electricity through an electric supply circuit 9. A force is applied to the heating coil to heat the liner to a temperature of 350 ° C to 95 ° C and preferably about 50 ° C. When exiting the tension press, the lining tube is cooled by means of an annular heat exchanger 12 located around the tube and which removes heat from the tube. The heat exchange medium may be carbon dioxide, air, water or any other suitable liquid.

The pipe clamp 2 is secured to the free end of the existing pipe and, together with the existing pipe designated 10, forms a stop against which the lining pipe 7 can be pulled. The support structure to which the pipe clamp is connected may be tubular or may consist of a plurality of arms connecting the pipe clamp 2 and the tension clamp 3.

··· • ··. · * When using the device, a certain length of liner tube of polyethylene or other suitable material 7 may be bevelled or ::: efficiently preformed at one end to form a tip cone: * · '· to the end on which the notched metal tip cone can be fitted . The preferred ratio between wall thickness and liner diameter is 10 ... 46. The chamfered parts are formed with holes aligned with the holes in the metal tip cone and through which the cable is connected to the pipe. The cable is threaded through a tension clamp 3 and an existing pipeline and connected to some type of suitably secured pulling device, such as a winch. The power supply is turned on to heat the tension press to the desired temperature and the bevelled end of the lining tube is introduced into the upstream end of the tension press. The cable tension is increased to the required value (usually 45 ... 55%, especially 50% of the yield limit of the liner in question) until the liner begins to move through the tension clamp and retracts into the existing pipeline. In this way, the liner pipe is pulled completely through the existing pipe. The cable is disconnected, and then the memory property of the pipe material may expand the pipe until it comes into contact with the inner surface of the existing pipe.

The passage of the pipe through an existing pipe can be facilitated, if desired, by a liner pusher. Such an arrangement is shown in Figure 2 of the drawing. Referring to this figure, a pusher, which generally comprises a body 21, a hydraulic cylinder 22, a clamping ring 23 and auxiliary devices, is disposed between the tension clamp 3 and the pipe clamp 2. In use, this machine pulls the liner tube through the tension clamp 3 and pushes it into the existing pipeline.

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It will be apparent that the above embodiments have been explained ··· * by way of example only and that many variations are possible without departing from the scope of the invention. For example, the liner tube · · · · may be heated before being introduced into the tension press and stretched as described in the co-pending application GB-2186340; * · *:

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Claims (4)

A method of lining installed pipelines, which method comprises the stage of taking a lining tube of a certain length, which tube is of a plastic material which retains its memory and whose outer diameter is greater than the inner diameter of the piping provided with the lining, and using a tensioning device which strengthens under tension and which is fixed at the front end of the feed tube and threaded through the conduit, that the feed tube is pulled through a pull press to reduce the outer diameter of the feed tube, and that the feed tube is preheated before removing from the draw press, that pulling the casing through the assembled pipe while reducing the outer diameter of the casing to and / or maintaining at a dimension less than the inside diameter of the casing and subsequently allowing the casing to expand within the pipeline by extinguishing said tensile stress, that you shrink lining the outer diameter of the pipe up to 15%, that the yield of said tensile stress is followed by a memory-related expansion at normal air pressure and the temperature of the pipeline (10) environment, the tensile stress exerted by the tensile devices being such that it partially restricts the radial expansion of the feed tube. outer surface where it is removed from the drawing press, that the drawing press (3) is fixed in the pipe (10) at a distance: Y; from the same and that the cooling tube (7) is cooled in the space <! j between the draw press (3) and the pipe (10) where the feed pipe (7) • · t ·. ···. removes from the drawing press (3). «* · T Method according to claim 1, characterized in that the casing (7) is preheated to a temperature which is between 30 ° C and 90 ° C. • · · «« «* * · · · V The method according to claim 2, characterized in that the feed tube (7) is preheated to a temperature ranging from 30 ° C to 65 ° C. Method according to claim 3, characterized in that the feed tube (7) is preheated to a temperature ranging from 45 ° C to 55 ° C.