WO2013184022A1

WO2013184022A1 - Method and unit for applying insulation on the outer surface of pipelines

Info

Publication number: WO2013184022A1
Application number: PCT/RU2012/000494
Authority: WO
Inventors: Ivan Ivanovich RASSTRIGIN
Original assignee: Rasstrigin Ivan Ivanovich
Priority date: 2012-06-05
Filing date: 2012-06-22
Publication date: 2013-12-12
Also published as: RU2012122893A; RU2509950C2

Abstract

This invention relates to the construction and repair of underground utility lines and can be used for the insulation of metallic surfaces from the combined effect of moisture and oxygen, preferably, for the insulation of steel pipeline surfaces.

Description

Method and Unit for Applying Insulation on the Outer Surface of

Pipelines

This invention relates to the corrosion protection of metallic surfaces, preferably, pipeline transport, and, more specifically, to the construction and repair of underground utility lines, and can be used for the insulation of metallic surfaces from the combined effect of moisture and oxygen, preferably, for the insulation of steel pipeline surfaces.

Known is (Construction of Main and Field Pipelines. Corrosion and Heat Insulation, VSN 008-88. Moscow, Minneftegazstroi, 1990, p. 10) a method of applying insulation tape on the outer surface of pipelines. In accordance with the known method, the surface to be insulated is preliminarily cleaned, and then the primer and the polymer insulation tape are applied onto the pipeline, and if the ambient air temperature is below 10°C the pipeline surface is heated to at least 15°C but not higher than 50°C.

Disadvantage of the known method is the necessity of frequent and relatively long interruptions of the application process for replacing the insulation tape coil and joining the insulation tape of the spent coil with the insulation tape of the new coil.

Known is a method of applying insulation mastic on pipelines (RU Patent 2174642, 2001) comprising heating of bitumen base insulation mastic in the extrusion chamber, in the mastic containers and in the supply hoses and pumps and extrusion of the insulation mastic through the shaping discharge port of the extrusion chamber followed by wrapping the newly applied mastic layer with protective tape unwound from coils. The known method provides coating application that fills surface roughness but requires frequent and relatively long interruptions of the application process for replacing the insulation tape coil and joining the insulation tape of the spent coil with the insulation tape of the new coil.

Application of insulation tape coatings on long pipeline sections can be achieved using devices comprising a dismountable rotor moving along the pipeline on a threaded guide and unwinding the insulation tape from the coil mounted on the winding head of the rotor onto the pipeline surface (see e.g. RU Patent 2218515, 2003).

Known are (RU Patent 2303743) a method and a device for applying insulation coatings on pipelines comprising helically winding the insulation tape from a replaceable coil onto the preliminarily cleaned pipeline surface coated with a primer layer wherein the insulation tape is two-layered thermoplastic tape with a polymer adhesive material, during winding the preliminarily unwound tape is shaped to a coil with a diameter greater than that of the pipeline, the tape is turned its adhesive side away from the pipeline, the unwound section of tape is heated to the plastic transition point of the adhesive material, the tape is turned its adhesive side to the pipeline, and when the adhesive layer touches the pipeline surface the tape base is pressed down with a distributed load to spread the adhesive material for filling any roughness on the pipeline surface and displacing the air from under the tape with the simultaneous retaining of the tape edge at the point of overlap with the previous tape wind and the application of tensile stress growing from the overlapping tape edge towards the opposite tape edge.

It is suggested to implement the known method using a device for the application of insulation coating on pipelines comprising a dismountable rotor capable of resting with its rubber-coated rolls on the pipeline surface and having at least one winding head on which replacement insulation tape coils can be installed and a driven carriage with an electric drive comprising an electric motor, a reducing gear and toothed gears, said carriage having support rolls for resting on the pipeline wherein said driven carriage is linked with said rotor via tie rods. The known device further comprises a primer container having a piston, a batcher and a tool for primer spreading over the pipeline surface, an insulation coating heater capable of translational motion along the pipeline and resting at one side on said rotor with a pair of wheels and at the other side capable of resting on the pipeline on which the insulation coating has already been applied, said rotor can be connected to a power source via sliding contacts and accommodates rolls that guide and unwind the insulation tape, a heat insulating sheath that guides the insulation tape, allows shaping the tape into a coil with a diameter greater than that of the pipeline and is connected via an air duct to a continuous flow air heater that heats the insulation tape at the adhesive side, and a tool for spreading the heated adhesive material of the insulation tape over the pipeline surface capable of retaining the tape edge at the point of overlap with the previous tape wind and applying tensile stress growing from the overlapping tape edge towards the opposite tape edge. Disadvantage of the known technical solution is the necessity of frequent and relatively long interruptions of the application process for replacing the insulation tape coil and joining the insulation tape of the spent coil with the insulation tape of the new coil.

The closest counterpart of the technical solution provided herein is (RU Patent 2375633) a method of applying insulation on the outer surface of pipelines comprising unwinding the insulation tape from the coil and winding it onto the pipeline wherein the coil is retained in the direction of its rotation about the pipeline and part of the insulation tape is wound onto a storage device surrounding the pipeline.

The closest counterpart of the device provided herein is (RU Patent 2389942) a machine for applying insulation coating on the surface of pipelines comprising an apparatus for applying the fluid component of the insulation coating and an apparatus for applying the insulation tape, the latter apparatus comprising at least one storage device for tape (coiled) materials made in the form of circularly arranged axially oriented (along the pipe) freely rotating rolls and a tape guiding and tensioning device.

Disadvantage of the known device and machine for its implementation is the necessity of interrupting the application process for a long time for joining new tape with the end of the spent tape. Said disadvantage is due to the fact that the maximum length of the tape that can be stored in the storage device which is in fact an additional wind of the tape on the axially oriented rolls is nD_pipe + 10- 15% regardless of the diameter of the pipe to be insulated. That is, given the actual linear speed of the insulating machine of 1 m per minute, the standard tape width of 225 mm and the useful linear stroke of the insulating machine of 200 mm per 1 turn (the wind overlap width is 25 mm), the angular speed of the machine will be about 5 turns per minute. This means that the storage device resource (the time in which all the tape will be unwound from the storage device) is not greater than 1/5 min or about 12-15 seconds. This is the cycle during which the operator should perform the following sequential operations: stop unwinding the ending tape coil, insert the end of the coil into the gluing device, prepare the beginning section of the next tape coil for gluing, insert the beginning section of the next tape coil into the gluing device, apply the glue and spread it over some area, connect the ends of the tape coils, press the tape coils to each other, perform the gluing cycle itself, reinstall the tape coils and start the unwinding drive motor. It is physically impossible to perform all these operations in such a short time. Even if the insulation tape width is 450 mm, then at a 1 m per minute speed the working time of the storage device will be about 30 seconds which is still hardly sufficient for performing all the above operations.

The object of this technical solution is to reduce the application process interruption time required for replacing the insulation material coil and eventually completely avoid application process interruption.

It is suggested to achieve said technical result using the method of insulation application on the outer surface of pipelines provided herein. In accordance with the method provided herein, the insulation tape is unwound from a coil installed on a spool carrier, drawn through the storage device, helically wound onto the pipeline and retained on the pipeline, followed by jointing a new tape coil once the current tape coil is spent, wherein the tape storage device is arranged between said spool carrier and the pipeline, the insulation tape is tape with adhesive material, during winding the tape that has passed the storage device is turned its adhesive side away from the pipeline, the unwound section of tape is heated at its adhesive side, the tape is turned its adhesive side to the pipeline, when the adhesive layer touches the pipeline surface the tape base is pressed down with a distributed load, the tape turned its adhesive side away from the pipeline is drawn along the rolls circularly arranged around the pipeline to be insulated at their exterior side relative to the pipeline, and the replacement tape coil is arranged parallel to the pipeline axis.

In the most preferable embodiment said storage device and said spool carriers are mounted on a bracket attached to the case of the device at a side of the pipeline. This facilitates matching the speeds of the tape application device and the coils with the storage device. However, also possible is an embodiment wherein said storage device and said spool carriers are mounted on the platform of a self-propelled vehicle moving along the pipeline.

Preferably, said storage device is a system of shafts arranged parallel to said spool carriers and capable of moving relative to one another to provide such stock of tape that is sufficient for application onto the pipeline surface during tape coil replacement. Said action is provided by the shafts comprised in said storage device. At an early stage of unwinding a tape coil said shafts move apart from one another to provide a stock of tape, and at the final stage of unwinding the tape coil said shafts move towards one another to transfer the stock of tape to the pipeline, with the end of the tape from the spent coil being retained in place to facilitate joining the tapes of the spent and the new coils. The storage device can be driven either independently or by the drive motor of the tape application device. However, other types of storage devices can also be used.

In a preferred embodiment of this method, thermosetting base tape is used as the insulation tape. This can be, for example, tape the base layer of which is made from radiation modified polyolefin (polyethylene or polypropylene) base polymer and the base adhesive layer of which is made from an ethylene and vinyl acetate copolymer.

Preferably, the helically wound tape is evenly heated for increasing the adhesion strength between the applied tape and the pipeline surface.

A primer layer can be preliminarily applied to the pipeline surface.

During tape coil replacement, the end of the insulation tape of the spent coil is joined with the beginning of the insulation tape of the next coil using any known method (overlap glued, mechanically joined with rivets etc.).

Preferably, insulation tape is wound onto the preliminarily cleaned pipeline surface. The necessity of this operation depends on the type of the adhesive material used. Furthermore, in some embodiments of this method tape application onto the pipeline surface is preceded by heating the tape section being applied to the plastic transition point of the adhesive material. For obtaining the best protective action of the coating the adhesive material is preferably spread for filling any roughness on the pipeline surface and displacing the air from under the tape with the simultaneous retaining of the tape edge at the point of overlap with the previous tape wind and the application of tensile stress growing from the overlapping tape edge towards the opposite tape edge.

It is suggested to implement the method characterized above using the unit for applying insulation coating on pipelines provided herein. In accordance with the technical solution provided herein, the unit comprises a case, at least two spool carriers for installing insulation tape coils, a tool for pressing the tape to the pipeline surface, a heater and a storage device. Said unit allows using insulation tape one side of which has an adhesive layer, and said storage device is mounted between the case of said unit and said spool carriers, wherein said unit further comprises a system of tape guiding and unwinding rolls installed inside its case and a tool for spreading the heated adhesive material over the pipeline surface, and said system of rolls comprises at least six rolls oriented parallel to the pipeline axis and arranged circularly around the pipeline, further wherein the spool carrier of the currently unwound coil is oriented parallel to the axis of the pipeline being insulated during tape application.

As noted above with reference to the preferred embodiment of the invention, said storage device and said spool carriers are mounted on a bracket attached to the case of the device at a side of the pipeline. This facilitates matching the speeds of the tape application device and the coils with the storage device. However, also possible is an embodiment wherein said storage device and said spool carriers are mounted on the platform of a self-propelled vehicle moving along the pipeline.

Said storage device is preferably a system of shafts arranged parallel to said spool carriers and capable of moving relative to one another to provide such stock of tape that is sufficient for application onto the pipeline surface during tape coil replacement. Said action is provided by the shafts comprised in said storage device. At an early stage of unwinding a tape coil said shafts move apart from one another to provide a stock of tape, and at the final stage of unwinding the tape coil said shafts move towards one another to transfer the stock of tape to the pipeline, with the end of the tape from the spent coil being retained in place to facilitate joining the tapes of the spent and the new coils. The storage device can be driven either independently or by the drive motor of the tape application device. However, other types of storage devices can also be used.

In some embodiments said tool for spreading the heated adhesive material comprises a shaft having a retaining roll for retaining the edge of the insulation tape wherein the working surface of said shaft is formed by elastic conical washers interchanging with chafing plates.

The tape drawing rolls can be either fixed, or capable of rotating about their longitudinal axis due to the movement of the drawn tape, or capable of forced movement.

The technical solution provided herein can be implemented using the following method. Thermoplastic two-layered insulation tape oriented its polymer adhesive layer away from the pipeline surface is helically wound on the preliminarily cleaned pipeline surface. During winding of the insulation tape from the replacement coil installed on the spool carrier oriented parallel to the pipeline axis, the insulation tape oriented its polymer adhesive layer away from the pipeline surface is drawn through the storage device comprising a set of shafts oriented parallel to one another. At an early stage of unwinding a tape coil said shafts move apart from one another to provide a stock of tape unwound from the coil. After said storage device the tape is drawn inside the case over the top surface of the rolls installed circularly around the pipeline surface being insulated. When the last roll reaches the surface the two- layered tape is turned its adhesive layer towards the pipeline surface being insulated. At some tape movement stage the adhesive layer of the tape is heated, preferably, with a hot air flow. Following that the tape is pressed with its adhesive layer down to the preliminarily cleaned pipeline surface with an overlap with the previous tape wind and further pressed to the pipeline to remove air bubbles remaining between the tape and the pipeline surface. Following that the tape is thermoset, preferably, with a hot air flow. When the last wind is unwound from the coil, the shafts of the storage device start moving towards one another to release the stock of tape for winding onto the pipeline surface. In the meantime, the end of the tape of the spent coil is joined with the tape of the replacement roll using any technically convenient method. The joining either does not require stopping tape application onto the pipeline surface or requires stopping the process for 12 - 15 seconds only.

Preferably, NRL-ST60 450x2.0 two-layered tape with thermosetting base layer as per the TU 2293-001-29200582-02 and TU 2245-002-29200582-2007 Russian Standards is used for the process. During tape coil replacement. the end of the insulation tape of the spent coil is mechanically joined with the beginning of the insulation tape of the next coil by gluing thus providing for an almost uninterrupted winding process.

The insulation coating application unit is mounted on the pipeline using any known method, wherein the mounting method mainly depends on the additionally used equipment.

The unit for insulation coating application on long pipeline sections provided herein can be used as follows.

Before the commencement of the insulation coating application unit movement, the end of the tape preliminarily unwound from the replacement tape coil is drawn its adhesive layer outside through the storage device shafts and then through the outer side of the rolls, at the last roll it is turned its adhesive layer towards the pipeline being insulated, then drawn to the surface of the pipeline being insulated and finally fixed on the pipeline. Hot air supply from the unit is turned on for heating the adhesive layer. While the insulation coating application unit is moved along the pipeline the tape is unwound from the coil and simultaneously wound on the pipeline surface. The shafts of the storage device move apart from one another to provide a stock of tape. When the tape turned its heated adhesive layer towards the pipeline surface touches the pipeline surface, the tool for adhesive material spreading acts upon the tape at its outer side. The adhesive material is spread over the pipeline surface for filling any roughness on the pipeline surface and displacing the air from under the tape with the simultaneous retaining of the tape edge at the point of overlap with the previous tape wind and the application of tensile stress growing from the overlapping tape edge towards the opposite tape edge. Preferably, the tape edge is retained at the point of overlap with the previous tape wind by pressing it with elastic conical hubs, and the rotation axis is transverse to the tape edge. During pressure application to the outer tape surface the tape is tensioned to opposite sides from the tops of the conical hubs. Then the tape is thermoset with hot air or using a radiation method. When the last wind is unwound from the coil, the shafts of the storage device start moving towards one another to release the stock of tape and ensure uninterrupted thermal insulation application.

During tape coil replacement the end of the insulation tape of the spent coil is mechanically joined with the beginning of the insulation tape of the next coil. The full working cycle of the insulation coating application device provided herein provides for guaranteed air displacement from roughness on the pipeline surface and its simultaneous filling with the adhesive material and tight wrapping of the pipeline surface thus improving the quality of pipeline insulation.

By way of example, use of the technical solution provided herein in combination with the NRL-ST60 225x 1.8 thermoplastic two-layered tape as per the TU 2293-001-29200582-02 Russian Standard for insulating a 1420 mm diameter pipeline section provided a homogeneous and high-quality insulation coating with the cohesion tearing force from the polymer coating at the overlap point A_COh = 60- 65 N/cm and the cohesion tearing force from the preliminarily primed coated metallic surface A_coh = 70-75 N/cm.

Claims

What is claimed is a

1. Method of insulation application on the outer surface of pipelines comprising unwinding the insulation tape from a coil installed on a spool carrier, drawing the tape through the storage device, helically winding the tape onto the pipeline and retaining it on the pipeline and jointing a new tape coil once the current tape coil is spent, wherein the tape storage device is arranged between said spool carrier and the pipeline, the insulation tape is tape with adhesive material, during winding the tape that has passed the storage device is turned its adhesive side away from the pipeline, the unwound section of tape is heated at its adhesive side, the tape is turned its adhesive side to the pipeline, when the adhesive layer touches the pipeline surface the tape base is pressed down with a distributed load, the tape turned its adhesive side away from the pipeline is drawn along the rolls circularly arranged around the pipeline to be insulated at their exterior side relative to the pipeline, and the replacement tape coil is arranged parallel to the pipeline axis.

2. Method of Claim 1 wherein said insulation tape is thermosetting base tape.

3. Method of Claim 2 wherein the helically wound tape winds are evenly heated.

4. Method of Claim 1 wherein said pipeline surface is preliminarily coated with a primer layer.

5. Method of Claim 1 wherein during tape coil replacement, the end of the insulation tape of the spent coil is joined with the beginning of the insulation tape of the next coil.

6. Method of Claim 1 wherein insulation tape is wound onto preliminarily cleaned pipeline surface.

7. Method of Claim 1 wherein the unwound section of tape is heated to the plastic transition point of the adhesive material.

8. Method of Claim 1 wherein the adhesive material is spread for filling any roughness on the pipeline surface and displacing the air from under the tape with the simultaneous retaining of the tape edge at the point of overlap with the previous tape wind and the application of tensile stress growing from the overlapping tape edge towards the opposite tape edge.

9. Unit for applying insulation coating on pipelines comprising a case, at least two spool carriers for installing insulation tape coils, a tool for pressing the tape to the pipeline surface, a heater and a storage device wherein said unit allows using insulation tape one side of which has an adhesive layer, and said storage device is mounted between the case of said unit and said spool carriers, wherein said unit further comprises a system of tape guiding and unwinding rolls installed inside its case and a tool for spreading the heated adhesive material over the pipeline surface, and said system of rolls comprises at least six rolls oriented parallel to the pipeline axis and arranged circularly around the pipeline, further wherein the spool carrier of the currently unwound coil is oriented parallel to the axis of the pipeline being insulated during tape application.

10. Unit of Claim 9 wherein said tool for spreading the heated adhesive material comprises a shaft having a retaining roll for retaining the edge of the insulation tape wherein the working surface of said shaft is formed by elastic conical washers interchanging with chafing plates.

1 1. Unit of Claim 9 wherein said rolls are fixed.

12. Unit of Claim 9 wherein said rolls are capable of rotating about their longitudinal axis due to the movement of the drawn tape.

13. Unit of Claim 9 wherein said rolls are capable of forced movement.