WO2016095765A1

WO2016095765A1 - Pipeline joint coating structure and pipeline joint coating method therefor

Info

Publication number: WO2016095765A1
Application number: PCT/CN2015/097216
Authority: WO
Inventors: 郑明嘉; 雷小均; 胡兵; 苏俊业; 陈锬; 周浩; 杨智勇; 杨志骅; 何浏炜
Original assignee: 四川金发科技发展有限公司
Priority date: 2014-12-17
Filing date: 2015-12-12
Publication date: 2016-06-23

Abstract

A pipeline joint coating structure comprises an abutting steel tube (1), a two-end prefabricated anti-corrosive coating (2) circularly applied on the outer wall of the abutting steel tube, an epoxy primer layer (3) arranged on the outer wall of a welding joint reserved in the abutting steel tube, and a joint coating sheet (4) wrapped on the periphery of the primer layer. The joint coating sheet completely covers the epoxy primer layer and has two ends in lap joint with the prefabricated anti-corrosive coating. Also disclosed is a pipeline joint coating method, which comprises the steps of surface treatment, steel tube preheating, primer painting, joint coating sheet wrapping, silicon sheet heating, airbag pressurization, and pressure maintaining cooling. The present invention has good sealing effect, stable anti-corrosion property and long service life.

Description

Pipe filling mouth and pipe filling method thereof

Technical field

The invention belongs to the technical field of gas transmission and oil pipeline construction, and particularly relates to a pipeline filling method and a pipeline filling method thereof.

Background technique

The steel pipeline used in the construction of oil and gas pipelines must be pre-treated with anti-corrosion treatment. The 3LPE and 3LPP anti-corrosion coatings are commonly used anti-corrosion structures in pipeline anti-corrosion. In the pipeline anti-corrosion process, the welding joint is often reserved, and the width is generally 100-150mm. The corrosion protection of the welded joints of steel pipes is completed at the construction site. The pipe joint anti-corrosion technology used has a significant impact on the overall anti-corrosion effect of the pipeline, because it is related to the final anti-corrosion quality of the entire pipeline. Regardless of the quality of the 3LPE and 3LPP anti-corrosion coatings in the prefabricated factory, if the effect of the on-site filling is not good, the steel pipeline will be seriously corroded, the service life of the buried pipeline will be shortened, and even serious consequences such as leakage will occur.

The welded joints of 3LPE and 3LPP anticorrosive pipes are generally protected by heat shrink sleeves (bands). This traditional heat shrink sleeve repairing structure has the following disadvantages in use:

1. The hot-melt adhesive used in the heat shrinkable sleeve (belt) has strong polarity, low molecular weight, and poor compatibility with PE or PP on the surface of the prefabricated anti-corrosion layer at both ends, and the elastic shrinkage force of the cross-linked polyethylene substrate is not heated. Large, the pressure applied to the hot melt adhesive is limited, and the hot melt adhesive and the prefabricated anti-corrosion layer at both ends cannot form a reliable bond, and the debonding cracking phenomenon is likely to occur after the embedding, resulting in failure of the joint.

2. Radiation cross-linked polyethylene heat shrinkable tape (set) must be obtained through multiple processes such as extrusion molding, radiation crosslinking, expansion, cooling, and gluing. The cost is extremely high, and it cannot be recycled by thermoplastics. Caused certain damage.

Summary of the invention

In order to overcome the deficiencies of the above prior art, the object of the present invention is to provide a pipe joint with high bonding strength, stable long-term performance of the anti-corrosion structure, long service life and low cost.

Another object of the present invention is to provide a pipe filling method with simple process, convenient operation and high anti-corrosion performance.

The invention is achieved by the following technical solutions:

A pipe joint, comprising a butt steel pipe and a prefabricated anti-corrosion layer at both ends, wherein the two ends are prefabricated with an anti-corrosion layer An epoxy primer layer is disposed on the outer wall of the butt jointed steel pipe at the outer wall of the butt joint steel pipe, and the outer periphery of the epoxy primer layer is covered with a layer of patch, and the patch is covered by the ring. The oxygen primer layer and the two ends are overlapped with the prefabricated anticorrosive layers at both ends.

The invention replaces the existing heat shrinkable sleeve with a patch sheet. For the 3LPE anticorrosive layer, the material of the patch sheet may be a maleic anhydride grafted polyethylene copolymer or a graft of polyethylene and maleic anhydride. The mixture of the polyethylene copolymers preferably has an overall graft ratio of 0.15 wt% or more. For the 3LPP anti-corrosion layer, the material of the patch sheet may be a maleic anhydride grafted polypropylene copolymer or a mixture of polypropylene and maleic anhydride grafted polypropylene copolymer, and the overall grafting rate is 0.15. More than wt% is appropriate.

There is a circular arc-shaped groove in the middle of the width direction of the filler piece (in the axial direction of the pipe), and the deepest part of the groove is 1.0-2.0 mm, and the width is preferably 0-5 mm smaller than the width of the annular weld bead at the weld bead. The circular arc groove can close the steel pipe when the patch is wrapped, which improves the quality of the mouth.

The length of the flat portion in the width direction of the patch is the same as the minimum length of the bare steel tube at the welded joint, and the ends of the flat portion are uniform thinned regions, and the width of each end is preferably 50-100 mm. The length of the patch (in the circumferential direction of the pipe) is as short as 60 mm smaller than the circumference of the pipe, and the longest is 100 mm longer than the pipe circumference. The ends of the straight portion are also uniformly thinned, and the length of each end is 30- 60mm is suitable. The even thinning zone can make the patch and the prefabricated anti-corrosion layer at both ends and the self-bonding smooth, improve the quality of the mouth.

The thickness of the flat portion of the main body of the patch should be slightly larger than the thickness of the prefabricated anti-corrosion layer at both ends, and it is suitable to achieve 100-125% of the thickness of the pre-formed anti-corrosion layer at both ends.

A pipe filling method includes the following steps:

a. Surface treatment: decontamination and sand blasting of the surface of the steel pipe at the pipe joint;

b. Preheating of steel pipe: preheating the steel pipe at the pipe joint to 50-75 ° C;

c. Applying the primer: uniformly coating the epoxy primer on the entire surface of the steel pipe at the filling portion;

d. Patching of the patch: After the epoxy primer is dried, the patch is coated on the surface of the epoxy primer;

e. Silicone sheet heating: a silicone heating sheet is wrapped around the outer periphery of the patch sheet to heat the patch sheet;

f. Airbag pressurization: the outer circumference of the silicone heating sheet is pressed by the inflated airbag, and the outer circumference of the inflated airbag has a pressure-bearing steel sleeve, and the function is to restrain the airbag;

g. Pressure-maintaining cooling: the inflated airbag maintains a certain pressure, cut off the power supply of the silicone heating sheet, and slowly cool to Below 60 °C.

In the step a of the invention, after the surface of the steel pipe at the joint portion is sandblasted, the surface quality of the steel pipe should reach Sa2.5 level, and the surface of the steel pipe is cleaned with compressed air immediately after sandblasting and rust removal.

In the step b of the invention, a plurality of existing methods, such as electric heating, electromagnetic induction heating, infrared heating, liquefied gas flame heating, etc., can be used to preheat the steel pipe of the pipe joint to 50-75 ° C (using The calibrated infrared thermometer monitors the temperature, and the preheating temperature can be appropriately increased when the outside temperature is low. One of the purposes of heating is to remove the moisture adsorbed on the steel pipe, and the other is to facilitate the rapid drying of the epoxy primer.

In the step c of the present invention, according to the operation guide of the epoxy primer, the epoxy primer is uniformly brushed along the circumferential direction of the pipe to avoid air bubbles, and the epoxy primer is uniformly applied to the entire steel pipe at the filling portion. surface. If the temperature of the epoxy primer is too low and the coating is inconvenient, the epoxy primer can be heated appropriately.

In the step d of the present invention, the time required for the epoxy primer to dry on the surface is affected by the preheating temperature of the steel pipe and the ambient temperature. The lower the temperature, the longer the curing time, and the shorter the reverse. The dry time control is preferably 30-60 minutes.

Considering the influence of rain, snow and dust in the field construction, the patch sheet can be wrapped immediately after the epoxy primer is applied. After the epoxy primer is dry, the silicone heating sheet is energized to the specified temperature, thus avoiding The epoxy primer is contaminated while waiting for the surface to dry.

The invention replaces the existing heat shrinkable sleeve with a patch sheet. For the 3LPE anticorrosive layer, the material of the patch sheet may be a maleic anhydride grafted polyethylene copolymer or a graft of polyethylene and maleic anhydride. The mixture of the polyethylene copolymers may have a blending ratio of 8:1 to 2:1, and preferably has an overall graft ratio of 0.15% by weight or more. For the 3LPP anti-corrosion layer, the material of the patch sheet may be a maleic anhydride grafted polypropylene copolymer or a mixture of polypropylene and maleic anhydride grafted polypropylene copolymer, and the blending ratio may be 8 : 1-2:1, preferably the total graft ratio is 0.15 wt% or more.

There is a circular arc-shaped groove in the middle of the width direction of the patch (in the axial direction of the pipe), and the deepest portion of the groove is 1.0-2.0 mm, and the width is preferably 0-5 mm smaller than the width of the annular weld bead at the filling portion. The groove can make the sealing piece close to the steel pipe when it is wrapped, which is beneficial to the silicone heating piece always adhering to the filling sheet to improve the quality of the mouth.

The length of the flat portion in the width direction of the patch is the same as the minimum length of the bare steel tube at the welded joint, and the ends of the flat portion are uniform thinned regions, and the width of each end is preferably 50-100 mm. Patch length direction (along the tube The circumferential direction of the road) is as short as 60mm smaller than the circumference of the pipe, and the longest is 100mm longer than the circumference of the pipe. The ends of the straight part are also uniformly thinned, and the length of each end is 30-60mm. The uniform thinning zone can make the patch and the prefabricated anti-corrosion layer at both ends and the self-bonding smooth, which is beneficial to the silicone heating sheet always adhering to the patch sheet and improving the quality of the mouth.

When the length of the bare steel pipe at the weld is too large, the patch can be customized according to the length of the exposed steel pipe on both sides of the bead, so that the length of the straight portion on both sides of the groove of the patch is corresponding to it.

The thickness of the flat portion of the patch should be slightly larger than the thickness of the prefabricated anti-corrosion layer at both ends, and it is suitable to achieve 100-125% of the thickness of the straight-tube anti-corrosion layer.

When the patch is wrapped, it can be tightened with a tight rope device, etc., and then fixed with a fixing piece or a sticker, or it can be fixed by soldering iron.

In the step e of the invention, the silica gel heating sheet is heated by electric heating, on the one hand, the epoxy primer is quickly solidified, and on the other hand, the patch sheet is melted and chemically reacted with the epoxy primer in the curing process to form a firm bond. The heating temperature is controlled by a temperature sensor and a temperature controller, and the range is preferably 160-210 °C. The power of the silicone heating sheet should not be lower than 0.75 W/cm ² to ensure that the power is raised to the specified temperature within 3 minutes. Silica gel can work for a long time below 250 °C, and does not bond with the melted patch. In addition to silica gel, high temperature resistant materials such as fluororubber can also be used as the outer layer of the heating sheet.

In order to ensure a better bonding effect, the present invention applies an air bag to press the outer periphery of the silicone heating sheet with a pressure of 0.03-0.3 MPa. The airbag should be filled with gas and reach the specified pressure before the temperature of the patch is 60 °C. After the temperature and pressure reach the specified value, it should be kept for 10-30 minutes, and then transferred to the pressure-maintaining cooling stage.

In order to restrain the shape of the airbag and further ensure the pressure application effect, the present invention installs a pressure-bearing steel sleeve on the outer circumference of the inflatable airbag, and after the operation of the filling operation is completed, the pressure-bearing steel sleeve, the inflatable airbag, and the silicone heating sheet can be removed.

Compared with the prior art, the invention has the following advantages:

The invention adopts a patch sheet structure outside the epoxy primer layer, and the patch sheet itself maintains thermoplasticity, and can be completely melted and integrated with the prefabricated anti-corrosion layer layer at both ends and the patch joint itself, and the sealing effect is excellent, and the corrosion protection is excellent. The structure has long-term stable performance and long service life.

The invention adopts airbag pressurization, can exert great pressure on the patch sheet during softening and bonding process, and the patch sheet melts and chemically reacts with the epoxy primer in the curing process to form a firm bond, and the epoxy is greatly improved. The bonding strength of the primer layer can reach 250N/cm or more at 23° C., and the peel strength at 50° C. is 100 N/cm or more, which is twice and 5 times higher than that of the heat shrinkable sleeve (belt);

The patch of the invention does not need radiation crosslinking, and the cost is low, and the scrap can be recycled without polluting the environment.

DRAWINGS

1 is a schematic view of a pipe joint structure of the present invention

Among them, 1 butt joint steel pipe 2 prefabricated anti-corrosion layer 3 epoxy primer layer 4 patch.

detailed description

The invention is further illustrated by the following detailed description of the preferred embodiments of the invention, but the embodiments of the invention are not limited by the following examples.

As shown in Fig. 1, a 3LPE pipe joint of a Ф1219 includes a butt joint steel pipe 1 and a prefabricated anticorrosion layer 2 at both ends, and a prefabricated anticorrosion layer 2 at both ends is applied on the outer wall of the butt pipe 1, and the weld is reserved in the butt pipe 1. The outer wall of the mouth is provided with an epoxy primer layer 3, and the outer periphery of the epoxy primer layer 3 is covered with a patch sheet 4, and the patch sheet 4 is completely covered with the epoxy primer layer 3 and prefabricated at both ends and both ends. Layer 2 is overlapped.

The material of the patch sheet 4 was a maleic anhydride grafted polyethylene copolymer, the graft ratio was 0.25 wt%, and the thickness of the patch sheet 4 was 4.2 mm.

The length of the straight portion of the patch 4 along the axial direction of the pipe is the same as the minimum length of the exposed steel pipe at the welded joint, and the ends of the straight portion are uniformly thinned, each end having a width of 60 mm, and the patch 4 is along the circumferential direction of the pipe. The length of the straight portion is greater than 30 mm of the circumference of the pipe, and the ends of the straight portion are also uniformly thinned, and the length is 40 mm.

The patch piece 4 has a circular arc-shaped groove in the middle of the axial direction of the pipe, and the deepest portion of the groove is 2.0 mm, and the width thereof is 3 mm smaller than the width of the ring-shaped weld bead at the welded joint.

The method for repairing a pipe of the present invention comprises the following steps in sequence:

a. Surface treatment: decontamination and sandblasting and descaling the surface of the steel pipe in the pipe joint part, so that the surface quality of the steel pipe reaches Sa2.5 level, and then the surface of the steel pipe is cleaned with compressed air after derusting;

b. Preheating of steel pipe: The electric steel pipe is preheated to 50-75 °C by electric heating, and the temperature is monitored by a verified infrared thermometer. When the external temperature is low, the preheating temperature can be appropriately increased.

d. Patching of the patch: After 45 minutes, the epoxy primer is dry, and the surface of the epoxy primer is covered with a patch. The thickness of the patch sheet was 4.2 mm, and the material was a maleic anhydride grafted polyethylene copolymer, and the graft ratio was 0.25 wt%. There is a circular arc-shaped groove in the middle of the width direction of the patch (in the axial direction of the pipe), the depth of the groove is 2.0mm, and the width is 3mm smaller than the width of the annular weld bead at the weld; the straight part of the width of the patch is The length is the same as the minimum length of the exposed steel pipe at the welded joint, and the ends of the straight part are uniformly thinned, each end has a width of 60mm; the length of the straight section of the patch (in the circumferential direction of the pipe) is less than the circumference of the pipe by 30mm. The ends of the straight portion are also uniformly thinned, each end having a length of 60 mm;

e. Silicone sheet heating: a silicone heating sheet is wrapped around the outer periphery of the patch sheet, and the patch sheet is heated to melt, and the heating temperature is controlled at 180 ° C - 200 ° C for 20 min;

f. Airbag pressurization: the outer circumference of the silicone heating sheet is pressed by the inflated airbag, the pressure is controlled to be 0.15 MPa; the outer circumference of the inflated airbag has a pressure-bearing steel sleeve, and the function is to restrain the airbag;

g. Pressure-maintaining cooling: Inflate the airbag to maintain the pressure of 0.15MPa, cut off the power supply of the silicone heating sheet, and slowly cool it to below 50 °C. After the operation of the filling operation is completed, the pressure-bearing steel sleeve, the inflatable airbag and the silicone heating sheet can be removed. The evaluation results are shown in Table 1.

Example 2:

A 3LPP pipeline filling method of the Ф610 includes the following steps in sequence:

b. Preheating of steel pipe: The steel pipe of the pipe joint part is preheated to 50-75 °C by electromagnetic induction heating, and the temperature is monitored by a verified infrared thermometer. When the external temperature is low, the preheating temperature can be appropriately increased.

d. Patching of the patch: After 30 minutes, the epoxy primer is dry, and the patch is coated on the surface of the epoxy primer. The patch sheet 4 has a thickness of 3.0 mm and is a 4:1 blend of polypropylene and maleic anhydride grafted polypropylene copolymer. There is a circular arc-shaped groove in the middle of the width direction of the mouth piece 4 (in the axial direction of the pipe), the deepest part of the groove is 1.5 mm, and the width thereof is 2 mm smaller than the width of the ring-shaped weld bead at the welded joint. The length of the straight portion of the width of the patch The length of the bare steel pipe at the weld joint is the same, the two ends of the flat portion are uniformly thinned, and the width of each end is 80mm; the length of the straight part of the length of the patch (in the circumferential direction of the pipe) is greater than the circumference of the pipe by 50mm. The ends of the straight portion are also uniform thinning zones, each end having a length of 50 mm;

e. Silicone sheet heating: a silicone heating sheet is wrapped around the outer periphery of the patch sheet, and the patch sheet is heated to melt, and the heating temperature is controlled at 190 ° C - 210 ° C for 15 min;

f. Airbag pressurization: the outer circumference of the silicone heating sheet is pressed by the inflated airbag, the pressure is controlled to be 0.08 MPa; the outer circumference of the inflated airbag has a pressure-bearing steel sleeve, and the function is to restrain the airbag;

g. Pressure-maintaining cooling: Inflate the airbag to maintain a pressure of 0.08MPa, cut off the power supply of the silicone heating sheet, and slowly cool it to below 60 °C. After the filling operation is completed, the pressure-bearing steel sleeve, the inflatable airbag, and the silicone heating sheet can be removed. The evaluation results are shown in Table 1.

Comparative example 1:

A pipe filling method includes the following steps in sequence:

a. Surface treatment: decontaminating, sandblasting and derusting the surface of the steel pipe in the pipe joint part, so that the surface quality of the steel pipe reaches Sa2.5 level, and then the surface of the steel pipe is cleaned with compressed air after rust removal;

b. Surface preheating: The surface of the steel pipe in the pipe joint part is preheated to 50-75 °C by electromagnetic induction heating, and the temperature is monitored by a verified infrared thermometer. When the outside temperature is low, the preheating temperature can be appropriately increased;

d. Heat shrink sleeve repair: the heat shrink sleeve is wrapped to the filling portion, and the heat shrink sleeve is heated by the intermediate frequency heater, and the heating temperature is 140-160 ° C, so that the heat shrink sleeve shrinks and wraps to the filling portion. The filling operation is completed, and the results of the effect evaluation are shown in Table 1.

Table 1 shows the evaluation results of the effects of the joints of the respective examples and the comparative pipes.

Test criteria or methods:

Peel strength: GB/T 23257-2009;

Sealing effect: GB/T 3257-2009.

Claims

A pipe joint comprising a butt pipe (1) and a prefabricated anticorrosive layer (2) at both ends, wherein the prefabricated anticorrosive layer (2) is applied to the outer wall of the butt pipe (1), characterized in that the butt pipe is (1) An epoxy primer layer (3) is disposed on the outer wall of the reserved solder joint, and the outer periphery of the epoxy primer layer (3) is covered with a layer of patch (4), the patch (4) All of the epoxy primer layer (3) is covered and the two ends are overlapped with the prefabricated anticorrosive layer (2) at both ends.
The pipe fitting according to claim 1, wherein for the 3LPE anticorrosive layer, the material of the patch (4) is maleic anhydride grafted polyethylene copolymer or polyethylene and maleic anhydride grafted polymer. a mixture of ethylene copolymers; for the 3LPP coating, the material of the patch (4) is a maleic anhydride grafted polypropylene copolymer or a mixture of polypropylene and maleic anhydride grafted polypropylene copolymer; The overall graft ratio of the material of the sheet (4) was 0.15 wt% or more.
The pipe fitting according to claim 1, wherein the filler piece (4) has a circular arc-shaped groove in the middle of the axial direction of the pipe, and the groove is at the deepest point of 1.0-2.0 mm, and the width ratio is welded. The width of the ring bead at the mouth is 0-5mm.
The pipe fitting according to claim 3, wherein the length of the straight portion of the patch (4) along the axial direction of the pipe is the same as the minimum length of the bare steel pipe at the welded joint, and the ends of the straight portion are Uniform thinning zone, each end width is 50-100mm; the straight section of the length of the patch (4) is 60mm smaller than the circumference of the pipe, the longest is 100mm longer than the pipe circumference, and the ends of the straight part are evenly thinned. The area is 30-60mm in length.
The pipe fitting according to claim 1, characterized in that the thickness of the straight portion of the body of the mouth piece (4) is 100-125% of the thickness of the pre-formed anti-corrosion layer (2) at both ends.
A pipe filling method, characterized in that the method comprises the following steps:

a. Surface treatment: decontamination and sand blasting of the surface of the steel pipe at the pipe joint;

b. Preheating of steel pipe: preheating the steel pipe at the pipe joint to 50-75 ° C;

c. Applying the primer: uniformly coating the epoxy primer on the entire surface of the steel pipe at the filling portion;

d. Patching of the patch: After the epoxy primer is dried, the patch is coated on the surface of the epoxy primer;

e. Silicone sheet heating: a silicone heating sheet is wrapped around the outer periphery of the patch sheet to heat the patch sheet;

f. Airbag pressurization: the outer circumference of the silicone heating sheet is pressed by the inflated airbag, and the outer circumference of the inflated airbag has a pressure-bearing steel sleeve;

g. Pressure-maintaining cooling: The inflated airbag maintains a certain pressure, cut off the power supply of the silicone heating sheet, and slowly cool to below 60 °C.
The pipe filling method according to claim 6, wherein in the step b, the preheating mode is electric heating jacket heating, electromagnetic induction heating, infrared heating or liquefied gas flame heating.
The pipe filling method according to claim 6, wherein for the 3LPE anticorrosive layer, the material of the patch is maleic anhydride grafted polyethylene copolymer or polyethylene and maleic anhydride grafted polyethylene copolymerized. a mixture of materials; for the 3LPP anti-corrosion layer, the material of the patch is maleic anhydride grafted polypropylene copolymer or a mixture of polypropylene and maleic anhydride grafted polypropylene copolymer; The branch rate reached 0.15 wt% or more.
The pipe filling method according to claim 6, wherein the patch has a circular arc-shaped groove in the middle of the width direction, and the groove has a width of 1.0-2.0 mm at the deepest portion, and the width is larger than the ring-shaped weld bead at the filling portion. The width is small 0-5mm.
The method of repairing a pipe according to claim 9, wherein the length of the flat portion in the width direction of the patch is the same as the minimum length of the steel pipe at the joint portion, and the ends of the straight portion are uniformly thinned regions. The width of each end is 50-100mm; the shortest part of the length of the patch is 60mm smaller than the circumference of the pipe, and the longest is 100mm longer than the circumference of the pipe. The ends of the straight part are also uniformly thinned, each length is 30 -60mm.
The pipe filling method according to claim 9, wherein the thickness of the flat portion of the patch is 100-125% of the thickness of the prefabricated coating at both ends.
The pipe filling method according to claim 6, wherein in the step d, the epoxy primer has a surface dry time of 30 to 60 minutes.
The pipe filling method according to claim 6, wherein in the step e, the heating temperature is 160-210 ° C and the time is 10-30 min.
The pipe filling method according to claim 6, wherein in the step f, the pressure applied is 0.03-0.3 MPa.