CN112361127A - On-site joint coating process for directly-buried heat-insulating pipeline - Google Patents
On-site joint coating process for directly-buried heat-insulating pipeline Download PDFInfo
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- CN112361127A CN112361127A CN202011157916.XA CN202011157916A CN112361127A CN 112361127 A CN112361127 A CN 112361127A CN 202011157916 A CN202011157916 A CN 202011157916A CN 112361127 A CN112361127 A CN 112361127A
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- joint
- pipe
- heat
- outer protective
- protection pipe
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L59/00—Thermal insulation in general
- F16L59/02—Shape or form of insulating materials, with or without coverings integral with the insulating materials
- F16L59/028—Composition or method of fixing a thermally insulating material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/10—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using hot gases (e.g. combustion gases) or flames coming in contact with at least one of the parts to be joined
- B29C65/103—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using hot gases (e.g. combustion gases) or flames coming in contact with at least one of the parts to be joined direct heating both surfaces to be joined
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/18—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools
- B29C65/20—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools with direct contact, e.g. using "mirror"
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
- B29C65/18—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated tools
- B29C65/22—Heated wire resistive ribbon, resistive band or resistive strip
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/01—General aspects dealing with the joint area or with the area to be joined
- B29C66/02—Preparation of the material, in the area to be joined, prior to joining or welding
- B29C66/022—Mechanical pre-treatments, e.g. reshaping
- B29C66/0222—Mechanical pre-treatments, e.g. reshaping without removal of material, e.g. cleaning by air blowing or using brushes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/01—General aspects dealing with the joint area or with the area to be joined
- B29C66/02—Preparation of the material, in the area to be joined, prior to joining or welding
- B29C66/022—Mechanical pre-treatments, e.g. reshaping
- B29C66/0224—Mechanical pre-treatments, e.g. reshaping with removal of material
- B29C66/02245—Abrading, e.g. grinding, sanding, sandblasting or scraping
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L59/00—Thermal insulation in general
- F16L59/14—Arrangements for the insulation of pipes or pipe systems
- F16L59/16—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like
- F16L59/165—Repairing insulated pipes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L59/00—Thermal insulation in general
- F16L59/14—Arrangements for the insulation of pipes or pipe systems
- F16L59/16—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like
- F16L59/18—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like adapted for joints
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L59/00—Thermal insulation in general
- F16L59/14—Arrangements for the insulation of pipes or pipe systems
- F16L59/16—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like
- F16L59/22—Arrangements specially adapted to local requirements at flanges, junctions, valves or the like adapted for bends
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2023/00—Tubular articles
Abstract
The invention provides a field joint coating process for a direct-buried heat-insulating pipeline, comprising the following steps of S1, digging and arranging a working room; s2, butting the outer surface of the steel pipe at the joint position and the heat-preservation outer protective pipe at the joint position; s3, preparing a joint outer protective pipe matched with the outer diameter of the heat-preservation outer protective pipe; s4, polishing areas to be welded on two sides of the inner surface of the outer protective pipe of the joint by using gauze; s5, respectively lapping the areas to be welded to the periphery of one end of the heat-preservation outer protective pipe; s6, determining the installation positions of the heating wires through the outer edges of the two sides of the outer protecting pipe of the joint; s7, switching on an electrothermal welding machine to weld the area to be welded; s8, performing extrusion welding on the second end of the outer protection pipe of the joint and the first end of the outer protection pipe of the joint; s9, carrying out a tightness test; s10, foaming of the filling joint; and S11, plugging the material injection hole and the exhaust hole. The invention relates to a field joint coating process for a directly-buried heat-insulating pipeline, aiming at ensuring that the heat-insulating joint coating engineering result strictly meets the standard requirement and the operation standard is unified.
Description
Technical Field
The invention belongs to the technical field of heat-insulating pipeline construction, and particularly relates to an on-site joint coating process for a directly-buried heat-insulating pipeline.
Background
With the increasingly reduced and growing demand of world energy sources, energy conservation, emission reduction and environmental protection become global development trends, and the governments of the country and various regions also advocate the development, application and industrialization of energy conservation, emission reduction and environmental protection products. In recent years, with the rapid development of the building energy-saving market in China, polyurethane rigid foam heat-insulating products are widely applied to the field of petroleum conveying pipelines and become one of the heat-insulating energy-saving products leading to the market. Meanwhile, along with the gradual increase of the conveying distance of an oil conveying pipe network, the conveying pipeline is influenced by external factors more and more, sometimes the oil conveying pipe network needs to bypass barriers or avoid some important facilities, or passes through a certain relay device, and thus specific requirements are provided for the bent pipe fitting of the heat preservation pipeline. The polyurethane direct-buried heat-insulating pipe is also called pipe-in-pipe, and is formed by two steps, and is composed of a high-density polyethylene outer protective layer, a polyurethane rigid foam plastic pipe and a steel pipe. The material of the heat-insulating layer has the density of 60kg/m3To 80kg/m3The rigid polyurethane foam fully fills the gap between the steel pipe and the sleeve pipe, and has certain bonding strength, so that the steel pipe, the outer sleeve pipe and the heat-insulating layer form a firm whole. The polyurethane directly-buried insulating pipe foam has good mechanical property and thermal insulationThe polyurethane foaming thermal insulation pipe can be widely used for liquid and gas conveying pipe networks, chemical pipeline thermal insulation engineering petroleum, chemical, central heating and heating networks, central air conditioning ventilation pipelines, municipal engineering and the like.
The steel pipeline used in the construction of the oil and gas transmission pipeline must be subjected to anticorrosion treatment in advance, and the 3LPE and 3LPP anticorrosion layers are anticorrosion structures commonly adopted in the anticorrosion of the outside of the pipeline. The corrosion prevention of the welded joint of the steel pipeline is finished on a construction site, and the adopted pipeline joint coating corrosion prevention technology has great influence on the overall corrosion prevention effect of the pipeline, because the corrosion prevention technology is related to the final corrosion prevention quality of the whole pipeline. No matter how good the quality of 3LPE and 3LPP anticorrosive coatings in a prefabricated factory is, if the on-site joint coating effect is not good, the steel pipeline can be seriously corroded, the service life of the buried pipeline is shortened, and even serious consequences such as leakage are caused.
Disclosure of Invention
In view of the above, the present invention is directed to a field joint coating process for a directly buried heat insulation pipeline, which aims to ensure that the heat insulation joint coating engineering result strictly meets the standard requirement and the operation standard is unified.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
an in-situ joint coating process for a directly buried insulated pipeline, comprising the following steps: s1, digging a layout operation room with two adjacent direct-buried heat insulation pipeline heat insulation joints, wherein each heat insulation pipeline comprises a steel pipe and a heat insulation layer and a heat insulation outer protective pipe which are sequentially sleeved on the periphery of the steel pipe, and the end faces of the steel pipes of the two adjacent heat insulation pipelines are fixedly connected; s2, cleaning the outer surface of the steel pipe at the joint position and the heat-preservation outer protecting pipe at the joint position; s3, preparing a joint outer protection pipe matched with the outer diameter of the heat-preservation outer protection pipe, wherein the joint outer protection pipe is in a rectangular structure in a conventional state, a first end of the joint outer protection pipe is fixed in a working state, and a second end of the joint outer protection pipe extends along the periphery of the heat-preservation outer protection pipe until the second end of the joint outer protection pipe is lapped to the first end of the joint outer protection pipe, so that a hollow tubular structure is formed; s4, cleaning the outer surface of the outer protection pipe of the joint, and polishing the areas to be welded on the two sides of the inner surface of the outer protection pipe of the joint by using gauze; s5, overlapping the two to-be-welded areas of the outer protective pipe of the joint to the peripheries of one ends of two adjacent heat-preservation outer protective pipes respectively and fixing the relative positions by tightening belts; s6, determining the installation positions of the heating wires through the outer edges of the two sides of the outer protecting pipe of the joint, cutting avoidance holes on the pipe walls of the two ends of the outer protecting pipe of the joint, and then loosening the upper tightening belt, wherein the installation positions of the heating wires are respectively arranged on the periphery of one ends of the two heat-preservation outer protecting pipes; s7, respectively installing heating wires at the installation positions of the two heating wires, resetting the outer protective pipes of the joints to the positions in the step 5, enabling the positive electrode and the negative electrode of each heating wire to penetrate through one avoidance hole and be connected to an electric melting welding machine, and switching on the electric melting welding machine to respectively weld the two areas to be welded to the peripheries of one ends of the two adjacent heat-preservation outer protective pipes; s8, performing extrusion welding on the second end of the outer protection pipe of the joint and the first end of the outer protection pipe of the joint, and forming a material injection hole and an exhaust hole on the side wall of the outer protection pipe of the joint; s9, injecting pressure into the outer protective pipe of the butt joint through the material injection hole, and carrying out tightness test; s10, filling joint foaming between the periphery of the steel pipe and the outer protective pipe of the joint; s11, cleaning the outer surface of the outer protective pipe of the joint, and plugging the material injection hole and the exhaust hole.
Furthermore, in the step 1, the distance between the periphery of the outer protecting pipe and the bottom of the laying operation chamber is not less than 0.5m, and the distance between the end faces of two adjacent outer protecting pipes is not less than 0.4 m.
Further, the treatment method of the heat-preservation outer protection pipe in the step 2 is to firstly perform surface preparation by a mechanical cleaning method and an industrial alcohol method, wherein the cleaning range is 200mm outside the edge of the installation position of the joint outer protection pipe to the whole circumference range of the pipe end, and then perform gauze polishing treatment at the cleaning position.
Further, the length of the joint outer protecting pipe in a normal state is H1, the radius of the heat-preservation outer protecting pipe is R, and H1 is 3.14 × 2R +100 mm.
Further, the method for testing the stringency in step 9 comprises the following steps; a1, measuring the temperature of the outer protective pipe of the joint and the steel pipe; a2, the temperature of the outer protective pipe of the joint and the temperature of the steel pipe are all below 40 ℃, and a pressure gauge is arranged in the exhaust hole; and A3, inflating the space between the outer protective pipe of the joint and the steel pipe through the material injection hole, wherein the test pressure is 0.02Mpa, and the pressure is maintained for 2 min.
Furthermore, the material of the joint foam is PUR polyurethane, and the use temperature range of the joint foam is 15-45 ℃.
Further, the method for blocking the material injection hole and the vent hole in the step 9 is to expand the material injection hole and the vent hole into tapered holes by using a tapered drill, and then to respectively hot press a tapered rubber plug to the material injection hole and the vent hole, wherein the hot pressing temperature is not higher than 255 ℃.
Compared with the prior art, the on-site joint coating process for the directly buried heat-insulating pipeline has the following advantages:
(1) the on-site joint coating process for the directly-buried heat-insulating pipeline, disclosed by the invention, is used for performing heat-insulating joint coating on joints among heat-insulating pipelines or joints between the heat-insulating pipelines and heat-insulating pipe fittings and joints between the heat-insulating pipe fittings and the pipe fittings in a centralized heat supply or cold supply pipeline construction project, has strong universality, meets the on-site construction requirements of pipe fittings such as a tee joint, an elbow, a reducing pipe, an end cap and the like, and is standardized in operation.
(2) The on-site joint coating process for the directly-buried heat-insulating pipeline, disclosed by the invention, is used for automatically controlling the electric hot melting welding connection and the manual extrusion welding of the outer protective pipe of the on-site heat-insulating joint and foaming hole plugging of polyurethane rigid foam in the heat-insulating joint, and has the advantages of long design service life and high reliability.
Detailed Description
It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.
The terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The present invention will be described in detail with reference to examples.
An in-situ joint coating process for a directly buried insulated pipeline, comprising the following steps:
s1, digging a layout operation room with two adjacent direct-buried heat insulation pipeline heat insulation joints, wherein the distance between the periphery of the outer protective pipe and the bottom of the layout operation room is not less than 0.5m, and the distance between the end faces of the two adjacent outer protective pipes is not less than 0.4m, so as to ensure that the operation conditions can be met, the heat insulation pipeline comprises a steel pipe, a heat insulation layer and a heat insulation outer protective pipe, wherein the peripheries of the steel pipe and the heat insulation outer protective pipe are sequentially sleeved, and the end faces of the steel pipe of the two adjacent heat insulation pipelines are fixedly.
S2, firstly, mechanically cleaning the steel pipe at the joint position to remove hard and hard attachments adhered to the surface of the steel pipe, then removing fine dust and grease on the surface of the steel pipe by using industrial alcohol, and then removing rust by using gauze, wherein if the surface of the steel pipe needs to be coated with a coating, an installer needs to complete coating according to the requirements of a layer operation instruction;
the method comprises the steps of firstly, carrying out surface preparation on the joint position of the outer protective pipe of the heat-insulating pipe by a mechanical cleaning method and an industrial alcohol cleaning method, wherein the cleaning range is from 200mm to the whole circumference range of the pipe end beyond the edge of the installation position of the outer protective pipe of the joint, then, polishing by using an abrasive cloth (60-80 meshes are recommended), and if welding operation cannot be started within 20 minutes after cleaning and polishing, polishing the welding area again before the welding operation.
S3, preparing a joint outer protecting pipe matched with the outer diameter of the heat-preservation outer protecting pipe, wherein the joint outer protecting pipe is of a rectangular structure in a conventional state, the length size of the joint outer protecting pipe refers to the circumferential coating length in an operation installation state, the length of the joint outer protecting pipe in the conventional state is H1, the radius of the heat-preservation outer protecting pipe is R, the calculation method is that H1 is 3.14 × 2R +100mm, and each side of the joint outer protecting pipe is a straight side;
when the connector outer protection pipe is in a working state, the first end of the connector outer protection pipe is fixed, and the second end of the connector outer protection pipe extends along the periphery of the heat-preservation outer protection pipe until the second end of the connector outer protection pipe is lapped to the first end of the connector outer protection pipe, so that a hollow tubular structure is formed;
s4, the surface of the outer protection pipe of the joint is cleaned by mechanical and industrial alcohol, the inner surface of the outer protection pipe of the joint is completely and thoroughly cleaned by the industrial alcohol, and the welding area of the inner surface of the outer protection pipe of the joint is polished by abrasive cloth. If the outer protective pipe welding operation cannot be carried out within 20 minutes after the polishing operation, the inner surface welding area of the outer protective pipe of the joint is required to be fully polished again, and the purpose of polishing the inner surface welding area of the outer protective pipe of the joint by adopting abrasive cloth is to completely remove an oxide layer on the surface of a material in the welding area;
before the outer protective pipe of the joint is closed, the inner surface of the outer protective pipe of the joint below the pipeline is cleaned again by using industrial alcohol, and foreign matters affecting the welding result, such as sundries, gravel and the like, are removed. The cleaning work before the joint outer protective pipe is closed is crucial, the welding quality between the joint outer protective pipe and the pipeline outer protective pipe can be prevented from being influenced by foreign matters, and the welding defect below the pipeline is avoided
S5, selecting a proper Kevlar tightening belt according to the outer diameter of an operation pipeline to be installed on a welding tightener, respectively lapping two to-be-welded areas of the joint outer protective pipe to the periphery of one end of two adjacent heat-preservation outer protective pipes, fixing the relative position through the tightening belt, and closing the joint outer protective pipe by adopting two modes aiming at different conditions: when the wall thickness of the outer protective pipe of the joint is smaller than 8mm, the outer protective pipe of the area outside the tool is closed in a lap joint mode, the outer protective pipe of the area outside the tool is closed in a butt joint mode under other conditions, and when the heat-preservation joint coating with the overlong size is closed in the butt joint mode, a support bar is installed at the corresponding position of a closed seam, and the support bar is made of high-density polyethylene.
S6, cleaning the outer protective pipes of the heat-insulating pipes and the outer protective pipes of the joints and polishing the welding surfaces of the outer protective pipes to finish surface preparation before welding, determining the installation positions of the heating wires by the outer edges of the two sides of the outer protective pipes of the joints, marking the heating wires by using white mark lines, cutting off avoiding holes on the pipe walls of the two ends of the outer protective pipes of the joints, loosening and tightening the belts, wherein the installation positions of the heating wires are respectively arranged on the peripheries of one ends of the two outer protective pipes of the heat-;
s7, respectively installing heating wires at the installation positions of the two heating wires, wherein the heating wires are required to be suitable for electric hot melting welding, the type of an electric hot melting welding machine is mitel tsc6.0, resetting the joint outer protective pipes to the position in the step 5, enabling the positive electrode and the negative electrode of each heating wire to penetrate through one avoidance hole and be connected to the electric hot melting welding machine, and switching on the electric hot melting welding machine to respectively weld the two areas to be welded to the peripheries of one ends of the two adjacent heat preservation outer protective pipes;
s8, removing the exposed end of the heating net by using a tool cutter or a scraper, performing slope forming treatment in an extrusion welding operation area, before the slope forming operation needs to be paid attention, firstly adjusting the depth of the groove of a groove machine, ensuring that the milling cutter of the groove machine cannot penetrate through the whole wall thickness of an outer protective pipe of a joint, leaving a 2mm truncated edge at the bottom of the groove, and adopting a Leister Weldplst S2 manual extrusion welding machine for extrusion welding;
firstly, a hot air nozzle of a manual extrusion welding machine is used for preheating a welding surface along a welding seam, an included angle of about 80 degrees is formed between the extrusion welding machine and the welding surface by adjusting the angle before welding, a welding gun is moved at a constant speed along the welding seam in the welding process, the molten welding flux filled in the welding area is confirmed to fully fill the welding area, and the shape of the welding bead is smooth, uniform and slightly higher. After the extrusion welding process is finished, the welding process of the outer protective pipe of the joint is finished;
a20 mm flat drill bit is adopted to open a hole right above the top of the outer protective pipe of the joint, the drill bit is kept perpendicular to the surface of a drilled object in the hole opening process, shaking is avoided, and a material injection hole and an exhaust hole are formed.
And S9, confirming that the air source is normally connected, setting the airtight test pressure to 20kPa (0.2bar), maintaining the test pressure, spraying all welding seam areas with soapy water, carefully checking whether gradually-enlarged bubbles are generated, wherein the gradually-enlarged bubbles mean that leakage exists at the welding seam area, and particularly paying special attention to the fact that visual inspection of the welding seam at the position of the bottom of the pipeline should not be omitted.
S10, filling joint foam between the periphery of the steel pipe and the outer protective pipe of the joint, wherein the joint foam is made of PUR polyurethane, and the use temperature range of the joint foam is 15-45 ℃.
S11, cleaning the outer surface of the outer protective pipe of the joint, plugging the material injection hole and the exhaust hole, wherein the material injection hole and the exhaust hole are plugged by expanding the material injection hole and the exhaust hole into conical holes by using a conical drill bit, and then hot-pressing a conical rubber plug to the material injection hole and the exhaust hole respectively, wherein the hot-pressing temperature is not higher than 255 ℃.
The method for testing the stringency in the step 9 comprises the following steps; a1, measuring the temperature of the outer protective pipe and the steel pipe of the joint; a2, the temperature of the outer protective pipe of the joint and the temperature of the steel pipe are all below 40 ℃, and a pressure gauge is arranged in the exhaust hole; and A3, inflating the space between the outer protective pipe of the joint and the steel pipe through the material injection hole, wherein the test pressure is 0.02Mpa, and the pressure is maintained for 2 min.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (7)
1. An on-site joint coating process for a directly-buried heat-insulating pipeline is characterized by comprising the following steps: comprises the following steps;
s1, digging a layout operation room with two adjacent direct-buried heat insulation pipeline heat insulation joints, wherein each heat insulation pipeline comprises a steel pipe and a heat insulation layer and a heat insulation outer protective pipe which are sequentially sleeved on the periphery of the steel pipe, and the end faces of the steel pipes of the two adjacent heat insulation pipelines are fixedly connected;
s2, cleaning the outer surface of the steel pipe at the joint position and the heat-preservation outer protecting pipe at the joint position;
s3, preparing a joint outer protection pipe matched with the outer diameter of the heat-preservation outer protection pipe, wherein the joint outer protection pipe is in a rectangular structure in a conventional state, a first end of the joint outer protection pipe is fixed in a working state, and a second end of the joint outer protection pipe extends along the periphery of the heat-preservation outer protection pipe until the second end of the joint outer protection pipe is lapped to the first end of the joint outer protection pipe, so that a hollow tubular structure is formed;
s4, cleaning the outer surface of the outer protection pipe of the joint, and polishing the areas to be welded on the two sides of the inner surface of the outer protection pipe of the joint by using gauze;
s5, overlapping the two to-be-welded areas of the joint outer protective pipes to the peripheries of one ends of two adjacent heat-preservation outer protective pipes respectively and fixing the relative positions through tightening belts;
s6, determining installation positions of heating wires through the outer edges of the two sides of the outer protecting pipe of the joint, cutting avoidance holes in the pipe walls of the two ends of the outer protecting pipe of the joint, and then loosening the upper tightening belt, wherein the installation positions of the heating wires are respectively arranged on the periphery of one ends of the two heat-preservation outer protecting pipes;
s7, respectively installing heating wires at the installation positions of the two heating wires, resetting the outer protective pipes of the joints to the positions in the step 5, enabling the positive electrode and the negative electrode of each heating wire to penetrate through one avoidance hole and be connected to an electric melting welding machine, and switching on the electric melting welding machine to respectively weld the two areas to be welded to the peripheries of one ends of the two adjacent heat-preservation outer protective pipes;
s8, performing extrusion welding on the second end of the joint outer protection pipe and the first end of the joint outer protection pipe, and forming a material injection hole and an exhaust hole in the side wall of the joint outer protection pipe;
s9, injecting pressure into the outer protective pipe of the butt joint through the material injection hole, and carrying out tightness test;
s10, filling joint foaming between the periphery of the steel pipe and the outer protective pipe of the joint;
s11, cleaning the outer surface of the outer protective pipe of the joint, and plugging the material injection hole and the exhaust hole.
2. The in-situ patching process for a buried insulated pipeline according to claim 1, wherein: in the step 1, the distance between the periphery of the outer protecting pipes and the bottom of the laying operation chamber is not less than 0.5m, and the distance between the end faces of two adjacent outer protecting pipes is not less than 0.4 m.
3. The in-situ patching process for a buried insulated pipeline according to claim 1, wherein: the treatment method of the heat-preservation outer protection pipe in the step 2 is that firstly, surface preparation is carried out through a mechanical cleaning method and an industrial alcohol method, the cleaning range is 200mm beyond the edge of the installation position of the joint outer protection pipe to the whole circumference range of the pipe end, and then gauze polishing treatment is carried out at the cleaning position.
4. The in-situ patching process for a buried insulated pipeline according to claim 1, wherein: the length of the joint outer protective pipe in a normal state is H1, the radius of the heat-preservation outer protective pipe is R, and H1 is 3.14 x 2R +100 mm.
5. The in-situ patching process for a buried insulated pipeline according to claim 1, wherein: the method for testing the stringency in the step 9 comprises the following steps;
a1, measuring the temperature of the outer protective pipe and the steel pipe of the joint;
a2, the temperature of the outer protective pipe of the joint and the temperature of the steel pipe are all below 40 ℃, and a pressure gauge is arranged in the exhaust hole;
and A3, inflating the space between the outer protective pipe of the joint and the steel pipe through the material injection hole, wherein the test pressure is 0.02Mpa, and the pressure is maintained for 2 min.
6. The in-situ patching process for a buried insulated pipeline according to claim 1, wherein: the material of the joint foam is PUR polyurethane, and the use temperature range of the joint foam is 15-45 ℃.
7. The in-situ patching process for a buried insulated pipeline according to claim 1, wherein: and in the step 9, the method for blocking the material injection hole and the exhaust hole comprises the steps of expanding the material injection hole and the exhaust hole into conical holes by using a conical drill, and then respectively hot-pressing a conical rubber plug to the material injection hole and the exhaust hole, wherein the hot-pressing temperature is not higher than 255 ℃.
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Cited By (1)
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| CN114216001A (en) * | 2021-11-24 | 2022-03-22 | 中投(天津)智能管道股份有限公司 | Heat insulation construction process suitable for directional drilling crossing section heat insulation pipeline interface in high and cold area |
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Application publication date: 20210212 |