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CN-122014926-A - Interface-enhanced rubber ring electric-melting steel skeleton polyethylene composite pipe and preparation method and application thereof

CN122014926ACN 122014926 ACN122014926 ACN 122014926ACN-122014926-A

Abstract

The invention discloses an interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe and a preparation method and application thereof, and belongs to the technical field of pipelines. The invention introduces polar functional groups on the surface of the inner high-density polyethylene layer through plasma activation to form chemical bonding with the interface reinforcing bonding layer, adopts copper-plated steel wires coated with nano silicon dioxide modified epoxy resin on the surface to wind to form a steel skeleton reinforcing layer, realizes physical interlocking and chemical reaction with the interface reinforcing bonding layer through on-line induction heating, and constructs a multi-level interface reinforcing system. Embedding a grid-shaped conductive layer in the integrated electric fusion welding pipe fitting, coating an interface matching layer, and realizing equal-strength connection of the joint and the pipe body by combining a grading electric fusion welding process. The invention solves the problems of debonding of steel-plastic interface, low strength of welded joint and poor sealing adaptability, and is suitable for gathering and transportation of high sulfur-containing oil and gas fields and deep sea oil and gas exploitation.

Inventors

  • CHEN WEI
  • WANG MIN
  • CHENG XIAOJUN

Assignees

  • 江苏狼博管道制造有限公司

Dates

Publication Date
20260512
Application Date
20260415

Claims (10)

  1. 1. The utility model provides an interface enhancement mode rubber ring electric smelting steel skeleton polyethylene composite pipe which characterized in that, interface enhancement mode rubber ring electric smelting steel skeleton polyethylene composite pipe contains: the composite pipe substrate pipe comprises an inner layer high-density polyethylene layer, an interface reinforced bonding layer, a steel skeleton reinforced layer and an outer protective layer high-density polyethylene layer from inside to outside in sequence; Wherein, the outer surface of the inner layer high-density polyethylene layer is introduced with carboxyl and amino polar functional groups after on-line plasma activation treatment by a plasma jet treatment device; The interface enhanced bonding layer is a blend of maleic anhydride grafted polyethylene and ethylene-acrylic acid copolymer, the interface enhanced bonding layer is coated on the outer surface of the inner layer high-density polyethylene layer, and maleic anhydride groups in the interface enhanced bonding layer and amino groups on the outer surface of the inner layer high-density polyethylene layer are subjected to chemical reaction to form amide bonds; The steel skeleton reinforcing layer is formed by winding a copper-plated steel wire with a nano silicon dioxide modified epoxy resin coated on the surface, and the nano silicon dioxide modified epoxy resin coating on the surface of the copper-plated steel wire is in physical interlocking and chemical reaction with the interface reinforcing bonding layer in the winding process; And the outer protective layer high-density polyethylene layer is coated on the outer surface of the steel skeleton reinforcing layer.
  2. 2. The preparation method of the interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe is characterized by comprising the following steps of: step 1, preparing a composite pipe substrate pipe, which specifically comprises the following substeps: The method comprises the steps of 1.1, extrusion molding and surface activation treatment of an inner layer high-density polyethylene layer, namely, mixing high-density polyethylene resin with carbon black master batches, an antioxidant and an ultraviolet absorber to form an inner layer mixture, extruding the inner layer mixture into an inner layer high-density polyethylene pipe blank through a first single screw extruder, and carrying out online plasma activation treatment on the outer surface of the inner layer high-density polyethylene pipe blank by adopting a plasma jet treatment device after the inner layer high-density polyethylene pipe blank is extruded from a machine head die orifice and the surface temperature is kept in a molten state interval; In 0.5 seconds after the plasma activation treatment of the step 1.1, sizing the activated inner layer high-density polyethylene pipe blank by a vacuum sizing sleeve, and uniformly coating the outer surface of the inner layer high-density polyethylene pipe blank with an interface reinforced adhesive layer material formed by blending maleic anhydride grafted polyethylene and ethylene-acrylic acid copolymer by a second single screw extruder by a coextrusion die; Step 1.3, winding forming and interface synchronous solidification of a steel skeleton reinforcing layer, namely, immediately after the interface reinforcing bonding layer is extruded and covered on the outer surface of the inner layer high-density polyethylene pipe blank in step 1.2, cross winding a copper-plated steel wire with the surface coated with nano silicon dioxide modified epoxy resin by a winding machine to form a steel skeleton reinforcing layer with a double-layer symmetrical structure, and in the winding process, on-line heating the copper-plated steel wire which is being wound by an intermediate frequency induction heating device to soften and partially solidify the nano silicon dioxide modified epoxy resin coating on the surface of the copper-plated steel wire, and performing physical interlocking and chemical reaction with the interface reinforcing bonding layer in a molten state; step 1.4, coating and shaping the outer-sheath high-density polyethylene, namely extruding the outer-sheath high-density polyethylene material out of the outer surface of the tube blank wound with the steel skeleton reinforcing layer through a third single screw extruder, and then cooling the whole composite tube to below 60 ℃ through a vacuum cooling shaping device to finish the preparation of the composite tube substrate tube; step 2, prefabricating an integrated electric melting welding pipe fitting, which specifically comprises the following substeps: injecting high-density polyethylene material into a mold by adopting an injection molding process to form an integrated electric welding pipe fitting blank with a bell and spigot at one end and a flat end at the other end, forming a plurality of spiral stress slow-release grooves in the inner wall of the bell and spigot of the pipe fitting in the mold design, and accurately positioning and embedding a prefabricated latticed conducting layer on the surface layer of the inner wall of the bell and spigot of the pipe fitting through a positioning needle in the mold in the injection molding process; Step 2.2, preparing an interface matching layer of a pipe fitting welding area and a pipe body, namely coating a layer of interface matching layer slurry on the inner wall surface of a pipe fitting faucet through a screen printing process, and drying after coating is finished; Step 2.3, installing and activating the embedded rubber ring, namely installing a fluorosilicone rubber ring in an annular groove on the inner wall of the pipe fitting bell and spigot, and soaking the fluorosilicone rubber ring in an ethanol solution containing a silane coupling agent for surface activation treatment before installing; Step 3, constructing an electric fusion welding and sealing system of the composite pipe and the pipe fitting, which specifically comprises the following substeps: removing the outer-layer high-density polyethylene layer at the end part of the composite pipe matrix pipe prepared in the step 1, exposing the steel skeleton reinforcing layer and the inner-layer high-density polyethylene layer, polishing the exposed end part of the steel skeleton reinforcing layer to be smooth, cleaning the outer surface of the composite pipe in the end part area, cleaning the inner wall of a bell and spigot of the integrated electric welding pipe prepared in the step 2, and inserting the pretreated end of the composite pipe matrix pipe into the bell and spigot of the integrated electric welding pipe; step 3.2, implementing a hierarchical electric welding process, namely connecting an output electrode of an electric welding machine to a binding post outside the integrated electric welding pipe fitting, starting a welding program, and welding by adopting a hierarchical welding process, wherein the hierarchical welding process sequentially comprises a preheating stage, a fusion welding stage and a pressure maintaining cooling stage; And 3.3, activating stress of a rubber ring sealing system, namely applying axial pressure maintaining pressure to the integrated electric welding pipe fitting and the composite pipe base pipe fitting through a hydraulic clamp in the pressure maintaining cooling stage after the electric welding in the step 3.2 is completed, so that the end part of the composite pipe base pipe fitting applies continuous axial extrusion force to the fluorosilicone rubber ring pre-embedded in the annular groove of the integrated electric welding pipe fitting, and the fluorosilicone rubber ring is elastically deformed and is tightly attached to the spiral stress slow release grooves on the outer wall of the integrated electric welding pipe fitting and the inner wall of the integrated electric welding pipe fitting.
  3. 3. The method for preparing the interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe according to claim 2, wherein in the step 1.1, the working gas of the plasma jet treatment device is a mixed gas of nitrogen and acrylic acid, the volume percentage of the acrylic acid in the mixed gas is 8%, the output power of the plasma jet treatment device is 450 watts, the treatment distance is 15 millimeters, and the treatment time is 2 seconds; The mass ratio of the maleic anhydride grafted polyethylene to the ethylene-acrylic acid copolymer in the interface enhanced bonding layer material in the step 1.2 is 65:35, and the extrusion thickness of the interface enhanced bonding layer is controlled between 0.3 mm and 0.5 mm; The diameter of the copper-plated steel wire in the step 1.3 is 0.8 millimeter, the nano silicon dioxide modified epoxy resin coating on the surface of the copper-plated steel wire is formed by mixing bisphenol A type epoxy resin, methyl hexahydrophthalic anhydride curing agent and silicon dioxide particles with the particle size of 30 nanometers according to the mass ratio of 100:80:5, the thickness of the nano silicon dioxide modified epoxy resin coating is 30 micrometers, the winding angle of the copper-plated steel wire is 58 ℃, and the temperature of the medium-frequency induction heating device for on-line heating of the copper-plated steel wire being wound is controlled between 140 ℃ and 150 ℃; the outer sheath high density polyethylene material in step 1.4 is the same as the inner layer mixture composition of the inner layer high density polyethylene layer in step 1.1.
  4. 4. The preparation method of the interface enhancement type rubber ring electric melting steel skeleton polyethylene composite pipe according to claim 2 is characterized in that in the step 2.1, the section shape of the spiral stress slow release groove is semicircular, the radius is 0.5 millimeter, the groove depth is 0.4 millimeter, the pitch of two adjacent spiral stress slow release grooves is 2 millimeters, the grid-shaped conductive layer is woven by tinned copper wires with the diameter of 0.3 millimeter, the mesh number of the grid-shaped conductive layer is 20 meshes, the resistance value of the grid-shaped conductive layer under the condition of 20 ℃ is 0.02 ohm/square centimeter, and the distance between the grid-shaped conductive layer and the inner wall surface of the pipe bell and spigot is 0.2 millimeter after the grid-shaped conductive layer is embedded in the inner wall surface of the pipe bell and spigot; The interface matching layer slurry in the step 2.2 consists of maleic anhydride grafted polyethylene, conductive carbon black and a coupling agent according to a mass ratio of 100:15:3, wherein the coupling agent is gamma-aminopropyl triethoxysilane, the coating thickness of the interface matching layer slurry is 0.1mm, and the drying treatment is that the interface matching layer slurry is dried for 30 minutes at the temperature of 80 ℃; The section of the fluorosilicone rubber ring in the step 2.3 is in an X shape, the Shore A hardness of the fluorosilicone rubber ring is 75 ℃, the compression set is less than 15% under the condition of 150 ℃ multiplied by 70 hours, the surface activation treatment is that the fluorosilicone rubber ring is soaked in an ethanol solution containing 1.5% of silane coupling agent by mass and is subjected to ultrasonic treatment for 30 minutes at 40 ℃, wherein the silane coupling agent is gamma-glycidoxypropyl trimethoxysilane.
  5. 5. The method for preparing the interface enhancement type rubber ring electric melting steel skeleton polyethylene composite pipe according to claim 2, wherein in step 3.1, the length of the outer sheath high density polyethylene layer is removed from the end of the composite pipe base pipe, and after the pretreatment end of the composite pipe base pipe is inserted into the bell and spigot of the integral electric melting welding pipe, a fit clearance between the outer wall of the composite pipe base pipe and the inner wall of the integral electric melting welding pipe is 0.2-0.3 mm; The preheating stage of the step 3.2 is to linearly raise the welding voltage to 32V within 30 seconds and keep the welding voltage for 20 seconds, the fusion welding stage of the step is to linearly raise the welding voltage from 32V to 39.5V within 15 seconds and keep the welding voltage for 60 seconds, and the pressure maintaining and cooling stage of the step is to apply an axial pressure maintaining pressure of 0.2 megapascals to the integrated electric smelting welding pipe fitting and the composite pipe base pipe fitting through a hydraulic clamp while the welding voltage is cut off and continuously cool for 300 seconds until the welding interface temperature is reduced to 80 ℃ or lower; And 3.3, the elastic deformation of the fluorosilicone rubber ring enables four lips of the fluorosilicone rubber ring to be closely attached to spiral stress slow-release grooves on the outer wall of the composite pipe base pipe and the inner wall of the integrated electric welding connecting pipe.
  6. 6. The method for preparing the interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe according to claim 2, which is characterized by further comprising the following substeps of: step 4.1, testing the axial tensile property and calibrating the feedback of the welded joint, namely, intercepting a sample containing the complete welded joint from a welded composite pipe system, mounting the sample on a universal testing machine for axial tensile test, and recording the maximum tensile load of the welded joint And a breaking position, said test results Axial tensile load with composite pipe substrate tubing Comparing if the following Lower than the said 95% Of the welding voltage curve in the step 3.2 is adjusted according to the test result; Step 4.2, high-temperature high-pressure cyclic aging test and calibration of the sealing system, namely, installing the pipe section with the joint prepared in the step 3 in a high-temperature high-pressure cyclic test device, taking nitrogen containing 10% of H 2 S by mass as a test medium, wherein the test pressure is 1.2 times of the nominal pressure of the pipe, the test temperature is 85 ℃, performing pressure cyclic fatigue test, the cycle frequency is 6 times/min, 5000 times of cycles are performed altogether, monitoring the leakage rate of the sealing system in real time through a pressure sensor and a helium mass spectrometer leak detector in the test process, and if the leakage rate exceeds the nominal pressure of the pipe in the test period And (3) Pa cubic meters per second, adjusting the surface activation treatment time of the fluorosilicone rubber ring in the step (2.3) or the pretreatment precision of the end part of the composite pipe in the step (3.1) according to failure analysis results.
  7. 7. The method for preparing an interface enhancement type rubber ring electric melting steel skeleton polyethylene composite pipe according to claim 6, wherein the axial tensile test in step 4.1 is carried out at an ambient temperature of 23 ℃ plus or minus 2 ℃ and a loading rate of 5 mm/min; The specific method for adjusting the welding voltage curve in the step 3.2 according to the test result in the step 4.1 is that when the And said at least one of The holding voltage of the fusion welding stage in step 3.2 is increased by 0.5V when the ratio of the holding voltage is in the range of 85% to 95% And said at least one of When the ratio of (2) is lower than 85%, the holding voltage of the fusion welding stage in the step 3.2 is increased by 1.0V, and the dwell cooling time of the dwell cooling stage in the step 3.2 is prolonged by 60 seconds.
  8. 8. The method for preparing the interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe according to claim 2, wherein in the step 1.1, the inner layer mixture is formed by mixing high-density polyethylene resin with 1.2% of carbon black master batch, 0.5% of antioxidant and 0.3% of ultraviolet absorbent in percentage by mass through a high-speed mixer at the temperature of 85 ℃ for 10 minutes, wherein the antioxidant is tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, and the ultraviolet absorbent is 2- (2 ' -hydroxy-3 ' -tert-butyl-5 ' -methylphenyl) -5-chlorobenzotriazole; The temperature of the extruder of the first single-screw extruder in the step 1.1 is controlled to be 190-210 ℃, and the in-line plasma activation treatment is carried out when the surface temperature of the inner layer high-density polyethylene pipe blank is kept in a melting state interval of 185-195 ℃ within 3 seconds after the inner layer high-density polyethylene pipe blank is extruded from a machine head die orifice; The processing temperature of the second single screw extruder in step 1.2 is controlled between 210 ℃ and 230 ℃; the processing temperature of the third single screw extruder in step 1.4 was controlled between 190 ℃ and 210 ℃.
  9. 9. The method for preparing the interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe according to claim 2, wherein in the step 1.3, when the nano silicon dioxide modified epoxy resin coating is in a physical interlocking and chemical reaction with the interface enhanced bonding layer in a molten state in a softened and partially solidified state, nano silicon dioxide particles in the nano silicon dioxide modified epoxy resin coating are used as nucleating agents to induce the polyethylene crystal morphology in the interface enhanced bonding layer to change, so that a compact cross crystal layer is formed.
  10. 10. The application of the interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe is characterized in that the interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe prepared by the preparation method of any one of claims 2 to 9 is applied to a gathering pipeline system of a high sulfur-containing oil and gas field or a deep sea oil and gas exploitation vertical pipe system with a water depth of more than 1500 meters.

Description

Interface-enhanced rubber ring electric-melting steel skeleton polyethylene composite pipe and preparation method and application thereof Technical Field The invention relates to the technical field of pipelines, in particular to an interface enhanced rubber ring electric melting steel skeleton polyethylene composite pipe and a preparation method and application thereof. Background Under the extreme working conditions of exploitation and transportation of petroleum and natural gas, especially deep sea oil and gas field development, gathering transportation of the gas field containing hydrogen sulfide, energy transportation in alpine regions and the like, a pipeline system faces multiple severe challenges such as high pressure, strong corrosion, severe temperature change, geological settlement and the like. Although the traditional metal pipeline (such as a seamless steel pipe) has high strength, the traditional metal pipeline has poor corrosion resistance, and particularly when high sulfur-containing media are conveyed, problems of pitting corrosion and Stress Corrosion Cracking (SCC) are frequent, so that high corrosion inhibitor injection cost and frequent maintenance and replacement are caused, and the total life cycle cost is high. Meanwhile, the metal pipeline has large weight and poor flexibility, and is extremely difficult to install in complex terrains and deep sea environments. To cope with the above problems, steel-framed polyethylene composite pipes have been developed. The pipeline combines the high strength of steel and the corrosion resistance of polyethylene, and adopts a steel wire or steel plate net frame as a reinforcing layer, and is covered with high-density polyethylene (HDPE) to form a composite structure, so that the pipeline has excellent performance under a specific pressure level. However, the prior art exposes a series of core defects during long-term service, severely restricting its application in critical fields: First, interface failure is the core pain point. The core problem of the existing steel skeleton polyethylene composite pipe is that the combination of a steel-plastic interface is not firm. During the manufacturing process, the steel wire or strip is bonded to the polyethylene matrix by physical interlocking or simple hot melt bonding. When the pipeline is subjected to internal pressure, axial stretching or periodic thermal cycling, the elastic modulus and the thermal expansion coefficient of the two materials are greatly different, microcracks and stress concentration are easily generated at the interface, and the interface is debonded. Once the interface is debonded, the reinforcement layer cannot effectively bear the load, the overall structural integrity of the pipe is lost, and internal pressure bulge or axial necking failure occurs. Secondly, the electrofusion joint is the weakest link of the structure. In the prior art, the connection between pipes is usually welded by adopting electrofusion pipe fittings. However, the resistance wires of the conventional electrofusion tube are buried only in the pure polyethylene layer, and when welded, the molten zone is limited to polyethylene material. For the steel skeleton polyethylene composite pipe, the continuous connection of the reinforcing layer (steel skeleton) cannot be realized during welding. Therefore, the welded joint becomes a pure plastic region without reinforcement, and the pressure bearing capacity of the welded joint is only 60% -70% of that of the pipe body. The structural characteristic of the 'strong pipe joint is weak' ensures that the pressure-bearing bottleneck of the whole pipeline system is locked at the joint part, and has great potential safety hazard. Again, the rubber seal is not sufficiently adaptable under complex conditions. In order to meet the requirements of the pipeline system on flexible sealing and axial displacement compensation, a rubber ring sealing structure is introduced into part of products. However, most of the existing rubber rings are made of single rubber materials, and when the rubber materials are conveyed with high-temperature (such as above 60 ℃) oil gas medium or exposed to ultraviolet light and ozone for a long time, the rubber materials are easy to age, harden, permanently deform and even crack, so that the sealing is invalid. In addition, the sealing interface of the traditional rubber ring and the pipe body lacks an effective stress slow-release structure, and peristaltic leakage is easy to generate under pressure fluctuation. Finally, the preparation process is difficult to realize the integrated coordination of the structures. At present, the production of the steel skeleton polyethylene composite pipe mostly adopts an off-line process of winding a skeleton firstly and coating plastic later, or a step-by-step composite process of inner tube-skeleton-outer tube. The processes are difficult to realize effective regulation and control on chemical bonding of a steel