Production process of large-diameter flexible composite pipe

Abstract

The invention discloses a production process of a large-diameter flexible composite pipe, which comprises the following steps of: manufacturing a composite pipe lining layer material into a prefabricated sheet with a positioning mark and a temperature sensing grid, and processing the edge of the sheet into a beveled rabbet structure; under the protection of inert gas, the prefabricated sheet is rolled to be tubular through pulse laser welding, and longitudinal welding is completed; a pre-impregnated reinforced fiber belt is laid on the outer surface of the lining pipe, and interlayer compounding is achieved through isostatic pressing rolling after plasma surface treatment; gradient curing is carried out through segmented electromagnetic induction heating, and deformation is controlled in cooperation with a self-adaptive supporting system; and forming a functional coating outside the enhancement layer through an in-situ polymerization technology, and carrying out UV-LED curing and plasma hole sealing treatment. Through cooperative use of a low-temperature welding process and an inert gas protection system, the material heat influence in the welding process is effectively controlled, the performance degradation of a high polymer material is avoided, and the problem that the mechanical property of a welding seam area is reduced due to a traditional welding method is solved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer composite material pipeline manufacturing, in particular to a production process of large-diameter flexible composite pipes. Background Art

[0002] As a key component of modern chemical transportation systems, large-diameter flexible composite pipes have irreplaceable advantages in deep-sea oil and gas exploration, acid and alkali medium transportation, and other fields. Such pipes need to meet the following requirements at the same time:

[0003] 1. Large diameter forming requirements above DN800;

[0004] 2. Withstand working pressure above 6MPa;

[0005] 3. Adapt to operating temperature fluctuations from -40℃ to 120℃.

[0006] Currently, the industry's mainstream production process utilizes a multi-layer co-extrusion process. PVDF-based composite materials, due to their excellent corrosion resistance and mechanical strength, have become the preferred material for chemical pipelines. The international standard ISO 14692-3:2017 sets clear requirements for such pipes, including ovality and interlayer bond strength.

[0007] The hot-melt welding process in the existing technology will cause the PVDF molecular chain to undergo an irreversible transformation from the β-crystal form to the α-crystal form when the welding melting point is ≥90% Tm, causing the impact toughness of the weld area to decrease by 38%-42%. This defect directly affects the fatigue life of the pipeline under pressure pulsation conditions and becomes a key bottleneck restricting the improvement of pipeline service performance. Summary of the Invention

[0008] The object of the present invention is to provide a production process for large-diameter flexible composite pipes to solve the problems raised in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A production process for a large-diameter flexible composite pipe comprises the following steps:

[0011] Step S1: prefabrication of the composite pipe lining material into prefabricated sheets with positioning marks and temperature sensing grids, and processing the edges of the sheets into a mitered tenon structure;

[0012] Step S2, low-temperature tube forming, under the protection of inert gas, the prefabricated sheet is rolled into a tube by pulsed laser welding and the longitudinal weld is completed, and the welding temperature is controlled below the melting point of the material;

[0013] Step S3: in-situ reinforcement and composite, laying pre-impregnated reinforcement fiber tape on the outer surface of the liner pipe, and then performing isostatic rolling after plasma surface treatment to achieve interlayer composite;

[0014] Step S4: Curing and shaping, performing gradient curing by segmented electromagnetic induction heating, and controlling deformation with an adaptive support system;

[0015] In step S5, the functional layer is integrally formed, and a functional coating is formed outside the reinforcement layer by in-situ polymerization technology, and then subjected to UV-LED curing and plasma sealing treatment.

[0016] In the present invention, in step S1, the mortise and tenon joint structure is a mortise and tenon structure with an inclined plane angle of 45°±5°, and the assembly gap between adjacent sheets is 0.1-0.3 mm.

[0017] In the present invention, in step S2, the solid-state welding is laser welding, the welding heat input is controlled at 5 to 15 J / mm, and the peak temperature of the welding zone is 20 to 50° C. lower than the melting point of the material.

[0018] In the present invention, in step S3, the process parameters of the plasma treatment include: power density 0.5-1.5W / cm 2 The processing time is 10 to 30 seconds, and the working gas is a mixture of argon and oxygen with a mixing volume ratio of 4:1 to 9:1.

[0019] In the present invention, in step S4, the gradient solidification includes:

[0020] Divide the tube body into at least three temperature zones along the axial direction;

[0021] Each temperature zone is independently controlled, and the temperature difference between adjacent temperature zones is 10 to 30°C;

[0022] The curing temperature control accuracy is ±1°C.

[0023] In the present invention, in step S5, the formation of the functional coating includes:

[0024] forming a polymer layer with a thickness of 0.5 to 2 mm by chemical vapor deposition;

[0025] The UV light with a wavelength of 365-405 nm is used for curing, and the irradiation dose is 300-500 mJ / cm 2 .

[0026] A large-diameter flexible composite pipe is prepared by the method, and has a pipe diameter of 800 mm or greater, an ellipticity of 0.5% or less, and an interlayer peeling strength of 35 MPa or greater.

[0027] An apparatus for implementing the method, comprising:

[0028] a sheet material conveying device having a tenon alignment mechanism;

[0029] Laser welding device equipped with temperature feedback system;

[0030] A plasma processing apparatus comprising a gas mixing unit;

[0031] Multi-temperature zone curing furnace, each temperature zone is equipped with an independent electromagnetic induction coil.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention effectively controls the thermal impact of materials during the welding process by using a low-temperature welding process in conjunction with an inert gas protection system, avoids the degradation of polymer material properties, and solves the problem of decreased mechanical properties in the weld area caused by traditional welding methods.

[0034] 2. The present invention realizes precise temperature control and deformation adjustment during the pipe forming process through the synergistic effect of the multi-temperature zone gradient curing process and the adaptive support system, solves the problem of geometric deformation of large-diameter pipes during the curing process, and ensures the dimensional accuracy of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a main process flow chart of a production process for a large-diameter flexible composite pipe according to the present invention;

[0036] Figure 2 This is a piece-by-piece prefabrication sub-process of a production process for a large-diameter flexible composite pipe according to the present invention;

[0037] Figure 3 This is an equipment configuration diagram of a production process for a large-diameter flexible composite pipe according to the present invention;

[0038] Figure 4 This is a technical principle diagram of the production process of a large-diameter flexible composite pipe according to the present invention. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] like Figure 1-4 As shown, a production process for a large-diameter flexible composite pipe includes the following steps:

[0041] Step S1, slice prefabrication:

[0042] Using polyvinylidene fluoride (PVDF)-based nanocomposite materials, a prefabricated sheet with a width of 1 / 6 of the tube circumference was prepared by micro-extrusion. The edge of the sheet was processed into a tongue-and-groove structure with a bevel angle β = 43°, satisfying the following geometric relationship:

[0043]

[0044] Where t = 2.5mm sheet thickness, h = 3.66mm is the mortise depth. The positioning mark is laser etched to form a QR code array with a spacing of Δ x =150mm. The temperature sensing grid is printed with negative temperature coefficient thermistor material, and the resistance-temperature relationship satisfies:

[0045]

[0046] Wherein B=3950K±1%,R0=10kΩwhen T0=298K.

[0047] In the above step S1, the slicing prefabrication process further includes:

[0048] Step S101, pretreatment of raw materials, drying PVDF particles in an oven at 80°C for 4 hours until the moisture content is less than 0.02%, and adding nano-silica modifier (3.5 wt%) and antioxidant (0.5 wt%) in proportion.

[0049] Step S102, sheet extrusion, using a Φ120mm twin-screw extruder, set five temperature sections: 180 / 195 / 205 / 210 / 200℃, the die head temperature is controlled at 198±2℃, and the sheet is shaped by a three-roll calender with an upper roller of 90℃, a middle roller of 100℃, and a lower roller of 80℃.

[0050] Step S103, tenon processing, is performed using a diamond tool in a CNC machining center with a spindle speed of 8000 rpm and a feed rate of 600 mm / min. The tool is replaced after every 50 pieces are processed.

[0051] Step S104 , marking, uses a 20W fiber laser marking machine with marking parameters of 50kHz frequency, 0.05mm filling spacing, and 0.1±0.02mm marking depth.

[0052] Step S2, low temperature tube coiling:

[0053] In an argon protective atmosphere (oxygen content <50ppm), pulsed laser welding with a wavelength of 1064nm is used. The heat input Q is adjusted according to the welding speed v = 12mm / s:

[0054]

[0055] Peak temperature T pReal-time monitoring by infrared thermometer to meet:

[0056] T m -ΔT <T p <T m

[0057] Where T m =178℃ is the melting point of the material, ΔT=35℃. Weld strength σ w and parent material strength σ b The ratio reaches 0.92:

[0058]

[0059] In the above step S2, the low-temperature coiled tube forming process further includes:

[0060] Step S201, coiling preparation, pre-evacuate to -0.08 MPa in the inert gas protection chamber, fill with argon gas to a slightly positive pressure (105 kPa), and maintain a gas flow rate of 12 L / min.

[0061] Step S202: precise positioning, using a CCD vision system to identify positioning marks, with a manipulator repeatability accuracy of ±0.03mm, and applying a 5N preload force when the mortise and tenon joints are connected.

[0062] Step S203: laser welding, using a 300W pulsed laser, a pulse width of 0.8ms, a frequency of 40Hz, a defocusing amount of +0.5mm, and real-time power adjustment to ensure a penetration depth of 1.2±0.1mm.

[0063] Step S3, in-situ enhanced composite:

[0064] The reinforced fiber tape (60 vol% carbon fiber / epoxy resin) was treated with plasma at a power density of W = 1.2 W / cm 2 When , the surface energy γ is increased in accordance with:

[0065]

[0066] is the material constant, t = 20s processing time. The isostatic roller pressure p = 0.8MPa, the relationship between the interlayer bonding strength τ and pressure is:

[0067] τ=τ0+αln(p / p0)

[0068] τ0=28MPa, α=4.2, p0=0.1MPa.

[0069] In the above step S3, the in-situ reinforced composite process further includes:

[0070] Step S301, surface treatment, the plasma spray gun is 50 mm away from the tube body, the spray gun moves at a speed of 8 mm / s, and the surface energy is tested before and after treatment (needs to be ≥72 mN / m).

[0071] Step S302 , fiber laying, using 12K carbon fiber / epoxy resin prepreg tape, the tension control system response time is less than 0.1s, and the ply overlap width is 10±1mm.

[0072] Step S303 , roller pressing and laminating, the hardness of the silicone roller is 70 Shore A, the length of the preheating zone is 2 m, the temperature gradient is 80→100° C., and the contact length of the nip zone is 150 mm.

[0073] Step S4, curing and shaping:

[0074] The pipe body is divided into 5 temperature zones, and the temperature gradient satisfies:

[0075] T n =T n-1 +ΔT

[0076] ΔT = 15°C, n = 1-5 zone temperatures are 80°C / 95°C / 110°C / 125°C / 140°C respectively. The adaptive support system calculates the support force F based on the pipe diameter D = 850mm:

[0077]

[0078] E = 3.2 GPa is the elastic modulus, v = 0.38 is the Poisson's ratio, L = 2000 mm is the support distance, and δ = 0.4% is the allowable deformation.

[0079] In the above step S4, the gradient solidification and shaping process further includes:

[0080] Step S401, temperature control, each temperature zone is equipped with 3 sets of thermocouples, wherein the PID parameters are proportional band 15%, integral time 2 minutes, and over-temperature alarm threshold +5°C.

[0081] Step S402, deformation control, arranging 16-point laser displacement sensors, sampling frequency 100 Hz, hydraulic support system response time 50 ms.

[0082] Step S5: integrated functional layer forming:

[0083] A functional coating is formed outside the reinforcement layer by in-situ polymerization technology, and then subjected to UV-LED curing and plasma sealing treatment.

[0084] In the above step S5, the functional layer integrated molding process further includes:

[0085] Step S501, coating deposition, precursor solution flow rate 50 ml / min, carrier gas (N2) pressure 0.15 MPa, reaction chamber temperature 120±2°C.

[0086] Step S502: UV curing, using 48 sets of LED arrays, irradiation uniformity test once every 4 hours, and rotation curing speed of 3 rpm.

[0087] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0088] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A production process for large-diameter flexible composite pipes, characterized in that: The following steps are involved: Step S1: prefabrication of the composite pipe lining material into prefabricated sheets with positioning marks and temperature sensing grids, and processing the edges of the sheets into a mitered tenon structure; Step S2, low-temperature tube forming, under the protection of inert gas, the prefabricated sheet is rolled into a tube by pulsed laser welding and the longitudinal weld is completed, and the welding temperature is controlled below the melting point of the material; Step S3: in-situ reinforcement and composite, laying pre-impregnated reinforcement fiber tape on the outer surface of the liner pipe, and then performing isostatic rolling after plasma surface treatment to achieve interlayer composite; Step S4: Curing and shaping, performing gradient curing by segmented electromagnetic induction heating, and controlling deformation with an adaptive support system; In step S5, the functional layer is integrally formed, and a functional coating is formed outside the reinforcement layer by in-situ polymerization technology, and then subjected to UV-LED curing and plasma sealing treatment.

2. The production process of a large-diameter flexible composite pipe according to claim 1, characterized in that: In step S1, the mortise and tenon joint structure is a mortise and tenon structure with an inclined plane angle of 45°±5°, and the assembly gap between adjacent sheets is 0.1-0.3 mm.

3. The production process of a large-diameter flexible composite pipe according to claim 1, characterized in that: In step S2, the solid-state welding is laser welding, the welding heat input is controlled at 5 to 15 J / mm, and the peak temperature of the welding zone is 20 to 50° C. lower than the melting point of the material.

4. The production process of a large-diameter flexible composite pipe according to claim 1, characterized in that: In step S3, the process parameters of the plasma treatment include: power density 0.5-1.5 W / cm 2 The processing time is 10 to 30 seconds, and the working gas is a mixture of argon and oxygen with a mixing volume ratio of 4:1 to 9:

1.

5. The production process of a large-diameter flexible composite pipe according to claim 1, characterized in that: In step S4, the gradient curing includes: Divide the tube body into at least three temperature zones along the axial direction; Each temperature zone is independently controlled, and the temperature difference between adjacent temperature zones is 10 to 30°C; The curing temperature control accuracy is ±1°C.

6. The production process of a large-diameter flexible composite pipe according to claim 1, characterized in that: In step S5, the formation of the functional coating includes: forming a polymer layer with a thickness of 0.5 to 2 mm by chemical vapor deposition; The UV light with a wavelength of 365-405 nm is used for curing, and the irradiation dose is 300-500 mJ / cm 2 .

7. A large-diameter flexible composite pipe, characterized in that: The tube is prepared by the method according to any one of claims 1 to 6, and has a tube diameter of ≥800 mm, an ellipticity of ≤0.5%, and an interlayer peeling strength of ≥35 MPa.

8. An apparatus for implementing the method according to any one of claims 1 to 6, characterized in that: include: a sheet material conveying device having a tenon alignment mechanism; Laser welding device equipped with temperature feedback system; A plasma processing apparatus comprising a gas mixing unit; Multi-temperature zone curing furnace, each temperature zone is equipped with an independent electromagnetic induction coil.

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