CN-121989484-A - Preparation process of flexible composite pipe based on embedded sensing optical fiber

CN121989484ACN 121989484 ACN121989484 ACN 121989484ACN-121989484-A

Abstract

The invention discloses a preparation process of a flexible composite tube based on an embedded sensing optical fiber. The preparation process comprises the steps of firstly adopting a single-screw extruder to melt and extrude a special raw material of the HDPE pipe and color master batch to form a pipeline lining layer, secondly, pre-laying a continuous distributed sensing optical fiber on the outer surface of the cured lining layer according to a designed path, positioning the sensing optical fiber through a temporary fixed point and keeping winding traction allowance, then synchronously winding the reinforcing layer and the sensing optical fiber to enable the sensing optical fiber to be integrally embedded into the reinforcing layer, then co-extruding and coating the HDPE outer protective layer through the single-screw extruder, installing an end face integrated sealing joint and leading out a lead, finally, cutting the pipe body to a fixed length, flattening the end face, and coiling and packaging a final product according to standards. According to the invention, the monitoring function and the pipeline pressure-bearing structure are integrally designed, so that the real-time, online and nondestructive monitoring of the full life cycle health state of the flexible composite pipe is realized.

Inventors

LI QING
REN HONGWEI
ZHANG WEIJUN
LI XIAO
LI RUIYING
WANG YAPENG
ZHANG CHI

Assignees

北玻院(滕州)复合材料有限公司

Dates

Publication Date: 20260508
Application Date: 20260123

Claims (10)

1. The preparation process of the flexible composite tube based on the embedded sensing optical fiber is characterized by comprising the following steps of: (1) The extrusion process of the lining layer comprises the steps of adopting a single screw extruder to melt and extrude the special raw material of the HDPE pipe and the masterbatch to form the lining layer of the flexible composite pipe; (2) Pre-laying and initially positioning sensing optical fibers, namely pre-laying continuous distributed sensing optical fibers on the outer surface of the cured lining layer according to a designed path, and positioning the sensing optical fibers through temporary fixing points to ensure that the designed path is accurate and winding traction allowance is reserved; the design path is in an axial direction or a low-angle spiral shape, wherein the winding angle of the low-angle spiral shape is obviously smaller than that of a conventional reinforcing material, and the specific range is between 5 and 30 degrees; the temporary fixed point positioning selects high-temperature-resistant spot welding adhesive or removable adhesive tape for positioning; The winding traction allowance refers to the length of the sensing optical fiber exceeding the starting point and the finishing point of the theoretical winding path of the reinforcing layer in the winding process, and the length of the winding traction allowance is positively related to the outer diameter D of the flexible composite pipe body and the designed winding angle alpha; (3) Winding the reinforced layer and synchronously pulling the sensing optical fiber, namely winding and forming the reinforced material belt by adopting a multi-axis numerical control winding machine, adding a sensing optical fiber synchronous yarn feeding system on the multi-axis numerical control winding machine, arranging a special follow-up clamp, controlling the special follow-up clamp to pull the pre-laid sensing optical fiber in the step (2) through the sensing optical fiber synchronous yarn feeding system, keeping synchronous and same-path winding with the reinforced material, and finally enabling the sensing optical fiber to be integrally embedded into the reinforced layer; the winding tension of the sensing optical fiber is smaller than that of the reinforcing material; (4) The outer coating layer is subjected to coextrusion coating, namely an HDPE outer protective layer is subjected to coextrusion coating outside the tube blank which is wound by the reinforced layer and the sensing optical fiber through a second single screw extruder; (5) Installing an integrated sealing joint at the end part of the pipe body obtained in the step (4), wherein the joint adopts a stainless steel end flange with a central medium flow passage and a side wall bypass sealing cabin, and the sensing optical fiber lead penetrates into the side wall bypass sealing cabin; (6) Performing post-treatment, namely cutting the pipe body obtained in the step (5) to a fixed length, flattening the end surface, and performing pressure maintaining air tightness test on the sealing joint, and performing light transmission test on the guided sensing optical fiber to ensure that all grating signals are normal and the center wavelength drift is less than 1pm; (7) Coiling and packaging the final product obtained in the step (6) according to the standard.
2. The preparation process according to claim 1, wherein the key process parameters of the single screw extruder in the step (1) are controlled to be 180-220 ℃ of barrel temperature of the single screw extruder, 190-210 ℃ of die head temperature and 15-25 ℃ of cooling water temperature.
3. The process of claim 1, wherein the sensing fiber of step (2) is a polyimide coated fiber; the grating spacing is 0.5-5 m when the sensing optical fibers are distributed.
4. The process of claim 1, wherein the length L of the winding margin in the step (2) is equal to or greater than k pi D/sin α, D is the outer diameter of the flexible composite tube body, α is a designed winding angle, k is an empirical factor, and the value range is generally 1.5-3.
5. The preparation process according to claim 1, wherein the ratio of the winding tension Ts of the sensing optical fiber to the winding tension Tr of the reinforcing material in the step (3) is 1% or less and 10% or less, preferably 2% or less and Ts/Tr 5% or less; The reinforcing material belt is a glass fiber belt or a carbon fiber belt, namely the reinforcing material is glass fiber or carbon fiber; the key technological parameters of the multi-axis numerical control winding machine comprise that the winding angle of the reinforcing material belt is +/-55 degrees, and the ambient temperature is kept at room temperature.
6. The process of claim 1, wherein UV resistant master batch is added to the HDPE outer protective layer of step (4).
7. The preparation process according to claim 1, wherein in the step (4), the process parameters of the second single screw extruder are controlled to be 185-215 ℃ and the head pressure is controlled to be in the range of 15-35 MPa.
8. The process of claim 1, wherein the stainless steel end flange of step (5) is secured to the end of the pipe body by a dowel pin.
9. The manufacturing process according to claim 1, wherein in the step (5), at the communication part between the sensing optical fiber and the side wall bypass sealed cabin, the sensing optical fiber is cured by injecting a low-modulus flexible epoxy sealant by using an injector or fixed by adopting a sealing plug, and an inner sealing and stress buffer layer is formed after the sealant is cured.
10. A flexible composite pipe produced by the process of claims 1 to 9.

Description

Preparation process of flexible composite pipe based on embedded sensing optical fiber Technical Field The invention belongs to the technical field of flexible composite pipes, and particularly relates to a preparation process of a flexible composite pipe based on an embedded sensing optical fiber. Background The flexible composite pipe is used as a novel composite pipe and is widely applied to the fields of oil gas transportation and the like. Conventional flexible composite pipes (e.g., RTP pipes) are difficult to detect from the outside during service (especially in severe environments such as oil and gas transportation, deep sea applications, chemical industry, etc.), and serious safety accidents and economic losses can be caused by sudden failures. Therefore, it is necessary to detect it periodically to prevent accidents. Aiming at the flexible composite pipe, the existing detection means are mostly regular inspection or post analysis, early warning cannot be realized, and the maintenance cost is high and passive. Based on the intelligent technology iteration of the flexible composite pipe, which is being greatly pushed in the industry, an intelligent pipeline system with functions of strain real-time monitoring, accurate leakage positioning and risk autonomous early warning is constructed by integrating various sensors in the pipeline. The optical fiber microtube is pre-buried in the wall structure of the flexible composite pipe in the prior patent ZL201520095997.3, and although the real-time monitoring can be realized, the wall thickness of the inner liner of the flexible composite pipe is greatly increased and the local stress concentration is caused, thereby influencing the service life of the pipe. The traditional flexible composite pipe monitoring technology is mainly used for monitoring in a mode of sticking a sensor on the outer wall of a pipeline, but the sensor is easy to fail due to mechanical damage and corrosion, and the real state of a key enhancement layer in the pipeline cannot be accurately reflected. At present, the scheme of integrally designing the monitoring function and the pipeline pressure-bearing structure is not mature. The main technical difficulties faced include how the sensor survives the harsh extrusion winding process, interface bonding and signal interference problems of the sensing unit and the composite material, and how to achieve long-term stable signal transmission. Disclosure of Invention Aiming at the problems in the background technology, the invention provides a preparation process of a flexible composite tube based on an embedded sensing optical fiber, according to the invention, the monitoring function and the pipeline pressure-bearing structure are integrally designed, so that the real-time, online and nondestructive monitoring of the full life cycle health state of the flexible composite pipe is realized. In order to achieve the above object, the present invention provides the following technical solutions: a preparation process of a flexible composite tube based on an embedded sensing optical fiber comprises the following steps: (1) The extrusion process of the lining layer comprises the steps of adopting a single screw extruder to melt and extrude the special raw material of the HDPE pipe and the masterbatch to form the lining layer of the flexible composite pipe; The key technological parameters are controlled to be that the temperature of a machine barrel of a single screw extruder is 180-220 ℃, the temperature of a die head is 190-210 ℃, the temperature of cooling water is 15-25 ℃, and the inner wall of an inner liner is ensured to meet the quality requirements of smoothness and no defect; (2) Pre-laying and initially positioning sensing optical fibers, namely pre-laying continuous distributed sensing optical fibers on the outer surface of the cured inner liner according to a designed path, positioning the sensing optical fibers through temporary fixing points, ensuring that the designed path is accurate and winding traction allowance is reserved, wherein the step is to finish the spatial path pre-setting of sensing optical fiber elements, but the final coating is not formed; The design path is in an axial direction or a low-angle spiral shape, wherein the low-angle spiral shape generally refers to a winding angle which is significantly smaller than that of a conventional reinforcing material (such as a gold winding angle of 55 degrees), the specific range is generally between 5 degrees and 30 degrees, and the core aims to realize high axial sensitivity and good structural following performance of the sensing path; The sensing optical fiber is a polyimide coating optical fiber; the temporary fixed point positioning selects high-temperature-resistant spot welding adhesive or removable adhesive tape for positioning; The length of the winding traction allowance is positively related to the outer diameter (D) of the flexible composite pipe body and a desig