Method and device for detecting blind area of pipe end of inner layer of ultra-thin composite pipe

Abstract

A method and apparatus for flaw detection of ultra-thin inner layer composite tubes without pipe end blind zones includes the following steps: 1) Install several jet-coupled ultrasonic detection units circumferentially on a jet detection coupled water circulation cavity. The jet detection coupled water circulation cavity is a cylindrical structure, and the central angles between each detection unit are the same, and they are arranged at equal intervals along the axial direction of the cavity; each detection unit is an ultrasonic detection channel; 2) The composite tube passes through the jet detection coupled water circulation cavity, and the height of the cavity is adjusted so that the axis of the cavity and the composite tube coincides; 3) Start the water coupling circulation system, drive the composite tube to pass through each adjacent detection unit at a uniform speed, and the dynamic water jet coupled ultrasonic waves enter the composite tube body for imaging detection until the entire composite tube passes through the detection unit; 4) Record the position information of each point of the composite tube and the corresponding acoustic signal of the corresponding position point one by one, and store them; judge and identify the composite tubes that are deemed unqualified based on the detection results.

Description

Technical Field

[0001] This invention relates to non-destructive testing technology, and in particular to a method and apparatus for flaw detection of ultra-thin inner layer composite pipes without pipe end blind zones. Background Technology

[0002] Currently, many industries urgently need high-performance, low-cost pipes. Besides meeting conventional mechanical performance requirements, these pipes also need to possess properties such as high-temperature resistance, corrosion resistance, erosion resistance, and oxidation resistance. However, it is particularly difficult for a single material to simultaneously possess all these comprehensive properties. Even expensive high-alloy steels, such as martensitic stainless steel, duplex stainless steel, nickel-based alloys, or titanium alloys, have their own shortcomings. With the development of manufacturing technology, various bimetallic composite pipes have emerged to address this situation. Bimetallic composite pipes are composed of two different metal materials, using carbon steel or low-alloy steel pipes as the base pipe, with a corrosion-resistant alloy layer laminated to the inner and outer surfaces. They are manufactured through specific physical deformation or metallurgical bonding. Through special deformation and connection techniques, bimetallic composite pipes tightly combine the base material and the lining, maximizing the advantages of both metals, overcoming the performance defects of single-metal materials, and simultaneously reducing the overall cost of use.

[0003] Bimetallic composite pipes are a new type of steel pipe that combines a base steel pipe and a cladding metal using mechanical or metallurgical methods. The carbon steel base pipe primarily serves as a pressure-bearing and rigid support, while the cladding provides functional protection such as corrosion resistance, high-temperature oxidation resistance, and wear resistance. Bimetallic composite pipes retain the advantages of both the base pipe and the cladding metal while addressing their respective shortcomings. The base pipe's diameter, wall thickness, and steel grade can be adjusted according to structural and service requirements, while the cladding metal can be selected from different corrosion-resistant metals or alloys based on service conditions. Bimetallic composite pipes effectively reduce the cost of traditional high-alloy products, costing only 1 / 5 to 1 / 2 of pure corrosion-resistant alloy pipes. Comparative analysis of the comprehensive performance of various pipelines used for oil and gas transportation by domestic professional research institutions shows that bimetallic composite pipes rank among the best in terms of overall performance.

[0004] In my country, there are mature national standards that specify corresponding methods for the flaw detection of steel pipes. For example, GB / T 5777-2008 "Ultrasonic Testing Method for Seamless Steel Pipes" specifies the use of the refracted transverse wave flaw detection method. By incident ultrasonic waves at a certain angle to the surface of the steel pipe, the longitudinal waves are completely reflected, and the refracted transverse waves are used to enter the steel pipe for testing.

[0005] However, for new steel pipe products like bimetallic composite pipes, where the inner layer metal is expensive, the thickness of the inner layer metal will be designed and manufactured to a relatively low cost level that meets the application requirements, depending on the application scenario. Figure 1As shown, due to cost reduction efforts, the actual thickness of the functional layer used is extremely thin, less than 1 mm. This means that existing conventional online flaw detection equipment either cannot detect defects at the interface 30 between the functional layer 20 and the substrate layer 10 of the bimetallic composite pipe 100 because the defects are too small, or the signal is completely masked by the backwave signal. Consequently, existing flaw detection technology cannot identify manufacturing defects in composite steel pipes with such thin inner layers. Therefore, the quality inspection targets and dimensional equivalent requirements for flaw detection in composite pipes with extremely thin inner layers differ significantly from traditional flaw detection requirements. Previous quality inspection methods are no longer applicable, especially when the inner metal layer is extremely thin; traditional steel pipe flaw detection methods are no longer suitable for the quality inspection of bimetallic composite pipes.

[0006] Furthermore, due to limitations in the testing principles, existing steel pipe flaw detection standards and methods all suffer from the problem of undetectable ends of the steel pipe, resulting in a pipe-end blind zone. Among various steel pipe flaw detection equipment, only contact-type equipment that rotates the steel pipe in place / moves the probe axially has a relatively small pipe-end blind zone. Other flaw detection methods typically have blind zones of around 200mm, and some even exceed 300mm. This is because the coupling water chamber used in rotating probe methods has circular holes on both sides for the steel pipe to pass through. Using plugs adapted to different pipe diameters maintains good coupling within the water chamber during flaw detection. However, when the steel pipe end enters the chamber, the coupling water leaks out through the circular holes on both sides, making the pipe end undetectable.

[0007] Specialized steel pipe product standards require full-body flaw detection, allowing no blind spots. To address this, steel pipe flaw detection equipment manufacturers have developed dedicated pipe end flaw detection equipment. Automatic pipe end flaw detection equipment typically operates in either a partial water immersion or contact mode. The partial water immersion method involves rotating the steel pipe in place, with an overflow probe box carrying the probe moving along the underside of the pipe; this type of equipment is suitable for flaw detection of small to medium diameter steel pipes. The contact method involves rotating the steel pipe in place, with a water film coupling probe moving axially along the top of the pipe; this type of equipment is suitable for flaw detection of large diameter steel pipes.

[0008] Bimetallic composite pipes with extremely thin inner metal layers are a new type of steel pipe product that has emerged under the current progress of the manufacturing industry. The quality inspection targets and dimensional equivalent requirements are very different from traditional flaw detection requirements.

[0009] Currently, there is virtually no method for flaw detection in composite pipes with extremely thin inner layers. All types of non-destructive testing methods have limitations. The existing non-destructive testing methods are as follows:

[0010] 1. The composite pipe body is a bimetallic inner layer with an extremely thin inner layer. Defects such as pores and poor bonding exist in the inner layer area, making conventional ultrasonic testing methods no longer applicable.

[0011] 2. Both magnetic particle and eddy current methods are difficult to use for automatic flaw detection of the inner layer of steel pipes;

[0012] 3. X-ray methods also struggle to achieve the required sensitivity to address the current problems.

[0013] 4. Even using ultrasonic guided wave methods, it is difficult to achieve the required flaw detection sensitivity level for bimetallic composite pipes, let alone realize online automatic flaw detection;

[0014] Another example is the "composite pipe flaw detection device" disclosed in Chinese Patent Publication No. CN210639145U. This device is a flaw detection tool for steel pipe products produced by various conventional composite manufacturing processes. It does not involve the technical principle of online imaging detection involved in our patent application, nor does it involve the characteristics of the test object with an extremely thin inner layer of less than 1 mm in thickness, nor does it involve the problem of blind spots at both ends of the steel pipe in online flaw detection that this invention plans to solve.

[0015] The Chinese patent publication CN206497075U discloses "An ultrasonic flaw detection machine tool for composite pipes". This device is also a flaw detection tool for composite steel pipe products using the contact water film method, but it does not solve the problem of blind zones at both ends of the steel pipe during online flaw detection.

[0016] The Chinese patent publication CN208457441U discloses a "flaw detection device for stainless steel-lined composite pipes". This device is a stress detection tool that uses a tensile strain gauge connected to an ammeter via a bridge circuit. However, it does not solve the problem of blind spots at both ends of the pipe during online flaw detection.

[0017] Although there are currently more than a dozen mature non-destructive testing (NDT) methods and over a thousand types of NDT instruments and equipment, most of the available NDT methods for steel pipes have limitations in their testing principles. Therefore, to achieve composite pipe flaw detection technology without blind spots at the pipe ends, we cannot be limited to conventional ultrasonic testing methods for steel pipes, or various other testing methods such as eddy current, X-ray, infrared, microwave, and laser ultrasonic testing; new methods must be designed. Summary of the Invention

[0018] The purpose of this invention is to provide a method and apparatus for flaw detection of bimetallic composite pipes with extremely thin inner layers without pipe end blind zones. This method addresses the difficulty of pipe end blind zones in bimetallic composite pipes and enables online flaw detection of bimetallic composite pipes with extremely thin inner layers (<1mm) without pipe end blind zones at the lowest possible cost.

[0019] To achieve the above objectives, the technical solution of the present invention is as follows:

[0020] A flaw detection method for ultra-thin inner layer composite pipes without pipe end blind zones includes the following steps:

[0021] 1. Several jet-coupled ultrasonic detection units are installed circumferentially on a jet detection coupled water circulation cavity. The jet detection coupled water circulation cavity is a cylindrical structure. The central angles of each detection unit are the same, forming a fan-shaped distribution. They are arranged at equal intervals along the axial direction of the jet detection coupled water circulation cavity. The axial distance x between adjacent detection units is between 30 and 60 mm, and the radial distance y is between 5 and 10 mm, or the central angle between adjacent detection units is between 5° and 15°. Each detection unit is an ultrasonic detection channel. The concentric height of the detection units is adjustable.

[0022] 2. Insert the composite pipe into the jet detection coupling water circulation chamber, and adjust the height of the jet detection coupling water circulation chamber so that the axis of the chamber and the composite pipe are aligned.

[0023] 3. Start the water coupling circulation system to drive the composite tube to pass through each adjacent detection unit at a constant speed. Dynamic water jet coupled ultrasonic waves enter the composite tube body for imaging detection until the entire composite tube passes through the detection unit, and the detection ends.

[0024] 4. The position information of each point of the composite tube obtained by the detection unit is matched one by one with the corresponding acoustic signal at the position point and stored; the composite tubes that are deemed unqualified are identified and judged based on the detection results.

[0025] Preferably, the circumference of the composite pipe is divided into several sectors in the circumferential direction. For each sector, a series of jet-coupled ultrasonic testing units that meet the circumferential resolution requirements for flaw detection are arranged to carry out the detection. The flaw detection of the entire composite pipe, including the pipe end parts in all sectors, is completed by using the axial reciprocating working mode of the composite pipe.

[0026] This invention divides the composite pipe circumferentially into multiple sectors and reciprocates axially to detect individual sectors. Within each sector, a series of jet-coupled ultrasonic testing units are arranged to meet the circumferential resolution requirements for flaw detection. For composite pipes of different diameters, the distance between the series of jet-coupled ultrasonic testing units installed on the coupled cylindrical cavity and the steel pipe can be adjusted to achieve full detection within a certain pipe diameter range.

[0027] This invention eliminates the need for plugs used in conventional steel pipe flaw detection. It utilizes dynamic water jet coupling to maintain good coupling within the water cavity during the flaw detection process. After the water jet coupling ends, the water naturally falls into the circulating water system and is recycled back to the water tower tank for reuse. The purpose of this is twofold: first, flaw detection using ultrasonic waves requires water to couple the sound waves into the steel pipe; second, it employs a circulating water system in conjunction with a water tower-type static water coupling ultrasonic wave detection. The coupling water passes through jet heads arranged in a large cavity, with as many jet heads as channels. This overcomes the problem in conventional steel pipe flaw detection where, after the ends enter the cavity, the coupling water leaks out through the circular holes on both sides, preventing detection at both ends of the composite pipe. This invention efficiently achieves continuous quality detection at both ends of the composite pipe.

[0028] The pipe-end blind zone flaw detection method described in this invention employs a circulating water system in conjunction with a water tower-type static water-coupled ultrasonic wave detection. The ultrasonic sound field can use point focusing or line focusing. For example, when using point focusing, the central axis of the point focusing sound field intersects perpendicularly with the radial central axis of the composite pipe, thus incident the sound wave into the interior of the composite pipe. When using line focusing, the symmetrical central plane of the line focusing sound field passes through the radial central axis of the composite pipe, and the focal line remains parallel to it, thus incident the sound wave into the interior of the composite pipe. The bimetallic composite pipe under inspection is located at a reasonable intermediate position between the sound source and the focal point (line), which ensures that the ultrasonic energy can be concentrated in the extremely thin inner layer region of the bimetallic composite pipe, which is beneficial for defect detection.

[0029] This invention employs a jet-coupled water circulation chamber structure. This structure is assembled from multiple concentric, height-adjustable, series of jet-coupled ultrasonic detection units, ensuring that the composite steel pipe can freely pass through the entire detection unit, and that the coupling water can flow freely between each individual detection unit. After jet-water coupling, the coupled water naturally falls into the circulation water path and is recycled back to the water tower tank for reuse. The velocity of the water flow from the jet head can be determined based on the designed jet head structure, with the principle being that the ejected water stream is stable and columnar, free of air bubbles and with minimal turbulence.

[0030] The present invention describes a flaw detection method for ultra-thin bimetallic composite pipes without pipe end blind zones, which involves continuous mechanical scanning imaging detection from beginning to end for the unique defects of ultra-thin bimetallic composite pipes.

[0031] The flaw detection method for the inner layer of ultra-thin bimetallic composite pipes with no pipe end blind zone involves the following aspects:

[0032] A series of concentrically height-adjustable jet-coupled ultrasonic testing units are installed on the jet testing coupling water circulation cavity. Each unit is an ultrasonic detection channel. The ultrasonic waves are dynamically coupled into the composite pipe body through water jet to perform composite quality imaging detection. The ultrasonic waves with a certain frequency and a certain sound field distribution are controlled to act as a detection probe. The defect detection is achieved by acting on the extremely thin inner layer of the bimetallic composite pipe in a reasonable ultrasonic detection mode.

[0033] The detection units are arranged in a fan shape with the same angle in the circumferential projection, and are equally spaced in the axial direction.

[0034] The reason for the spacing between the detection units is that the jet head corresponding to each detection point in this invention has a certain size. If a circular shape is used, the diameter is between 30 and 60 mm. Therefore, the distance x between adjacent detection points is between 30 and 60 mm.

[0035] The apparatus for a tube-end-free flaw detection method for ultra-thin inner layer composite tubes according to the present invention comprises:

[0036] Base;

[0037] The detection chamber is located at the center of the top surface of the base, with inlet and outlet corresponding to the center of its two sides;

[0038] A jet detection coupled water circulation cavity is provided. The jet detection coupled water circulation cavity is a cylindrical structure that can be raised and lowered within the detection box. Its bottom has inlet and outlet water ports and corresponding inlet and outlet water pipes. Several jet-coupled ultrasonic detection units are installed circumferentially on the top surface of the jet detection coupled water circulation cavity. The central angles of each detection unit are the same, forming a fan-shaped distribution. These units are evenly spaced along the axial direction of the jet detection coupled water circulation cavity, and adjacent detection units maintain a certain axial and radial spacing. Each detection unit is an ultrasonic detection channel.

[0039] A coupling water circulation tank is installed inside the base and is connected to the inlet and outlet pipes of the jet detection coupling water circulation chamber through inlet and outlet water pipes;

[0040] Two clamping mechanisms are respectively disposed on the top surface of the base on both sides of the detection box. The clamping mechanisms include:

[0041] A pair of clamping rollers, arranged vertically, are positioned at the center of the top surface of the base at the inlet / outlet of the detection box.

[0042] The drive mechanism is located on the top surface of the base on one side of the detection box;

[0043] The gripper is connected to the drive mechanism and is driven by the drive mechanism to move left and right along the axial direction of the top surface of the base; the gripper and the gripping roller are located on the same axis.

[0044] Preferably, the jet detection coupling water circulation cavity is composed of several detection sub-cavities connected in series. Each detection sub-cavity is provided with a mounting hole for installing a jet coupling ultrasonic detection unit, and a jet coupling ultrasonic detection unit is installed thereon. The mounting holes on each detection sub-cavity are arranged at equal intervals along the axial direction of the jet detection coupling water circulation cavity, and the central angles between each jet coupling ultrasonic detection unit are the same, so that the jet coupling ultrasonic detection units form a fan-shaped distribution. Each jet coupling ultrasonic detection unit is an ultrasonic detection channel.

[0045] Preferably, the drive mechanism includes:

[0046] Two guide rails and their sliders are arranged in parallel on the top surface of the base;

[0047] The mounting plate has sliders connected to the two guide rails at both ends of its bottom surface, and a connecting block is provided in the center of the bottom surface of the mounting plate;

[0048] A ball screw, with its two ends arranged parallel to each other between two guide rails via bearing seats, and the screw nut on the ball screw connected to the connecting block;

[0049] A drive motor, the output shaft of which is connected to one end of the ball screw.

[0050] Preferably, the drive motor is a servo motor.

[0051] Preferably, the axial spacing x between adjacent detection units is between 30 and 60 mm, and the radial spacing y is between 5 and 10 mm, or the central angle between adjacent detection units is between 5° and 15°.

[0052] At the start of the testing process, the bimetallic composite tube product is fixed by a clamp after passing through the feed roller conveyor. The clamp then transports the bimetallic composite tube into the coupling cavity, where detection units are located in a ring-shaped spatial position that meets the detection conditions. The detection units are activated, and the clamp stably holds and drives the composite tube to pass through each adjacent detection unit at a uniform speed. A series of water jet detection units periodically emit ultrasonic waves into the interior of the composite tube according to set conditions. The testing begins when the composite tube enters the detection unit and ends when it exits. The control program automatically records the waveforms at each detection position, matching the position information of each point on the composite tube obtained by the detection unit with the corresponding acoustic signal, and stores the data. Finally, based on the test results, a judgment is made. For composite tube products deemed unqualified, an alarm is triggered, and a marking device is activated to mark the composite tubes to distinguish them from qualified products. The final test result report is then printed.

[0053] This invention, through the aforementioned detection device, enables composite pipes of different diameters (e.g., 50-200mm) to maintain alignment between the axis of the jet detection coupling water circulation cavity and the axis of the composite pipe when the composite pipes pass through the coupling cavity and enter the detection state. This can be achieved by adjusting the vertical height of the coupling cavity on the base. Furthermore, by adjusting the series of jet-coupled ultrasonic detection units installed on the jet detection coupling water circulation cavity, the ultrasonic sensors within each unit can be adjusted to optimal detection conditions at a concentric height, and each jet-coupled ultrasonic detection unit can perform flaw detection tasks under the same operating conditions.

[0054] The beneficial effects of this invention are:

[0055] The flaw detection method for ultra-thin inner layer composite tubes without blind zone at the tube ends described in this invention can solve the problem in conventional composite tube flaw detection where coupling water leaks out through the round holes on both sides of the cavity after the end enters the cavity, making it impossible to detect the tube ends at both ends of the composite tube. It can efficiently realize continuous quality detection at both ends of the composite tube, eliminating the technical barriers to non-destructive testing of quality between innovative composite tube products and their market application. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the cross-section of a bimetallic composite pipe;

[0057] Figure 2 This is a schematic diagram of the jet detection coupled water circulation cavity for flaw detection of bimetallic composite pipes according to the present invention;

[0058] Figure 3 This is a schematic diagram of the cross-sectional projection of the bimetallic composite pipe according to the present invention.

[0059] Figure 4 This is a schematic diagram of sector division for flaw detection of the bimetallic composite pipe described in this invention;

[0060] Figure 5 This is a schematic diagram of the structure of the bimetallic composite tube flaw detection device of the present invention;

[0061] Figure 6 This is a schematic diagram of the jet detection coupled water circulation cavity in the bimetallic composite pipe flaw detection device of the present invention;

[0062] Figure 7 This is a schematic diagram of jet detection entering the cavity from the left end of the composite pipe in the pipe-end-less blind zone flaw detection method described in this invention;

[0063] Figure 8 This is a schematic diagram of jet detection at the right end of the composite pipe leaving the cavity in the tube-free blind zone flaw detection method described in this invention. Detailed Implementation

[0064] See Figure 5 The apparatus for a tube-end blind zone flaw detection method for ultra-thin inner layer composite tubes according to the present invention comprises:

[0065] Base 4;

[0066] The detection box 2 is located at the center of the top surface of the base 4, with inlet and outlet corresponding to the center of its two sides;

[0067] A jet detection coupled water circulation cavity 3 is a cylindrical structure that can be raised and lowered within the detection box 2. Its bottom has inlet and outlet ports and corresponding inlet pipes 31 and 32. Several jet-coupled ultrasonic detection units 1 and 1' are installed circumferentially on the top surface of the jet detection coupled water circulation cavity 3. The central angles of each detection unit 1 and 1' are the same, forming a fan-shaped distribution. These units are evenly spaced along the axial direction of the jet detection coupled water circulation cavity, and adjacent detection units 1 and 1' maintain a certain axial and radial distance. Each detection unit is an ultrasonic detection channel.

[0068] The coupling water circulation tank 5 is installed inside the base 4 and is connected to the inlet and outlet water pipes of the jet detection coupling water circulation cavity 3 through inlet and outlet water pipes;

[0069] Two clamping mechanisms 6 and 6' are respectively disposed on the top surface of the base 4 on both sides of the detection box 2. The clamping mechanism 6 (taking clamping mechanism 6 as an example, the same below) includes:

[0070] A pair of clamping rollers 61 are arranged vertically and positioned at the center of the top surface of the base 4 at the inlet / outlet of the detection box 2;

[0071] The drive mechanism 62 is disposed on the top surface of the base 4 on one side of the detection box 1;

[0072] The clamp 63 is connected to the drive mechanism 62 and is driven by the drive mechanism 62 to move left and right along the axial direction of the top surface of the base 4; the clamp 63 and the clamping roller 61 are located on the same axis.

[0073] See Figure 6The jet detection coupled water circulation cavity 3 of the present invention is composed of several detection sub-cavities 301, 302, ... 30n connected in series. Each detection sub-cavity 301, 302 is provided with a mounting hole 3011, 3021, ... 30n1 for installing a jet coupled ultrasonic detection unit, and a jet coupled ultrasonic detection unit 1, 1' is installed thereon. The mounting holes on each detection sub-cavity are arranged at equal intervals along the axial direction of the jet detection coupled water circulation cavity, and the central angles between each jet coupled ultrasonic detection unit are the same, so that the jet coupled ultrasonic detection units form a fan-shaped distribution. Each jet coupled ultrasonic detection unit is an ultrasonic detection channel.

[0074] Preferably, the drive mechanism includes:

[0075] Two guide rails and their sliders are arranged in parallel on the top surface of the base;

[0076] The mounting plate has sliders connected to the two guide rails at both ends of its bottom surface, and a connecting block is provided in the center of the bottom surface of the mounting plate;

[0077] A ball screw, with its two ends arranged parallel to each other between two guide rails via bearing seats, and the screw nut on the ball screw connected to the connecting block;

[0078] A drive motor, the output shaft of which is connected to one end of the ball screw.

[0079] Preferably, the drive motor is a servo motor.

[0080] Preferably, the axial spacing x between adjacent detection units is between 30 and 60 mm, and the radial spacing y is between 5 and 10 mm, or the central angle between adjacent detection units is between 5° and 15°.

[0081] See Figures 2-8 The present invention provides a method for detecting defects in a composite tube with an extremely thin inner layer without blind spots at the tube ends, comprising the following steps:

[0082] 1) Several jet-coupled ultrasonic detection units 1, 1' are installed circumferentially on the jet detection coupling water circulation cavity. The jet detection coupling water circulation cavity is a cylindrical structure. The central angles of each jet-coupled ultrasonic detection unit 1, 1' are the same, forming a fan-shaped distribution. They are arranged at equal intervals along the axial direction of the jet detection coupling water circulation cavity. The axial distance x between adjacent jet-coupled ultrasonic detection units 1, 1' is between 30 and 60 mm, and the radial distance y is between 5 and 10 mm. Alternatively, the central angle between adjacent jet-coupled ultrasonic detection units 1, 1' is between 5° and 15°. Each jet-coupled ultrasonic detection unit 1, 1' is an ultrasonic detection channel. The concentric height of the detection units is adjustable.

[0083] 2) Pass the composite pipe 100 through the jet detection coupling water circulation cavity, and adjust the height of the jet detection coupling water circulation cavity so that the axis of the cavity and the composite pipe are aligned.

[0084] 3) Start the water coupling circulation system to drive the composite tube to pass through each adjacent detection unit at a constant speed. Dynamic water jet coupled ultrasonic waves enter the composite tube body for imaging detection until the entire composite tube passes through the detection unit, and the detection ends.

[0085] 4) The position information of each point of the composite tube obtained by the jet-coupled ultrasonic testing unit is matched one by one with the corresponding acoustic signal of the position point and stored; the composite tubes that are deemed unqualified are identified and judged based on the test results.

[0086] See Figure 4 The circumference of the composite pipe 100 is divided into several sectors 101 in the circumferential direction. For each sector, a series of jet-coupled ultrasonic testing units 1 and 1' that meet the circumferential resolution requirements of the flaw detection are arranged to carry out the detection. The flaw detection of the entire composite pipe, including the pipe end parts in all sectors, is completed in the axial reciprocating working mode of the composite pipe.

[0087] This invention divides the circumference of the composite pipe into multiple sectors (more sectors require more reciprocating detection, but lower equipment manufacturing costs). Within each sector, a series of jet-coupled ultrasonic testing units are arranged to meet the circumferential resolution requirements for flaw detection. Using an axial reciprocating working mode, the entire composite pipe, including the pipe ends within all sectors, is inspected for flaws. The sector division and the arrangement of adjacent jet-coupled ultrasonic testing units within each sector are as follows: Figure 4 As shown.

[0088] For composite pipes of different diameters, the distance between a series of jet-coupled ultrasonic testing units mounted on a cylindrical coupling cavity and the composite pipe can be adjusted to achieve full inspection within a certain pipe diameter range. This invention divides the circumference into multiple sectors, completing one sector of the composite pipe's circumference at a time.

[0089] See Figure 7 , Figure 8 , Figure 7 The image shows the jet detection process where the left end of the composite pipe 100 enters the detection sub-cavity 301 of the jet detection coupling water circulation cavity 3. Figure 8 The image shows the jet detection of the right end of the composite tube 100 leaving the 30nth detection sub-cavity.

[0090] When the composite pipe 100 enters the coupling water circulation cavity from the left end for flaw detection, and finally leaves the coupling water circulation cavity from the right end, both ends of the pipe can be subjected to the same flaw detection as the pipe body. It can be seen that, due to the use of jet coupling, when both ends of the composite pipe enter and leave the coupling water circulation cavity in one direction, jet flaw detection can be carried out as usual. The detection is not hindered by the fact that the side of the coupling water circulation cavity is not blocked after the pipe ends enter the coupling water circulation cavity.

[0091] Example

[0092] Taking the detection of a composite pipe with an outer diameter of 100mm as an example, the mechanical imaging grid spacing of the inner wall of the composite pipe to be detected must be no less than 1mm in order to avoid missing detection. If the pipe wall thickness is 10mm, the composite layer thickness is 1mm, the composite layer is located on a circle with a diameter of 80mm, and the inner diameter of the composite steel pipe is 78mm.

[0093] The detection of a composite tube is completed by repeating the process 8 times. Each detection is completed within a 45-degree sector around the circumference. By repeating the detection process to detect the 8 45-degree sectors around the circumference of the composite tube, the detection of a composite tube can be completed.

[0094] The diameter of the probed circle is 80mm, the circumference is approximately 251.2mm, the sector length corresponding to each 45-degree angle is 31.4mm, and the design uses 32 channels.

[0095] It uses 32 channels, which is also Figure 2 There are 32 detection points in the middle. In the circumference of the composite pipe, these 32 channels are evenly distributed in a sector with an angle of 45 degrees. Because the detection is carried out in the direction of the jet in each channel is perpendicular to the axis of the steel pipe, that is, the angle between the directions of two adjacent jet channels is about 1.4°.

[0096] The designed circular coupling water circulation cavity has a diameter of 500 mm and a circumference of 1.57 m. The corresponding length of the 45-degree sector around the composite pipe is 196.25 mm. For a 32-channel detection system, the projected distance between any two adjacent detection channels around the composite pipe is 6.13 mm. Figure 2 In the figure, y = 6.13 mm.

[0097] The jet head has a diameter of 40mm, and the axial projection distance between two adjacent detection channels on the composite tube is 40mm. Figure 2 In the figure, x=40mm, and the total length of the 32 channels is less than 1.28m. The angle between the detection line formed by all detection points and the axis of the composite tube is calculated as: arctg(6.13 / 40)=8.7°.

[0098] The above describes the process of detecting one composite tube by dividing the circumference of the composite tube into eight 45-degree sectors. If the manufacturing cost of the equipment is to be reduced, or if the detection time is sufficient, the number of channels can be halved to 16 channels. In this case, if the diameter of the circular coupled water circulation cavity is still 500 mm, its overall length will be less than 614 mm, and so on.

Claims

1. A flaw detection method for ultra-thin inner layer composite pipes without pipe end blind zones, characterized in that, Includes the following steps: 1) Several jet-coupled ultrasonic detection units are installed circumferentially on the jet detection coupling water circulation cavity. The jet detection coupling water circulation cavity is a cylindrical structure. The central angles of each detection unit are the same, forming a fan-shaped distribution. They are arranged at equal intervals along the axial direction of the jet detection coupling water circulation cavity. The axial distance x between adjacent detection units is between 30 and 60 mm, and the radial distance y is between 5 and 10 mm, or the central angle between adjacent detection units is between 5° and 15°. Each detection unit is an ultrasonic detection channel. The concentric height of the detection units is adjustable. 2) Connect the composite pipe to the jet detection coupling water circulation cavity, and adjust the height of the jet detection coupling water circulation cavity so that the axis of the cavity and the composite pipe are aligned. 3) Start the water coupling circulation system to drive the composite tube to pass through each adjacent detection unit at a constant speed. Dynamic water jet coupled ultrasonic waves enter the composite tube body for imaging detection until the entire composite tube passes through the detection unit, and the detection ends. 4) The position information of each point of the composite tube obtained by the detection unit is matched one by one with the corresponding acoustic signal of the position point and stored; the composite tubes that are deemed unqualified are identified and judged based on the detection results.

2. The method for detecting defects in ultra-thin inner layer composite pipes without pipe end blind zones as described in claim 1, characterized in that, The circumference of the composite pipe is divided into several sectors in the circumferential direction. For each sector, a series of jet-coupled ultrasonic testing units that meet the circumferential resolution requirements for flaw detection are arranged to carry out the detection. The flaw detection of the entire composite pipe, including the pipe end parts in all sectors, is completed by using the axial reciprocating working mode of the composite pipe.

3. An apparatus for a method of detecting defects in an ultra-thin inner layer composite tube without a tube end blind zone as described in claim 1 or 2, characterized in that, include: Base; The detection chamber is located at the center of the top surface of the base, with inlet and outlet corresponding to the center of its two sides; A jet-coupled water circulation chamber is a cylindrical structure that can be vertically mounted inside the detection box. Its bottom has inlet and outlet ports and corresponding inlet and outlet pipes. Several jet-coupled ultrasonic detection units are installed circumferentially on the top surface of the chamber. These units have the same central angle, forming a fan-shaped distribution, and are evenly spaced along the axial direction of the chamber. Adjacent units maintain a certain axial and radial distance. Each jet-coupled ultrasonic detection unit is an ultrasonic detection channel. A coupling water circulation tank is installed inside the base and is connected to the inlet and outlet pipes of the jet detection coupling water circulation chamber through inlet and outlet water pipes; Two clamping mechanisms are respectively disposed on the top surface of the base on both sides of the detection box. The clamping mechanisms include: A pair of clamping rollers, arranged vertically, are positioned at the center of the top surface of the base at the inlet / outlet of the detection box. The drive mechanism is located on the top surface of the base on one side of the detection box; The gripper is connected to the drive mechanism and is driven by the drive mechanism to move left and right along the axial direction of the top surface of the base; the gripper and the gripping roller are located on the same axis.

4. The apparatus for the tube-end blind zone flaw detection method of the ultra-thin inner layer composite tube as described in claim 3, characterized in that, The jet detection coupled water circulation cavity is composed of several detection sub-cavities connected in series. Each detection sub-cavity has a mounting hole for installing a jet coupled ultrasonic detection unit, and a jet coupled ultrasonic detection unit is installed thereon. The mounting holes on each detection sub-cavity are arranged at equal intervals along the axial direction of the jet detection coupled water circulation cavity, and the central angles between each jet coupled ultrasonic detection unit are the same, so that the jet coupled ultrasonic detection units form a fan-shaped distribution. Each jet coupled ultrasonic detection unit is an ultrasonic detection channel.

5. The apparatus for the method of detecting defects in the inner layer of an ultra-thin composite tube without pipe end blind zone as described in claim 3, characterized in that, The drive mechanism includes: Two guide rails and their sliders are arranged in parallel on the top surface of the base; The mounting plate has sliders connected to the two guide rails at both ends of its bottom surface, and a connecting block is provided in the center of the bottom surface of the mounting plate; A ball screw, with its two ends arranged parallel to each other between two guide rails via bearing seats, and the screw nut on the ball screw connected to the connecting block; A drive motor, the output shaft of which is connected to one end of the ball screw.

6. The apparatus for the method of detecting defects in the inner layer of an ultra-thin composite tube without pipe end blind zone as described in claim 5, characterized in that, The drive motor is a servo motor.

7. The apparatus for the method of detecting defects in the inner layer of an ultra-thin composite tube without blind spots as described in claim 3, characterized in that, The axial spacing x between adjacent detection units is between 30 and 60 mm, and the radial spacing y is between 5 and 10 mm, or the central angle between adjacent detection units is between 5° and 15°.

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