Non-Destructive Automatic Inspection Device and Inspection Method for a Slag-Fiber-Manufactured Pressure Vessel

Abstract

A pressure vessel manufacturing and non-destructive automatic inspection method using slag fibers according to an embodiment of the present invention comprises: a pressure vessel formed with a central portion being cylindrical and both ends being dome-shaped; a slag fiber supply unit provided on one side of the pressure vessel for supplying slag fibers onto the pressure vessel; a winding unit for winding the slag fibers supplied through the slag fiber supply unit onto the outer surface of the pressure vessel in a predetermined direction; a fixing bracket provided on one end of the pressure vessel for fixing the pressure vessel to wind the pressure vessel with slag fibers; a chain link provided on the upper end of the fixing bracket for supporting the central portion of the pressure vessel in a mounted state after winding with slag fibers; a boss portion provided at the dome-shaped end of one end of the pressure vessel for opening and closing to supply or cut off hydrogen fuel; an ultrasonic inspection sensor provided on the upper end of the boss portion for inspecting defects in the pressure vessel; and a structure provided on one end of the boss portion, formed in a shape corresponding to the dome shape of the pressure vessel to fix the ultrasonic inspection sensor. Includes a sensor fixing bracket.

Description

Technology Field

[0001] The present invention relates to the manufacture of pressure vessels using slag fibers and a non-destructive automatic inspection technique. Specifically, it relates to a method for manufacturing pressure vessels using composite fibers having excellent properties such as heat resistance, chemical resistance, and fire resistance, and a non-destructive automatic inspection technique for inspecting for defects in pressure vessels. Background Technology

[0002] In general, glass fibers and carbon fibers have been primarily used for lightweight pressure vessels, and these are used as automotive and industrial pressure vessels.

[0003] The specific gravity of slag is 2.98 in a surface-dry saturated state, which is about 2.5 for glass fibers, 2.5 to 3 for basalt fibers, and about 1 for carbon fibers. Slag fibers have a higher specific gravity than carbon fibers and have a specific gravity similar to that of glass and basalt fibers.

[0004] The tensile strength of slag fibers has an average value of about 3,000 MPa, which is similar to the strength values ​​of basalt fibers and glass fibers, and it is judged that they have sufficient strength for industrial application.

[0005] Carbon fiber is expected to cost 15,000 won per kg, glass fiber 2,000 won per kg, basalt fiber 2,000 won per kg, and slag fiber 1,000 won per kg, resulting in a 15-fold price difference compared to carbon fiber.

[0006] Therefore, the present invention is a technology that utilizes slag fibers possessing these physical characteristics and cost advantages for the production of pressure vessels, and is intended to be utilized for the expansion of the hydrogen vessel industry.

[0007] In particular, hydrogen composite containers intended for application in transportation equipment and various general industries are used in products widely used by the general public, such as hydrogen electric vehicles, hydrogen charging stations, drones, and fuel cells. Therefore, if safety is not properly ensured, it will face public backlash, making it difficult to build basic infrastructure and revitalize the hydrogen economy.

[0008] As the hydrogen economy is still in its early stages, it is urgent to alleviate the public's vague anxieties. In the railway vehicle sector, development is underway with the goal of developing hydrogen fuel cell railway vehicles by 2024 and commercializing them by 2025. Given that railway vehicles, intended for mass transport within public transportation, prioritize product safety, safety verification technology is the most urgent requirement not only for development products but also for commercialized products.

[0009] Accordingly, the government is proposing improvement measures for hydrogen composite containers, which are widely used for hydrogen storage, including establishing new manufacturing and internal management standards to prevent cracks, introducing a safety evaluation system involving experts, conducting annual precision inspections, implementing real-time dual monitoring, and expanding component certification.

[0010] As such, while efforts are being made to legislate safety inspection standards across all hydrogen-related fields, technologies aimed at ensuring safety through real-time inspection are currently limited to importing foreign technologies or conducting only basic research.

[0011] Therefore, research is required on the fabrication of pressure vessels using slag fibers tailored for dedicated containers for hydrogen vehicles, as well as on safety diagnostic systems through inspection and monitoring to ensure safety during the fabrication of pressure vessels, and on test methods and standards for safety inspections. Prior art literature

[0012] Korean Patent Publication No. 10-2020-0003441 The problem to be solved

[0013] The purpose of the present invention is to provide a pressure vessel manufacturing method using slag fibers and a non-destructive automatic inspection technique that can manufacture various pressure vessels using slag fibers having heat resistance, fire resistance, and chemical resistance properties, thereby being environmentally friendly and reducing manufacturing costs.

[0014] In addition, the purpose is to provide a pressure vessel manufacturing and non-destructive automated inspection technique using slag fibers that can improve stability and minimize the defect rate of pressure vessels by verifying the presence or absence of defects occurring during manufacturing in advance.

[0015] The problems that the present invention aims to solve are not limited to those mentioned above, and other problems that the present invention aims to solve that are not mentioned herein will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0017] A pressure vessel manufacturing device using slag fibers according to an embodiment of the present invention comprises: a pressure vessel formed with a central portion being cylindrical and both ends being dome-shaped; a slag fiber supply unit provided on one side of the pressure vessel for supplying slag fibers onto the pressure vessel; a winding unit for winding the slag fibers supplied through the slag fiber supply unit onto the outer surface of the pressure vessel in a predetermined direction; a fixing bracket provided on one end of the pressure vessel for fixing the pressure vessel to wind the pressure vessel with slag fibers; a chain link provided on the upper end of the fixing bracket for supporting the central portion of the pressure vessel in a mounted state after winding with slag fibers; a boss portion provided at the dome-shaped end of one end of the pressure vessel for opening and closing to supply or cut off hydrogen fuel; an ultrasonic inspection sensor provided on the upper end of the boss portion for inspecting defects in the pressure vessel; and a sensor fixing bracket provided on one end of the boss portion, formed in a shape corresponding to the dome shape of the pressure vessel to fix the ultrasonic inspection sensor. It is possible.

[0018] A non-destructive automatic inspection technique for pressure vessels using slag fibers according to an embodiment of the present invention may include: a first step of inspecting at least one damaged vessel portion among a nozzle portion, a nozzle to a side wall, a middle portion, a knuckle portion, and an insert 40 mm above, for each frequency including 1.5 MHz, 2.5 MHz, 3.5 MHz, and 5 MHz; a second step of comparing the measured values ​​of a normal vessel and a damaged vessel by intensively inspecting at least one edge portion among a left dome-shaped end, a right dome-shaped end, and a left dome-shaped outermost end of the pressure vessel based on the optimal frequency TRM extracted in the first step; and a third step of comparing the measured values ​​of a normal vessel and a damaged vessel by intensively inspecting the side wall portion of the pressure vessel based on the optimal frequency TRM extracted in the first step.

[0019] In a pressure vessel manufacturing apparatus using slag fibers according to one embodiment of the present invention, the slag fiber supply unit may be characterized by manufacturing slag fibers with a thickness of 8 to 20 μm and supplying them onto the pressure vessel. Effects of the invention

[0020] The present invention utilizes slag fibers having heat resistance, fire resistance, and chemical resistance properties to manufacture various pressure vessels, thereby providing the effects of being environmentally friendly and reducing manufacturing costs.

[0021] In addition, by checking for defects that may occur during the manufacturing of pressure vessels in advance, it has the effect of improving stability and minimizing the defect rate of pressure vessels. Brief explanation of the drawing

[0023] FIG. 1 is a drawing for explaining the manufacturing configuration of a pressure vessel using slag fibers according to an embodiment of the present invention. FIGS. 2 and 3 are perspective views illustrating a non-destructive automatic inspection configuration of a pressure vessel using slag fibers according to an embodiment of the present invention. Specific details for implementing the invention

[0024] Specific details regarding the problem to be solved, the means for solving the problem, and the effects of the invention as described above are included in the embodiments and drawings to be described below. The advantages and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the accompanying drawings.

[0025] Hereinafter, the present invention will be described in more detail with reference to the attached drawings.

[0027] FIG. 1 is a drawing for explaining the manufacturing configuration of a pressure vessel using slag fibers according to an embodiment of the present invention.

[0028] FIGS. 2 and 3 are perspective views illustrating a non-destructive automatic inspection configuration of a pressure vessel using slag fibers according to an embodiment of the present invention.

[0030] Referring to FIG. 1, a pressure vessel manufacturing and non-destructive automatic inspection device (100) using slag fibers according to an embodiment of the present invention may include a pressure vessel (110), a slag fiber supply unit (120), a winding unit (130), a fixing bracket (140), a chain link (150), a boss unit (160), an ultrasonic inspection sensor (170), and a sensor fixing bracket (180).

[0031] The pressure vessel (110) may have a central body portion configured in a cylindrical shape, and both ends of the body configured in a dome shape.

[0032] A slag fiber supply unit (120) may be provided on one side of the pressure vessel (110). It serves to supply slag fibers (S) onto the pressure vessel (110) in a predetermined direction.

[0033] More specifically, slag fibers (S) that are produced as a byproduct of the steel smelting process and have enhanced flame-retardant refractory performance are manufactured into a uniform thickness and then supplied to the pressure vessel (110).

[0034] It is preferable to use slag fibers (S) with a thickness within the range of 8 to 20 μm. However, if the thickness of the slag fibers (S) is less than 8 μm, it is not desirable because the strength is weak and the fiber breakage occurs frequently.

[0035] In addition, if the thickness is 20㎛ or more, the cutting short fibers may puncture, which is poor for handling, so it is preferable to use slag fibers (S) with a thickness within the above range.

[0036] The specific gravity of slag is 2.98 in a surface-dry saturated state, which is about 2.5 for glass fibers, 2.5 to 3 for basalt fibers, and about 1 for carbon fibers. Slag fibers have a higher specific gravity than carbon fibers and have a specific gravity similar to that of glass and basalt fibers.

[0037] The tensile strength of slag fibers has an average value of about 3,000 MPa, which is similar to the strength values ​​of basalt fibers and glass fibers, and it is judged that they have sufficient strength for industrial application.

[0038] Therefore, the surface of the pressure vessel (110) can be wrapped and protected from external fire by using slag fibers (S) that have these physical properties and cost advantages.

[0039] The winding section (130) may be provided on one side of the slag fiber supply section (120). It serves to wind the slag fiber (S) supplied through the slag fiber supply section (120) in a predetermined direction on the outer surface of the pressure vessel (110).

[0040] A fixed bracket (140) may be provided on one side of the end of the pressure vessel (110). It may be provided to connect the pressure vessel (110), which has a cylindrical central portion and dome-shaped ends on both sides, with the winding portion (130). It serves to fix the pressure vessel (110) for winding with slag fibers (S).

[0041] A chain link (150) may be provided on the top of the fixed bracket (140). It serves to support the central part of the pressure vessel (110) in a mounted state after being wound with slag fibers (S).

[0042] The boss (160) may be provided at the dome-shaped end of one end of the pressure vessel (110). It serves to open and close so that hydrogen fuel is supplied or cut off.

[0043] An ultrasonic inspection sensor (170) may be provided at the top of the boss portion (160). It serves to inspect for physical damage and defects in the pressure vessel (110).

[0044] The sensor fixing bracket (180) may be provided on one side of the end of the boss portion (160). It is formed in a shape corresponding to the dome shape of the pressure vessel (110) and serves to fix the ultrasonic inspection sensor (170).

[0046] Meanwhile, the present invention is a technology that applies slag fibers, which possess physical properties and cost advantages, to the production of pressure vessels, and is intended to be utilized for the expansion of the hydrogen vessel industry. It provides a safety diagnostic system through inspection and monitoring to ensure safety during the production of lightweight pressure vessels in accordance with the Hydrogen Economy Activation Roadmap, as well as test methods and inspection standards for safety inspections.

[0047] In addition, it aims to revitalize the hydrogen economy, which is in the early stages of commercialization, and lay the foundation for growth into an advanced hydrogen economy nation.

[0048] The present invention relates to a method for inspecting physical damage to a pressure vessel boss that may cause hydrogen leakage from a pressure vessel without removing the pressure vessel from a vehicle.

[0049] A chain link (150) can be attached to the pressure vessel (110), and a sensor fixing bracket capable of fixing an ultrasonic inspection sensor (170) can be connected to the boss (160) to perform inspection.

[0050] The non-destructive technology used in this invention is widely used as a diagnostic method for power plants, aerospace, chemical plants, bridges, tanks, ships, pressure systems, etc. Accordingly, by applying ultrasound, a non-destructive technology, to precise defect diagnosis, the safety of hydrogen vehicles can be ensured through a low-cost, high-efficiency, and high-reliability diagnostic technology.

[0051] An example of a pressure-applicable non-destructive automatic inspection technique using slag fibers according to the present invention is as follows.

[0052] 1) Phase 1: Damaged container inspection with a total of 4 frequencies (1.5, 2.5, 3.5 & 5 MHz)

[0053] 2) Phase 2: Intensive inspection of pressure vessel edges (using 2.5MHz TRM)

[0054] 3) Phase 3: Intensive inspection of pressure vessel sidewalls (using 2.5MHz TRM)

[0056] In the first step above, the TRM frequency can be compared based on the normal container.

[0057] As a result of comparing TRM frequencies, it was confirmed that for pressure vessels, a TRM with a frequency of 1.5 MHz is the most optimal.

[0058] For the dome-shaped end of the pressure vessel, it can be confirmed that a TRM of 2.5 MHz is the most optimal.

[0059] This is because the dome-shaped end has a thinner wall thickness, and using a TRM with a frequency of 2.5 MHz allows for higher spatial and temporal resolution compared to a TRM with a frequency of 1.5 MHz.

[0060] This improved resolution can be confirmed in the B-Scan images of previous inspection data, and due to the shorter wavelength of ultrasound at the corresponding frequency, the front and back wall echoes were seen much more clearly in the 2.5 MHz TRM compared to the 1.5 MHz TRM, and it can be confirmed that the main limitation of the 2.5 MHz TRM is at the bottom of the pressure vessel (400 mm insert section), where the thickness is greatest.

[0061] In the second step above, the results of the inspection focused on the left dome-shaped end of the pressure vessel for the 2.5 MHz TRM can be verified by comparing the normal vessel with the damaged vessel.

[0062] The thickness of the normal pressure vessel is confirmed to be 3.5 mm.

[0063] The thickness of the damaged pressure vessel is confirmed to be 4.5 mm.

[0064] It is unclear why defect-free containers are thinner.

[0065] In both pressure vessels, no echo can be observed at the interface between the CFRP and the liner.

[0066] In the second step above, the results of the inspection focused on the right dome-shaped end of the pressure vessel for the 2.5 MHz TRM can be verified by comparing the normal vessel with the damaged vessel.

[0067] The thickness of the normal pressure vessel is confirmed to be 8.1 mm.

[0068] The thickness of the damaged pressure vessel is confirmed to be 4.6 mm.

[0069] In the case of a normal pressure vessel, the liner can be checked in B-Scan.

[0070] In the case of a damaged pressure vessel, disbond occurs between the CFRP and the liner.

[0071] In the second step above, the results of the inspection focused on the left dome-shaped outermost end of the pressure vessel for the 2.5 MHz TRM can be verified by comparing the normal vessel with the damaged vessel.

[0072] The thickness of the normal pressure vessel is confirmed to be 8.75 mm.

[0073] The thickness of the damaged pressure vessel is confirmed to be 6.0 mm.

[0074] In the case of a normal pressure vessel, the liner can be checked in B-Scan.

[0075] In the case of a damaged pressure vessel, disbond occurs between the CFRP and the liner.

[0076] In the above third step, the entire C-Scan Map, which focuses on inspecting the sidewall portion of a normal pressure vessel for a 2.5 MHz TRM, can be viewed.

[0077] The blue color covering most of the C-Scan is determined to be a back wall echo reflected from inside the liner at a depth of ~14.5 mm.

[0078] The light blue color at the top of the C-Scan is determined to be disbond between the CFRP and the liner at a depth of 9.5 mm.

[0079] The light blue color at the bottom of the C-Scan is determined to be the thickness taper designed at the transition point between the side wall and the end of the cross.

[0080] Reflectors scattering in various colors are mostly small reflective surfaces with different depths, and horizontally observed striped reflections are caused by incomplete coupling between the transducer and the pressure vessel.

[0081] In the above third step, detailed analysis results by region can be confirmed by focusing on the side wall portion of a normal pressure vessel for a 2.5 MHz TRM.

[0082] The screenshot on the left above is an example of a high-quality area with a displayed depth of ~14.5mm, showing the reflection of an undamaged boundary surface.

[0083] The screenshot on the right above shows an example of an area suspected of disbond at a depth of ~9 mm.

[0084] In the above third step, the entire C-Scan Map, which focuses on inspecting the sidewall portion of the damaged pressure vessel for the 2.5Mhz TRM, can be viewed.

[0085] The blue color covering most of the C-Scan is determined to be a back wall echo reflected from inside the liner at a depth of ~14.5 mm.

[0086] The light blue color at the top of the C-Scan is determined to be disbonded between the CFRP and the liner at a depth of 9.5 mm, and this occupies a larger area compared to the normal container.

[0087] Some areas suspected of disbonding are observed along the perimeter, even in the lower part of the pressure vessel.

[0088] In addition to the scattered signs observed in normal vessels, what appears to be a small disbond is identified along the side wall for an intermediate length.

[0089] In the above third step, detailed analysis results by region of the damaged sidewall portion of the pressure vessel for the 2.5Mhz TRM can be checked.

[0091] The results of the verification test of an exemplary embodiment of the analysis and data collection of the ultrasonic-based defect detection system according to the present invention are as follows.

[0092] 1) As a result of conducting inspections on normal containers and containers suspected of being damaged, it was confirmed that TRMs with frequencies of 1.5 MHz and 2.5 MHz can be most effectively utilized for inspection.

[0093] 2) In particular, for the side walls of pressure vessels, it was confirmed that a TRM with a frequency of 1.5 MHz is the most optimal, and it can be confirmed that for thicker walls at that location, the lowest frequency TRM that can definitely penetrate into the interior is required.

[0094] 3) In particular, it can be confirmed that the 2.5 MHz Aqualene Delay Line can be in close contact along the double curved surface of the dome-shaped end of the pressure vessel.

[0095] 4) The side walls of the pressure vessel were inspected using a separately manufactured jig and an ODI encoder, and the dome-shaped ends were inspected in a free form.

[0096] 5) The measurement results of Type 4 pressure vessels for hydrogen vehicles reveal various characteristics as follows, and by propagating ultrasound into the pressure vessel, the high quality area can be confirmed.

[0097] In addition, low-quality areas where reflection occurs at various depths inside the pressure vessel and disbond areas between the CFRP and the liner can be identified through ultrasound reflected at the interface.

[0098] 6) It can be confirmed that the quality of a pressure vessel can be rapidly screened by quickly identifying the internal condition of the pressure vessel through a 2D-Array type ultrasonic C-Scan.

[0099] 7) The clear color coding of ToF (depth) C-Scan enables rapid identification of undamaged and disbonded interfaces, thereby allowing for evaluation for quality control regarding product acceptance and rejection in the pressure vessel production process.

[0101] Through this, the present invention can provide a safety diagnostic system through inspection and monitoring to ensure the safety of pressure vessels using slag fibers in accordance with the hydrogen economy activation roadmap, as well as test methods and inspection standards for safety inspections.

[0102] In addition, jigs and sensors can be easily mounted on the pressure vessel during inspection.

[0103] In addition, it has the effect of localizing equipment by securing technology that is currently dependent on imports, and raising awareness of the safety of hydrogen usage among the public who are sensitive to safety.

[0104] In addition, it has the effect of revitalizing the hydrogen economy, which is in the early stages of commercialization, and laying the foundation for growth into an advanced hydrogen economy nation.

[0106] As described above, although an embodiment of the present invention has been explained by limited embodiments and drawings, the embodiment of the present invention is not limited to the described embodiment, and various modifications and variations are possible from this description by those skilled in the art to which the present invention pertains. Accordingly, an embodiment of the present invention should be understood only by the claims described below, and all equivalent or analogous variations thereof shall be considered to be within the scope of the inventive concept. Explanation of the symbols

[0108] 100: Pressure vessel manufacturing and non-destructive automatic inspection device using slag fibers 110: Pressure vessel 120: Slag fiber supply unit 130: Winding section 140: Fixing bracket 150: Chain Link 160: Boss 170: Ultrasonic inspection sensor 180: Sensor mounting bracket S: Slag fiber

Claims

Claim 1 A non-destructive automatic inspection device for non-destructively inspecting for defects in a pressure vessel manufactured using slag fibers by means of an ultrasonic method, comprising: a fixing bracket for fixing one end of the pressure vessel to be inspected; a chain link provided at the top of the fixing bracket for supporting the central part of the pressure vessel; an ultrasonic inspection sensor provided on one side of a boss part provided at the dome-shaped end of the pressure vessel for inspecting for defects in the pressure vessel; and a sensor fixing bracket formed in a shape corresponding to the boss part for fixing the ultrasonic inspection sensor. Claim 2 A non-destructive automatic inspection method for a pressure vessel manufactured using slag fibers, comprising: a first step of inspecting at least one damaged vessel portion among a nozzle portion, a nozzle to side wall, a middle portion, a knuckle portion, and an insert 40 mm above using a TRM for each of a plurality of frequencies including 1.5 MHz, 2.5 MHz, 3.5 MHz, and 5 MHz, and deriving an optimal frequency TRM by comparing the TRMs of the plurality of frequencies with respect to a normal vessel; a second step of comparing the measured values ​​of a normal vessel and a damaged vessel by intensively inspecting at least one edge portion among the left dome-shaped end, the right dome-shaped end, and the outermost left dome-shaped end of the pressure vessel based on the optimal frequency TRM derived in the first step; and a third step of comparing the measured values ​​of a normal vessel and a damaged vessel by intensively inspecting the side wall portion of the pressure vessel based on the optimal frequency TRM derived in the first step. Claim 3 delete

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