RLP observation device for LNG ammonia gas test and use method of RLP observation device

Abstract

The invention relates to an RLP observation device for an LNG ammonia gas test, a film type storage tank is provided with a valve port communicated with the interior of the film type storage tank, the observation device comprises an observation window and a detection system, the detection system is connected with the valve port through a ball valve, the detection system is provided with an exhaust valve, the periphery of the observation window is provided with a sticking part, and the sticking part is connected with the valve port through a ball valve. The pasting part is provided with a bottom vacuum mud sealing layer and a surface adhesive tape layer, and a color developing adhesive tape is arranged in the middle of the bottom of the observation window. During use, due to the design of the observation window, an inspector can capture the color change of the color developing adhesive tape in the pasting area in all directions, and a visual and clear observation view field is provided. The detection system realizes accurate measurement of the ammonia concentration of each standard leakage point area, and according to the exhaust valve disclosed by the invention, when the color developing adhesive tape does not react, ammonia nitrogen mixed gas can smoothly circulate in an air passage in an observation device, so that the detection efficiency of an ammonia gas test is improved. Meanwhile, the firm connection of the device is ensured through the sticking part, and the problem of falling in the test process is effectively prevented.

Description

Technical Field

[0001] The invention relates to the technical field of nondestructive testing, in particular to an RLP observation device for LNG ammonia testing and a use method thereof. Background Art

[0002] Membrane type cryogenic storage tanks are key equipment for the shipping industry to achieve long-distance and efficient transportation of cryogenic liquefied gas. Vessels equipped with membrane type cryogenic storage tanks have many advantages, such as high utilization of cargo space, low evaporation rate, relatively low maintenance cost, and high safety. Currently, membrane type cryogenic storage tanks are the mainstream choice in the liquefied gas shipping industry.

[0003] The membrane tank is composed of primary and secondary shielding layers, and primary and secondary insulation spaces (refer to Figure 1 ), the reason why the film-type cryogenic storage tank is called film-type is that the primary and secondary shielding layers are both made of film materials. The current mainstream film-type cryogenic storage tanks are divided into NO96 and Mark III. The primary and secondary shielding layers of the N096 type are both welded from 0.7mm thick Invar steel, and the primary shielding layer of the Mark III type is a 1.2mm thick corrugated plate, and the secondary shielding layer is a three-layer composite sheet about 0.6mm thick. The primary shielding layer is in direct contact with the cryogenic liquefied gas. Therefore, ensuring the airtightness of the primary and secondary shielding layers, especially the airtightness of the primary shielding layer, is the top priority of quality control in the construction and operation and maintenance stages of the tank.

[0004] Leak detection technology is a core technology to ensure the sealing performance of the primary and secondary shielding layers in key engineering structures, such as membrane-type onshore storage tanks and LNGC liquefied natural gas tankers. Its importance is self-evident. In the face of these complex engineering environments with extremely high safety requirements, the use of ammonia test to test the tightness of the primary shielding layer has become the industry's recognized gold standard. In this process, the observation device of the standard leak point (RLP) and its unique pasting method are the key links to ensure accurate detection.

[0005] However, the traditional standard leak point (RLP) pasting method has exposed many limitations in practical applications, such as limited pasting position, insufficient pasting strength, susceptibility to environmental factors, etc., and most importantly, it cannot directly and real-time measure the ammonia concentration, which to a certain extent restricts the comprehensiveness and accuracy of the detection work. Summary of the invention

[0006] The purpose of the present invention is to provide an improved RLP observation device for LNG ammonia testing and a method of using the same. Through the improvement of the structure and method, leakage detection can be carried out conveniently and quickly, while ensuring the accuracy of detection and improving the detection efficiency.

[0007] In order to achieve the above-mentioned purpose, the technical solution of the present invention is: an RLP observation device for LNG ammonia test, the observation device is arranged on a membrane type storage tank, and is characterized in that: the membrane type storage tank is provided with a valve port connected to the interior thereof, the observation device includes an observation window and a detection system, the detection system and the valve port are connected by a ball valve, an exhaust valve is provided on the detection system, an adhesive portion is provided around the observation window, the adhesive portion is provided with two adhesive layers, namely a vacuum sealing mud layer at the bottom and a tape layer on the surface, and a color developing tape is provided at the middle position at the bottom of the observation window.

[0008] Preferably, the observation window is formed by gluing 3-6 layers of transparent acrylic plates together, and the observation window is in the shape of a triangle, a quadrilateral or a pentagon.

[0009] A method for using an RLP observation device for LNG ammonia testing, characterized in that the use steps are as follows: a. First confirm the standard leakage point (RLP) status to confirm that the standard leakage point (RLP) observation device can be installed and used; b. Paste the standard leakage point (RLP) observation device so that the RLP observation device is sealed and firmly pasted to the film type storage tank, and the color developing tape is pasted on the RLP reserved weld; c. After injecting ammonia nitrogen mixed gas into the film type storage tank, observe the changes in the color developing tape. If the color developing tape does not change or only partially changes color for more than 24 hours, it is necessary to perform degassing treatment; d. Measure the RLP concentration to ensure that the ammonia concentration reaches the specified standard.

[0010] Preferably, in step a, the length of the standard leakage point (RLP) is accurately measured, with an allowable length range of 25 mm-30 mm, and the opening width of the standard leakage point (RLP) is measured, with an allowable width range of 1 mm-2 mm.

[0011] Further, in step b, the steps of attaching the standard leak point (RLP) observation device are as follows:

[0012] (1) Clean the area to be pasted;

[0013] (2) Stick the color developing tape on the reserved weld of the standard leak point (RLP);

[0014] (3) Stick the vacuum sealant around the reserved position of the standard leakage point (RLP) observation device to form a vacuum sealant layer;

[0015] (4) Align the observation window to the standard leak point (RLP) and stick it down;

[0016] (5) A layer of tape is pasted on the outer periphery of the observation window so that the tape layer overlaps with the vacuum sealing layer to complete the pasting of the observation window.

[0017] In step c, the deflation process is as follows:

[0018] (1) Use a hose of sufficient length, with one end connected to the exhaust valve of the detection system and the other end connected to the outside of the membrane tank compartment;

[0019] (2) Gently open the exhaust valve of the detection system to ensure that the gas can be released slowly and safely;

[0020] (3) During the deflation process, continue to observe the color change of the color-developing tape to avoid missing the key color change point;

[0021] (4) Once the color-developing tape is found to have completely changed color, immediately close all valves of the detection system to ensure that the gas does not leak out.

[0022] In step d, during the ammonia test spraying process, if a standard leak point (RLP) is found

[0023] If the color of the color-developing tape on the RLP becomes lighter, connect the ammonia concentration detector to the detection system port to measure the ammonia concentration. If the concentration does not meet the standard, increase the injected ammonia concentration or repeat the venting operation to make the concentration at the RLP meet the standard.

[0024] In step d, during the ammonia test spray inspection process, once a standard leak point (RLP) is found

[0025] If the color of the chromogenic tape on your computer starts to fade, take the following actions immediately:

[0026] (1) Accurately connect the ammonia concentration detector to the designated port of the detection system;

[0027] (2) Start the ammonia concentration detector and prepare to perform ammonia concentration detection;

[0028] (3) Conduct actual measurements of ammonia concentration and carefully record the results;

[0029] (4) If the measurement results show that the ammonia concentration does not meet the preset standard, appropriate measures should be taken according to the specific situation; if the concentration is much lower, consider increasing the injected ammonia concentration; if it is only slightly lower than the standard, repeat the venting operation to increase the ammonia concentration in the RLP area until it reaches the specified standard;

[0030] (5) After adjusting the ammonia concentration, it is necessary to test again to confirm that the concentration has reached the standard and observe whether the color of the color-developing tape has returned to normal to ensure the accuracy and reliability of the test results.

[0031] Compared with the prior art, the technical solution of the present invention not only improves the overall technical solution, but also includes many improvements in details. Specifically, it has the following beneficial effects:

[0032] 1. The improved scheme of the present invention is that the film-type storage tank is provided with a valve port connected to the inside thereof, the observation device includes an observation window and a detection system, the detection system and the valve port are connected through a ball valve, an exhaust valve is provided on the detection system, a pasting portion is provided around the observation window, and a color developing tape is provided at the middle position of the bottom of the observation window. Through the observation window, the color of the color developing tape can be intuitively and clearly understood in real time, so as to dynamically grasp the change of ammonia concentration, and the detection process is more accurate and efficient;

[0033] 2. In the technical solution of the present invention, the adhesive part is provided with two adhesive layers, namely, a vacuum sealing layer at the bottom and an adhesive tape layer at the surface. The double adhesive layers here can ensure the firm bonding between the device and the RLP, prevent the problem of falling off during the experiment, and avoid gas leakage, thereby ensuring the authenticity and validity of the test data;

[0034] 3. In the method of the present invention, a deflation function is also designed. When the color developing tape does not react, it can be quickly started to allow the ammonia nitrogen mixed gas to flow smoothly and fully in the airway inside the observation device, breaking the limitation of the traditional independent gas chamber and further improving the detection efficiency of the ammonia test;

[0035] 4. The present invention has a simple structure, reasonable layout, easy use, high detection accuracy, good detection effect, and is easy to promote and utilize. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of the membrane type storage tank of the present invention.

[0037] Figure 2 It is a schematic diagram of the structure of the observation device of the present invention.

[0038] Figure 3 It is a schematic diagram of the structure of the observation device of the present invention in use state.

[0039] Reference numerals:

[0040] 1. Membrane storage tank, 2. Observation window, 3. Detection system, 4. Ball valve, 5. Vacuum sealing layer, 6. Tape layer, 7. Color developing tape, 8. Welding seam;

[0041] 11 main shielding layer, 12 secondary shielding layer, 13 steel plate, 14 ball valve;

[0042] 51 Vacuum sealing reserved area. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be described clearly and completely below 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 creative work are within the scope of protection of the present invention.

[0044] The present invention provides an RLP observation device for LNG ammonia test, which is arranged on a membrane type storage tank. Figure 2 The difference between the present invention and the prior art lies in that: a valve port communicating with the interior of the film-type storage tank 1 is provided on the film-type storage tank, the observation device comprises an observation window 2 and a detection system 3, the detection system and the valve port are connected via a ball valve 4, an exhaust valve is provided on the detection system, an adhesive portion is provided around the observation window, the adhesive portion is provided with two adhesive layers, namely a vacuum sealing layer 5 at the bottom and a tape layer 6 on the surface, and a color developing tape 7 is provided at the middle position of the bottom of the observation window.

[0045] When in use, the observation device of the present invention has a more rigorous and sophisticated structure, which effectively avoids gas leakage and ensures the purity of the test environment and the accuracy of the data. The design of the observation window enables the inspector to capture the color changes of the color-developing tape in the pasting area in all directions, providing an intuitive and clear observation field of view, which is convenient for real-time grasp of the dynamic changes of the ammonia concentration. The detection system realizes the accurate measurement of the ammonia concentration in each standard leakage point (RLP) area. The exhaust valve of the present invention can be quickly started when the color-developing tape does not react, so that the ammonia-nitrogen mixed gas can flow smoothly in the internal airway of the observation device, further improving the detection efficiency of the ammonia test. At the same time, the adhesive part of the present invention ensures a firm connection between the device and the standard leakage point (RLP), effectively preventing the problem of falling off during the test.

[0046] Example 1

[0047] In this embodiment, a valve port communicating with the inside of the film-type storage tank is provided on the film-type storage tank, and the observation device includes an observation window 2 and a detection system 3. The detection system and the valve port are connected by a ball valve 14. The detection system is provided with an exhaust valve. An adhesive portion is provided around the observation window. The adhesive portion is provided with two adhesive layers, namely, a vacuum sealing layer 5 at the bottom and a tape layer 6 on the surface. A color developing tape 7 is provided at the middle of the bottom of the observation window. The observation window is formed by bonding 3-6 layers of transparent acrylic plates, and the observation window 2 is triangular, quadrilateral or pentagonal. The quadrilateral here is mostly square or rectangular.

[0048] Specifically, the observation window is made of 5 layers of acrylic sheets, which, with their excellent transparency, durability and impact resistance, have become the key elements in building this device. During the bonding process, the standard of vacuum box bonding in the field of vacuum box testing is strictly followed, and precise bonding technology and high-quality adhesives are used to ensure that the connection between each piece of acrylic sheet is both firm and tight. This stable construction method not only enhances the overall aesthetics of the device, but also enables it to maintain a high degree of stability and durability in complex and changing use environments. The surface of these acrylic sheets is smooth and flawless, eliminating visual obstacles, ensuring the comprehensiveness and accuracy of the observation results, and effectively avoiding the problem of incomplete observation of color changes due to limited observation angles.

[0049] In practice, the detection system is connected to the valve port through a ball valve 14. The detection system is provided with an exhaust valve. In a specific situation, when the color-developing tape fails to trigger the expected reaction for a long time (more than 24 hours), the system can extend the connecting pipe outside the cabin to perform the deflation operation. During this slow deflation process, ammonia is accurately guided to the complex airway network inside the standard leak point (RLP), forming a stable flow path, ensuring that ammonia can flow fully and fully act on the color-developing tape, thereby causing its color change, providing a reliable basis for the determination of the detection results.

[0050] Furthermore, there are adhesive parts around the observation window, and the adhesive parts are provided with two adhesive layers, namely the vacuum seal layer at the bottom and the tape layer on the surface. A color developing tape is provided in the middle of the bottom of the observation window. The vacuum seal layer here is set in a specific area, which is set around the entire observation window. The seal here can fit tightly to form an efficient and reliable sealing barrier, thereby significantly improving the sealing performance and service life of the product. At the same time, a tape layer is provided on the surface of the vacuum seal layer. The tape has excellent adhesion and outstanding environmental adaptability, and can maintain a stable adhesive effect under various working conditions. Through the organic combination with the vacuum seal, the tape effectively enhances the adhesive firmness and standardization of the standard leakage point (RLP) observation window, ensuring the stability and safety of the product structure.

[0051] Example 2

[0052] This embodiment describes a method for using an RLP observation device for LNG ammonia testing, and the steps of use are as follows: a. First, confirm the state of the standard leakage point (RLP), which refers to the weld 8 here, and confirm that the standard leakage point (RLP) observation device can be installed and used; b. Paste the standard leakage point (RLP) observation device so that the standard leakage point (RLP) observation device is sealed and firmly pasted to the membrane type storage tank, and the color developing tape is pasted on the reserved weld of the standard leakage point (RLP); c. After injecting ammonia nitrogen mixed gas into the membrane type storage tank, observe the changes in the color developing tape. If the color developing tape has not changed or has only partially changed color for more than 24 hours, it is necessary to perform degassing treatment to allow the ammonia nitrogen mixed gas to fully flow in the airway in the membrane type storage tank; d. Measure the concentration of the standard leakage point (RLP) to ensure that the ammonia concentration reaches the specified standard.

[0053] In step a, the length of the standard leakage point (RLP) is accurately measured, and the allowable length range is 25mm-30mm, preferably 26-28mm. The opening width of the standard leakage point (RLP) is measured, and the allowable width range is 1mm-2mm.

[0054] Specifically, all standard leak points (RLP) are obtained by stopping welding at a distance of 30mm on the weld. Before pasting the standard leak point (RLP) observation device to the standard leak point (RLP), the length of the standard leak point (RLP) must be accurately measured using a measuring tool to ensure that it meets the design specifications. Any length deviation beyond the allowable range may have an adverse effect on the installation and use of the standard leak point (RLP) observation device. A comprehensive and detailed inspection of the opening status of the standard leak point (RLP) is also required. The opening width of the standard leak point (RLP) should be moderate and should not be too narrow or too wide. An opening that is too narrow may reduce the passing rate of the ammonia nitrogen mixture, resulting in incomplete reaction; while an opening that is too wide may reduce the tightness of the combination between the observation device and the standard leak point (RLP), affecting the accuracy and stability of the observation.

[0055] In step b, the steps for attaching the RLP observation device are as follows:

[0056] (1) Clean the area to be pasted;

[0057] (2) Stick the color developing tape on the reserved weld of the standard leak point (RLP);

[0058] (3) sticking the vacuum sealant around the reserved position of the standard leakage point (RLP) observation device (i.e., the vacuum sealant reserved area 51) to form a vacuum sealant layer;

[0059] (4) Align the observation window to the standard leak point (RLP) and stick it down;

[0060] (5) A tape layer 6 is pasted on the outer periphery of the observation window so that the tape layer overlaps with the vacuum sealing layer, and the observation window is pasted.

[0061] In step c, the deflation process is as follows:

[0062] (1) Use a hose of sufficient length, with one end connected to the exhaust valve of the detection system and the other end connected to the outside of the membrane tank compartment;

[0063] (2) Gently open the exhaust valve of the ammonia concentration detection system to ensure that the gas can be released slowly and safely. Specifically, change the gas flow formula: Q = P*A / 0.98, P is the pressure in millibars, A is the cross-sectional area of ​​the tube in square centimeters. If the calculated value of Q is within the range of 1±0.1, it means that the body is released slowly and safely;

[0064] (3) During the deflation process, continue to observe the color change of the color-developing tape to avoid missing the key color change point;

[0065] (4) Once the color-developing tape is found to have completely changed color, immediately close all valves of the detection system to ensure that the gas does not leak out.

[0066] In step d, during the ammonia test spray detection process, if the color of the color-developing tape on a certain standard leak point (RLP) is found to become lighter, connect the ammonia concentration detector to the detection system port to measure the ammonia concentration. If the concentration does not meet the standard (the concentration standard is 25,000 PPM), increase the injected ammonia concentration or repeat the venting operation to make the concentration at the standard leak point (RLP) meet the standard.

[0067] In step d, during the ammonia test spray inspection process, if the color of the color-developing tape on a standard leak point (RLP) shows signs of fading, the following measures should be taken immediately:

[0068] (1) Accurately connect the ammonia concentration detector to the designated port of the detection system;

[0069] (2) Start the ammonia concentration detector and prepare to perform ammonia concentration detection;

[0070] (3) Conduct actual measurements of ammonia concentration and carefully record the results;

[0071] (4) If the measurement results show that the ammonia concentration does not meet the preset standard, appropriate measures should be taken according to the specific situation; if the concentration is much lower, consider increasing the injected ammonia concentration; if it is only slightly lower than the standard, repeat the venting operation to increase the ammonia concentration in the RLP area until it reaches the specified standard;

[0072] (5) After adjusting the ammonia concentration, it is necessary to test again to confirm that the concentration has reached the standard and observe whether the color of the color-developing tape has returned to normal to ensure the accuracy and reliability of the test results.

[0073] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to the above descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. An RLP observation device for LNG ammonia test, the observation device is arranged on a membrane type storage tank, characterized in that: The membrane type storage tank is provided with a valve port connected to the interior thereof, the observation device comprises an observation window and an ammonia concentration detection system, the ammonia concentration detection system and the valve port are connected via a ball valve, the ammonia concentration detection system is provided with an exhaust valve, adhesive portions are provided around the observation window, the adhesive portions are provided with two adhesive layers, namely a vacuum sealing mud layer at the bottom and a tape layer on the surface, and a color developing tape is provided at the bottom middle position of the observation window.

2. The RLP observation device for LNG ammonia test according to claim 1, characterized in that: The observation window is made of 3-6 layers of transparent acrylic plates bonded together, and the observation window is in the shape of a triangle, a quadrilateral or a pentagon.

3. The method for using the RLP observation device for LNG ammonia test according to claim 1, characterized in that: The steps for use are as follows: a. First confirm the status of the standard leakage point and confirm that the RLP observation device can be installed and used; b. Paste the standard leakage point observation device so that it is sealed and firmly pasted to the membrane type storage tank, and the color developing tape is pasted on the reserved weld of the standard leakage point; c. After injecting ammonia nitrogen mixed gas into the membrane type storage tank, observe the changes of the color developing tape. If the color developing tape has not changed or has only partially changed color for more than 24 hours, it is necessary to deflate the tape so that the ammonia nitrogen mixed gas can flow fully in the airway in the membrane type storage tank; d. Measure the concentration of the standard leakage point to ensure that the ammonia concentration meets the specified standard.

4. The method for using the RLP observation device for LNG ammonia test according to claim 3 is characterized in that: In step a, the length of the standard leakage point is accurately measured, and the allowable length range is 25mm-30mm. The opening width of the standard leakage point is measured, and the allowable width range is 1mm-2mm.

5. The method for using the RLP observation device for LNG ammonia test according to claim 3 is characterized in that: In step b, the steps for pasting the standard leak point observation device are as follows: (1) Clean the area to be pasted; (2) Stick the color-developing tape on the reserved weld at the standard leakage point; (3) Stick the vacuum sealant around the reserved position of the standard leakage point observation device to form a vacuum sealant layer; (4) Align the observation window to the standard leakage point and stick it down; (5) Stick a layer of tape on the outer periphery of the observation window so that the tape layer overlaps with the vacuum seal layer to complete the sticking of the observation window.

6. The method for using the RLP observation device for LNG ammonia test according to claim 3, characterized in that: In step c, the deflation process is as follows: (1) Use a hose of sufficient length, with one end connected to the exhaust valve of the detection system and the other end connected to the outside of the membrane tank compartment; (2) Gently open the exhaust valve of the detection system to ensure that the gas can be released slowly and safely; (3) During the deflation process, continue to observe the color change of the color-developing tape to avoid missing the key color change point; (4) Once the color-developing tape is found to have completely changed color, immediately close all valves of the detection system to ensure that the gas does not leak out.

7. The method for using the RLP observation device for LNG ammonia test according to claim 3, characterized in that: In step d, during the ammonia test spray detection process, if the color of the color-developing tape on a certain standard leakage point is found to become lighter, the ammonia concentration detector is connected to the detection system port to measure the ammonia concentration. If the concentration does not meet the standard, the injected ammonia concentration is increased or the venting operation is repeated to make the concentration at the standard leakage point meet the standard.

8. The method for using the RLP observation device for LNG ammonia test according to claim 3, characterized in that: In step d, during the ammonia test spray detection process, if the color of the color-developing tape on a standard leak point shows signs of fading, the following measures should be taken immediately: (1) Accurately connect the ammonia concentration detector to the designated port of the detection system; (2) Start the ammonia concentration detector and prepare to conduct ammonia concentration detection; (3) Conduct actual measurements of ammonia concentration and carefully record the results; (4) If the measurement results show that the ammonia concentration does not reach the preset standard, appropriate measures need to be taken according to the specific situation; if the concentration is much lower, consider increasing the injected ammonia concentration; if it is only slightly lower than the standard, repeat the venting operation to increase the ammonia concentration in the standard leakage point area until it reaches the specified standard; (5) After adjusting the ammonia concentration, it is necessary to test again to confirm that the concentration has reached the standard and observe whether the color of the color-developing tape has returned to normal to ensure the accuracy and reliability of the test results.

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