Installation method of low-temperature pipe cabin-penetrating type expansion joint

Abstract

The invention relates to the technical field of ship manufacturing, in particular to an installation method of a low-temperature pipe cabin-penetrating type expansion joint. Firstly, a low-temperature pipe is prepared to be installed on a deck in a penetrating mode; measuring the total length size of an expansion bend and the size of a corrugated section in the expansion joint, comparing with original data during design, and if the difference between the data at the moment and the original data exceeds a preset limit, replacing a new expansion joint; then all parts in the expansion joint are welded and connected together, and the total length size of the expansion bend and the size of the corrugated section in the expansion joint are measured again and compared with the original data; then the expansion joint is welded and fixed on the low-temperature pipe and the deck, and the total length size of the expansion bend and the size of the corrugated section in the expansion joint are measured again and compared with the original data; therefore, the problem that in the prior art, the expansion joint is not managed and controlled in the installation process, large prestress easily exists after installation is completed, even the size cannot be aligned, and the work amount is large when reworking is needed is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of shipbuilding, and particularly relates to an installation method for a low-temperature pipe through-hull expansion joint. Background Art

[0002] An expansion joint is an intermediate connecting piece commonly used in industry to withstand the expansion and contraction of pipe systems caused by thermal and cold temperature differences and mechanical vibrations. A marine low-temperature expansion joint is a component that can withstand thermal and cold stresses in an ultra-low temperature liquid environment to ensure the normal operation of a low-temperature pipe system, and its connection form with the pipeline is usually divided into a welded type and a flanged type. A large number of expansion joints are required during the construction of an LNG ship, such as a double-tie rod type expansion joint for the pipeline in the machinery room, a double-free type expansion joint for the low-temperature through-hull pipe on the deck surface, an expansion joint for the main engine and generator pipe system, etc. According to statistics, for a certain LNG ship type of our company, there are 47 expansion joints with pipe diameters in the range of DN40 - DN600 in the liquid dome area alone. Since the pipelines in this area are directly connected to the liquid cargo tank and need to withstand the flow of ultra-low temperature media, if the expansion joint deforms during the construction process, it will increase the risk of natural gas leakage in this area during the operation of the ship, posing a certain threat to the safety of the ship. Moreover, once the deformation amount exceeds the standard during the construction process, it is extremely difficult to rework.

[0003] The low-temperature pipe through-hull expansion joint includes four parts: a first liner plate, a circular ring support, an expansion bend, and a second liner plate. This expansion joint is installed at the position where the low-temperature pipe penetrates the deck. Generally, the first liner plate and the second liner plate are arranged in parallel at intervals, the expansion bend is located between the first liner plate and the second liner plate, and the circular ring support is located outside the first liner plate or the second liner plate for connection with the deck. The expansion bend is provided with a corrugated section, which can deform during use to compensate for the change amount caused by thermal expansion and contraction and absorb impacts and vibrations. The expansion joint generally arrives in a disassembled state, and multiple components are installed together during the construction process. Usually, the installation of the low-temperature pipe through-hull expansion joint is carried out along with the construction of the low-temperature pipe and the deck. Specifically, the first liner plate is welded to the low-temperature pipe, following the installation steps of the low-temperature pipe; the second liner plate and the circular ring support are welded and fixed to the deck, following the installation steps of the deck. When the deck and the low-temperature pipe are assembled, the first liner plate, the second liner plate, and the expansion bend are exactly installed opposite to each other.

[0004] However, during the installation process, errors will accumulate as the number of processes increases. During the installation of the expansion joint along with the cryogenic pipe and the deck, due to the installation of the deck and the cryogenic pipe, the errors will accumulate on the expansion joint, ultimately resulting in the distance between the first lining plate and the second lining plate of the expansion joint not meeting the design requirements, causing the expansion bend to be in a pre-tensioned or pre-compressed state, which affects the normal use of the expansion joint. Since the overall installation is already completed at this time, replacing it again will lead to complex processes and increased construction difficulty. Therefore, the earlier the damage of the expansion joint is discovered, the more the subsequent workload can be reduced. Summary of the Invention

[0005] In view of this, the present invention provides an installation method for a cryogenic pipe through-hull expansion joint to solve the problem in the prior art that there is no control during the installation process of the expansion joint, resulting in large prestress or even misalignment of dimensions after installation, which requires a large amount of work for rework.

[0006] An installation method for a cryogenic pipe through-hull expansion joint. First, prepare for the installation of the cryogenic pipe through the deck, provide sufficient installation space, and keep the cryogenic pipe concentric with the through-hull hole on the deck; measure the total length dimension and the corrugated section dimension of the expansion bend in the expansion joint and compare them with the original data during design. If the difference between the data and the original data exceeds the predetermined limit at this time, replace the expansion joint with a new one; then weld the various parts in the expansion joint together, and measure the total length dimension and the corrugated section dimension of the expansion bend in the expansion joint again and compare them with the original data. If the difference between the data and the original data exceeds the predetermined limit value at this time, remove the expansion joint and replace it with a new one; then weld the expansion joint to the cryogenic pipe and the deck, and measure the total length dimension and the corrugated section dimension of the expansion bend in the expansion joint again and compare them with the original data. If the difference between the data and the original data exceeds the predetermined limit value at this time, remove the expansion joint and replace it with a new one.

[0007] Further, when welding and fixing the expansion joint to the cryogenic pipe and the deck, first weld the circular support and the second lining plate to the deck, and then weld and fix the first lining plate to the cryogenic pipe.

[0008] Further, after welding and fixing the expansion joint to the cryogenic pipe and the deck, cut the temporary fixing rod on the expansion joint, and measure the total length dimension and the corrugated section dimension of the expansion bend after cutting the temporary fixing rod.

[0009] Further, after cutting the temporary fixing rod, smooth the cut.

[0010] Further, the total length dimension is the length between the two ends of the expansion bend along the axial direction. After the various parts of the expansion joint are welded together, the total length dimension is equal to the distance between the opposite plate surfaces of the first lining plate and the second lining plate.

[0011] Furthermore, during the process of welding the first lining plate and the second lining plate to the expansion bend respectively, the outer periphery of the expansion bend is axially divided into at least four sections, and when the partitions are welded in sequence, the starting point of the welding is at least 90 degrees away from the end point of the previous welding section.

[0012] Furthermore, during the process of welding the first lining plate and the second lining plate to the expansion bend respectively, a thermometer is used to measure the temperature between the welding layers and keep it below 150°C.

[0013] Furthermore, during the welding process of the first lining plate and the expansion bend, the distance between the first lining plate and the expansion bend is maintained to be no greater than 3 mm.

[0014] Furthermore, when welding the various parts in the expansion joint together, the first lining plate and the expansion bend are first welded together, and the welded first lining plate and the expansion bend are connected to the second lining plate and the annular support sleeve and installed on the cryogenic pipe, and then welded and assembled on the outer periphery of the cryogenic pipe.

[0015] The beneficial effects of the installation method of the cryogenic pipe through-cabin expansion joint of the present invention are as follows: in the process of installing the expansion joint, the present invention first maintains sufficient installation space to facilitate installation; by keeping the cryogenic pipe concentric with the through-cabin hole on the deck, the installation accuracy is maintained; by measuring the total length and the size of the corrugated section of the expansion bend and comparing them with the original data, the expansion bend is prevented from being damaged without knowing it in the initial stage of transportation or storage; by performing a second measurement after the expansion joint is welded, deformation due to excessive heat is avoided without knowing it during the welding process, and it is convenient to replace it in time when a problem occurs; then the expansion joint is welded to the cryogenic pipe and the deck to complete the final installation, and after the installation process is completed, the measurement is performed again and compared with the original data, and by performing multiple measurements at the stage where deformation may occur, it is ensured that whether the operation is deformed and whether it can continue to be used after the operation is completed is known at the first time, so as to avoid the problem of a large amount of rework caused by knowing whether it is qualified only after the overall installation is completed, thereby solving the problem in the prior art that there is no control during the installation of the expansion joint, resulting in a large prestress after the installation is completed, and even the size cannot be aligned, resulting in a large amount of work when rework is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a structural schematic diagram of the cryogenic pipe through-cabin expansion joint mentioned in the present invention;

[0018] Figure 2 is Figure 1 the partial enlarged view at X of

[0019] Figure 3 the structural schematic diagram of the expansion bend in the low-temperature pipe through-hull expansion joint mentioned in the present invention;

[0020] Figure 4 the process schematic diagram of the installation method of the low-temperature pipe through-hull expansion joint in the present invention;

[0021] Figure 5 the measurement schematic diagram (method 1) of the corrugated section size of the installation method of the low-temperature pipe through-hull expansion joint in the present invention;

[0022] Figure 6 the measurement schematic diagram (method 2) of the corrugated section size of the installation method of the low-temperature pipe through-hull expansion joint in the present invention;

[0023] Figure 7 the welding sequence schematic diagram of a pipe diameter expansion bend in the installation method of the low-temperature pipe through-hull expansion joint in the present invention;

[0024] Figure 8 the welding sequence schematic diagram of another pipe diameter expansion bend in the installation method of the low-temperature pipe through-hull expansion joint in the present invention.

[0025] The meanings of the reference numerals in the figure are as follows: 1, low-temperature pipe; 2, deck; 3, first lining plate; 4, expansion bend; 41, corrugated section; 42, temporary fixing rod; 5, second lining plate; 6, circular ring support; 7, fiberglass cloth; 8, pipeline insulation. Detailed implementation manners

[0026] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be described below through specific embodiments shown in the drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0027] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit this disclosure. The singular forms "a", "the" and "said" used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0028] It should be understood that although the terms first, second, third, etc. may be used in this disclosure to describe various information, such information should not be limited to these terms and should not be construed as indicating or implying relative importance. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "when" or "while" or "in response to determining".

[0029] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0030] In the description of the present invention, unless otherwise specified and defined, it should be noted that the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it may be a mechanical connection or an electrical connection, or it may be the communication inside two elements. It may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0031] In the following description, the suffixes such as "module", "component", or "unit" used to represent elements are only for the convenience of describing the present invention, and they do not have a specific meaning in themselves. Therefore, "module" and "component" can be used interchangeably.

[0032] For a better understanding of the technical solution of the present invention, the present invention will be described in detail below with reference to the drawings.

[0033] In Embodiment 1 of an installation method of a low-temperature pipe through-hull expansion joint (hereinafter referred to as the installation method) in the present invention:

[0034] This installation method is used to install the expansion joint at the through-hull position of the low-temperature pipe to compensate for the change caused by thermal expansion and contraction and absorb shock and vibration. Specifically, the installed structure is as Figure 1 and Figure 2As shown in the figure, a penetration hole for the low-temperature pipe 1 to pass through is provided on the deck 2, and the low-temperature pipe 1 is arranged through the penetration hole. An expansion joint is provided between the low-temperature pipe 1 and the deck 2. The expansion joint includes a first lining plate 3 for fixing on the low-temperature pipe 1 and a circular ring support 6 for fixedly connecting with the deck 2. A second lining plate 5 is provided on the side of the circular ring support 6 away from the deck 2. The first lining plate 3 and the second lining plate 5 are arranged at intervals relative to each other. An expansion bend 4 is provided between the first lining plate 3 and the second lining plate 5. A corrugated section 41 is provided on the expansion bend 4, which is convenient for absorbing vibration and thermal expansion and contraction. Of course, a fiberglass cloth 7 is also provided in the annular space formed between the second lining plate 5 and the circular ring support 6 to facilitate reducing stress concentration. In addition, pipeline insulation 8 is also provided at the end of the low-temperature pipe 1 and at the junction with the deck 2. The first lining plate 3, the expansion bend 4, the second lining plate 5, and the circular ring support 6 are separate components when leaving the factory. The first lining plate 3 is fixed to the low-temperature pipe 1, the first lining plate 3 is fixed to the expansion bend 4, the expansion bend 4 is fixed to the second lining plate 5, the second lining plate 5 is fixed to the circular ring support 6, and the circular ring support 6 is fixed to the deck 2 by welding. It should be noted that in order to protect the expansion bend 4, a temporary fixing rod 42 is provided outside the expansion bend 4 when leaving the factory, as Figure 3 shown. The expansion bend 4 can be strengthened through the temporary fixing rod 42, avoiding frequent deformation of the expansion bend 4 during transportation, which may damage its function. After the installation is completed, the temporary fixing rod 42 needs to be cut and removed.

[0035] In this embodiment, the NO.96 type LNG carrier is taken as an example for description. During the installation process, as Figure 4 shown, during the installation process of the expansion joint, first, preparations before installation need to be carried out to provide sufficient installation space. Since the expansion bend 4 is shipped from the manufacturer in the form of scattered parts, there is a long interval between shipping from the manufacturer and installation on the ship. During this period, deformation may occur. Therefore, before use, size measurement is carried out to facilitate screening out unqualified products and avoiding rework in the later stage. Specifically, before installation, measure the total length dimension of the expansion bend 4 in the expansion joint and the dimension of the corrugated section on the expansion bend 4 and compare them with the original data during design to judge whether the expansion bend 4 has deformed. If it has deformed, replace it with a new expansion bend 4 for use. The total length dimension of the expansion bend 4 refers to the length between the two ends of the expansion bend 4 along the axial direction, and the dimension of the corrugated section refers to the length dimension of the corrugated section 41. There are two ways, as Figure 5 shown, measure the distance L between the two farthest wave crests of a single bellows of the expansion joint, or as Figure 6 shown, measure the distance Y between the two ends of a single bellows of the expansion joint. It should be noted that only one of the measurement methods can be adopted during one installation process.

[0036] Before installation, it is necessary to ensure that all welding work of the deck through-penetrating parts in the small empty cabin of the liquid dome is completed and the jacks at the bottom of the pump tower are removed. Also, it is necessary to keep the penetration holes on the cryogenic pipe 1 and the deck 2 concentric. It should be noted that all parts of the expansion joint need to be installed on the cryogenic pipe 1, and the timing of installation on the cryogenic pipe 1 can be determined according to the actual situation. In this embodiment, the cryogenic pipe 1 at the installation position of the expansion joint is an open section, so it can be installed after the cryogenic pipe 1 is installed on the deck 2. If the pipe orifice of the cryogenic pipe 1 passes through the deck 2 and extends for a long length, each part of the expansion joint can be sleeved on the cryogenic pipe 1 before installing the cryogenic pipe 1. Specifically, during the installation process, first, the first liner plate 3 and the expansion bend 4 are welded and fixed together, and then the first liner plate 3 and the expansion bend 4, together with the second liner plate 5 and the ring support 6, are sleeved on the cryogenic pipe 1 for assembling the expansion joint on the cryogenic pipe 1. Since the coaxiality of the first liner plate 3 and the second liner plate 5 needs to be maintained during the installation process, this installation method can maintain the coaxiality of the first liner plate 3 and the second liner plate 5 through the cryogenic pipe 1, avoiding the situation where the expansion joint cannot be installed due to the unqualified coaxiality of the first liner plate 3 and the second liner plate 5 after the expansion joint is installed first. Of course, in other embodiments, the second liner plate and the ring support can also be welded into a small assembly first, and finally the two assemblies are respectively placed on the cryogenic pipe, reducing the welding operations after being sleeved on the cryogenic pipe and facilitating construction.

[0037] During the welding process, high temperature is required to melt the welding positions of the components, and such a high temperature may cause unnecessary deformation, resulting in a large deformation size of the finished product. Therefore, during the process of welding all parts of the expansion joint together, the amount of deformation needs to be reduced. Specifically, as Figure 7 and Figure 8 shown, during the process of welding the first liner plate 3 and the expansion bend 4 or the second liner plate 5 and the expansion bend 4 together, it is necessary to avoid their deformation. In this embodiment, the circular welds are welded in segments. When the pipe diameter is less than 150 mm, in the circumferential direction, the weld is divided into four segments and welded in the order of ABCD shown in the figure; when the pipe diameter is greater than 150 mm, in the circumferential direction, the weld is divided into eight segments and welded in the order of ABCDEGH shown in the figure. It should be noted that regardless of the number of segments for segmentation, during the welding process, the starting point of welding is at least 90 degrees away from the end point of the previous welding segment. Thus, during the welding process, the weld position is always cooling down, avoiding excessive heat accumulation in a certain segment.

[0038] During the welding process, the deformation of components is caused by the accumulation of a large amount of heat. Therefore, in addition to the above-mentioned segmented welding, the temperature at the welding site can also be monitored by means of temperature monitoring. Specifically, during the welding process, a thermometer is used to measure the interlayer temperature of the welding and keep it below 150°C. In addition, during the welding of the first liner plate 3 and the expansion elbow 4, the distance between the first liner plate 3 and the expansion elbow 4 is kept no more than 3 mm, that is, to prevent the edge of the first liner plate 3 from warping under the action of welding heat, thus affecting the quality of the final forming.

[0039] Since the welding process may cause deformation of the expansion joint, especially the expansion elbow 4, after the expansion joints are welded into a whole, it is necessary to measure their dimensions again. Specifically, as mentioned above, measure the dimensions of the corrugated section 41 of the total length dimension of the expansion joint and compare it with the original data. If the difference between the current data and the original data exceeds the predetermined limit value, the expansion joint shall be removed and replaced with a new one. Since it has not been welded to the low-temperature pipe 1 and the deck 2 at this time, it is relatively convenient to remove it at this time.

[0040] After that, the expansion joint needs to be welded and installed on the low-temperature pipe 1 and the deck 2. During welding, the first liner plate 3 needs to be welded and connected to the low-temperature pipe 1, and the circular ring support 6 needs to be welded and connected to the deck 2. In this embodiment, first, the circular ring support 6 is welded to the deck 2. After the circular ring support 6 and the deck 2 are welded, the welding of the first liner plate 3 and the low-temperature pipe 1 is carried out, so as to avoid the gap between the circular ring support 6 and the deck 2 due to the welding error between the first liner plate 3 and the low-temperature pipe 1 after the first liner plate 3 and the low-temperature pipe 1 are welded, thus generating prestress. Then, the installation of other pipelines can be carried out, such as installing the low-temperature support on the low-temperature pipe 1 in place. After welding is completed, the temporary fixing rod 42 on the expansion elbow 4 needs to be cut off. During cutting, the cut is smoothed to avoid generating sharp parts. After cutting is completed, the total length dimension and the corrugated section 41 dimension of the expansion elbow 4 in the expansion joint are measured again and compared with the original data. If the difference between the current data and the original data exceeds the predetermined limit value, the expansion joint shall be removed and replaced with a new one.

[0041] That is to say, through three data measurements, it can be ensured that the material supply stage, the expansion joint assembly stage, and the installation stage on the ship all meet the process requirements. On the one hand, the unqualified rate is reduced by controlling the welding method and other processes. On the other hand, problems are detected as early as possible through multiple measurements to avoid discovering problems after all operations are completed, which will be more troublesome to replace.

[0042] It should be clear that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts belong to the scope of protection of the present invention.

Claims

1. A method for installing a cryogenic pipe through-cabin expansion joint, characterized in that: First, preparations are made for the installation of the cryogenic pipe on the deck, sufficient installation space is provided, and the cryogenic pipe is kept concentric with the penetration hole on the deck; the total length and the size of the corrugated section of the expansion bend in the expansion joint are measured and compared with the original data during design. If the difference between the data and the original data at this time exceeds the predetermined limit, a new expansion joint is replaced; then the various parts in the expansion joint are welded together, and the total length and the size of the corrugated section of the expansion bend in the expansion joint are measured again and compared with the original data. If the difference between the data and the original data at this time exceeds the predetermined limit, the expansion joint is removed and replaced with a new expansion joint; then the expansion joint is welded and fixed to the cryogenic pipe and the deck, and the total length and the size of the corrugated section of the expansion bend in the expansion joint are measured again and compared with the original data. If the difference between the data and the original data at this time exceeds the predetermined limit, the expansion joint is removed and replaced with a new expansion joint.

2. The installation method of the cryogenic pipe penetration expansion joint according to claim 1 is characterized in that: When the expansion joint is welded and fixed to the cryogenic pipe and the deck, the annular support and the second lining plate are first welded to the deck, and then the first lining plate is welded and fixed to the cryogenic pipe.

3. The installation method of the cryogenic pipe penetration expansion joint according to claim 1 or 2, characterized in that: After the expansion joint is welded and fixed to the cryogenic pipe and the deck, the temporary fixing rods on the expansion joint are cut, and the total length and corrugated section size of the expansion bend are measured after cutting the temporary fixing rods.

4. The installation method of the cryogenic pipe penetration expansion joint according to claim 3 is characterized in that: After cutting the temporary fixing rod, smooth the cut.

5. The installation method of the cryogenic pipe penetration expansion joint according to claim 1 or 2, characterized in that: The total length dimension is the length of the two ends of the expansion bend along the axial direction. After the various parts of the expansion joint are welded together, the total length dimension is equal to the distance between the relative plate surfaces of the first lining plate and the second lining plate.

6. The installation method of the cryogenic pipe penetration expansion joint according to claim 1 or 2, characterized in that: During the welding of the first lining plate and the second lining plate to the expansion bend respectively, the outer periphery of the expansion bend is axially divided into at least four sections. When the sections are welded in sequence, the starting point of the welding is at least 90 degrees away from the end point of the previous welding section.

7. The installation method of the cryogenic pipe penetration expansion joint according to claim 6 is characterized in that: During the welding process of the first lining plate and the second lining plate to the expansion bend respectively, a thermometer is used to measure the temperature between the welding layers and keep it below 150°C.

8. The method for installing a cryogenic pipe penetration expansion joint according to claim 6, characterized in that: During the welding process of the first lining plate and the expansion bend, the distance between the first lining plate and the expansion bend is maintained at no more than 3 mm.

9. The installation method of the cryogenic pipe penetration expansion joint according to claim 1 or 2, characterized in that: When welding the various parts in the expansion joint together, first weld the first lining plate and the expansion bend together, and then connect the welded first lining plate and the expansion bend to the second lining plate and the annular support sleeve on the cryogenic pipe, and weld and assemble them on the outer periphery of the cryogenic pipe.

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