Socket and spigot joint type multi-layer pipe with corrosion-resistant metal lining

Abstract

The utility model discloses a corrosion-resistant metal lining socket type multilayer pipe, which belongs to the technical field of pipes and comprises an inner pipe, a middle layer and an outer pipe which are sequentially sleeved from inside to outside, steps and / or grooves are arranged on the inner wall of a socket end, and the inner pipe, the middle layer and the outer pipe are adhered to form the pipe or compressed to form the pipe. The outer pipe comprises a socket end, a pipe body and a spigot end which are connected in sequence, the outer pipe is made of metal, the inner pipe is made of a corrosion-resistant material, each end of the pipe is provided with a sealing layer and a lining ring made of a corrosion-resistant metal material, and the length of each lining ring extending into the pipe is not less than 20mm. The anti-corrosion pipeline is good in anti-corrosion effect, and the water conveying efficiency of the pipeline is improved. The corrosion-resistant metal lining ring prevents each layer of material from being stripped; and the strength and the deformation resistance of the pipe are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of pipes, in particular to a socket-and-spigot type multi-layer pipe with a corrosion-resistant metal lining. Background Art

[0002] Composite pipes are widely used pipes, often used in liquid transportation pipe network systems. They are generally of a spigot-and-socket structure, including an outer metal pipe and an inner plastic pipe, that is, the plastic pipe is used as the inner lining, one end of the metal pipe is a spigot end, and the other end is a socket end. During installation, multiple composite pipes are connected in sequence, and the spigot end of a composite pipe is inserted into the socket end of the adjacent composite pipe. However, the thermal expansion coefficient of the plastic pipe lining is quite different from the expansion coefficient of the metal outer pipe. The inner and outer pipes will produce a certain amount of internal stress that separates from each other due to temperature changes, which will cause the lining to delaminate. In addition, liquids can easily penetrate from the pipe ends, causing the outer pipe to rust and contaminate the transported liquid, and causing the end faces of each layer to peel off and delaminate. The inner layer may even be washed away under long-term scouring.

[0003] For water supply pipes in normal use, they will be subjected to a large internal water supply pressure, which is a positive pressure, so the pipes must meet the specified strength requirements. Some existing standards (group standards and national standards) specify the nominal wall thickness under different pressure levels and different nominal diameters. Pipes that meet the standards can meet the strength requirements within the corresponding pressure level range. Therefore, the pipes produced by existing pipe manufacturers generally meet the corresponding standard requirements.

[0004] However, when a pipe network fails, for example, a pipe bursts in the pipe network, the water in the pipe network will spray out from the burst pipe, and the pressure in the pipe network will drop rapidly, and even form a negative pressure. In addition, the pipe will be subject to some external pressure. For example, a pipe buried in the soil will be subject to the gravity of the soil above it. Under the action of the above external pressure and internal negative pressure, the pipe will deform radially. If the deformation of the socket end is too large, the socket end will separate from the socket end connected to it, causing leakage at the connection between the socket end and the socket end, causing the inside of the water pipe to be contaminated. Therefore, it is necessary to ensure that the deformation of the socket end of the pipe in the above situation does not exceed a certain range. For the socket end, the existing standards do not give its wall thickness requirements, but it is generally necessary to ensure that its thickness is sufficient to meet the strength requirements.

[0005] The base pipe in this article refers to the pipe in the factory setting, that is, the base pipe has no reinforcement ring installed and no secondary processing such as composite process. The base pipe includes a socket end, a pipe body and a spigot end connected in sequence. The pipe body can be divided into two parts, namely the main body and the transition part. The transition part is used for the transition connection between the main body and the socket end, that is, the socket end, the transition part, the main body and the spigot end are connected in sequence. The inner wall surface of the pipe body is a cylindrical surface, that is, the inner diameter of the transition part is equal to the inner diameter of the main body. The main body is cylindrical, and the outer wall surface of the transition part is a conical surface. In other words, the thickness of the main body is basically uniform everywhere, and the thickness of the transition part gradually decreases along the direction from the socket end to the spigot end. The outer diameter of the pipe body refers to the outer diameter of the main body, and the thickness of the pipe body refers to the thickness of the main body. The outer diameter of the base pipe is the outer diameter of the pipe body. Utility Model Content

[0006] In view of the above problems existing in the prior art, the purpose of the utility model is to provide a multi-layer socket-and-spigot pipe with a corrosion-resistant metal lining, which has good anti-corrosion effect, improves the flatness of the inner surface of the pipe, has a small lining thickness, improves the water delivery efficiency of the pipeline, and reduces the operating energy consumption. It can be used to transport high-temperature liquid media. A corrosion-resistant metal lining ring and a sealing layer are arranged at the end of the pipe to prevent the layers of material from peeling off and fix the inner pipe; at the spigot end, the length of the part of the lining ring extending into the pipe can be set to be not less than the length of the spigot end or the lining ring is turned outward to cover the outer wall of the spigot end at the same time, so that the spigot end and the metal lining ring form a composite spigot, which improves the strength and deformation resistance of one end of the pipe spigot; at the socket end, the lining ring can extend to partially cover or completely cover the inner wall of the socket end, so that the socket end and the metal lining ring form a composite socket, which improves the strength of one end of the pipe socket.

[0007] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0008] A multi-layer socket-and-spigot pipe with a corrosion-resistant metal lining comprises an inner pipe, an intermediate layer and an outer pipe which are sequentially sleeved from the inside to the outside, the inner wall of the socket end is provided with steps and / or grooves, the inner pipe, the intermediate layer and the outer pipe are bonded to form the pipe or compressed to form the pipe, the outer pipe comprises a socket end, a pipe body and a spigot end which are sequentially connected, the outer pipe is made of metal, the inner pipe is made of a corrosion-resistant material, each end of the pipe is provided with a sealing layer and a liner ring made of a corrosion-resistant metal material, the liner ring at one end of the socket end covers one end of the inner wall of the inner pipe, one end face of the inner pipe, one end face of the intermediate layer and the end face of the pipe body, the liner ring at one end of the spigot end covers the inner wall of the other end of the inner pipe, the end face of the other end of the inner pipe, the end face of the other end of the intermediate layer and the end face of the spigot end, and the length of each liner ring extending into the pipe is not less than 20 mm.

[0009] As a further improvement of the above technical solution:

[0010] The material of the middle layer is hot melt adhesive, plastic or rubber, and the material of the sealing layer is rubber or hot melt adhesive.

[0011] The liner ring at one end of the bell end is further extended to completely or partially cover the inner wall of the bell end.

[0012] When the liner ring at one end of the socket end extends to not completely cover the inner wall of the socket end, the liner ring covers the inner wall of the socket end between the sealing ring and the pipe body. When two adjacent pipes are connected, the socket end of one pipe is inserted into the socket end of the adjacent pipe and is sealed by the sealing ring located between the socket end and the socket end.

[0013] For the same pipe, along the direction from the socket end to the spigot end, the inner wall of the socket end includes the first step, the second step, the third step, the fourth step, and the fifth step arranged in sequence, and one end of the inner wall of the pipe body is the sixth step. The corresponding inner diameters are: D2, D1, (D3-2F), D3, D4, (D0-2S), D0 is the base pipe outer diameter of the pipe, S is the thickness of the pipe body, F≥0, and the sealing ring is installed at the third step.

[0014] The length of the portion of the liner ring at one end of the spigot extending into the interior of the pipe is not less than the length of the spigot end.

[0015] The lining ring at one end of the socket end is turned outward to cover the outer wall of the socket end.

[0016] At the socket end, the end face of the inner tube, the end face of the middle layer and the end face of the pipe body are all flush; at the spigot end, the end face of the inner tube, the end face of the middle layer and the end face of the spigot end are all flush.

[0017] At the socket end, the sealing layer covers the end face of the pipe body, the end face of the middle layer, the end face of the inner pipe and the inner wall of one end of the inner pipe; at the spigot end, the sealing layer covers the end face of the spigot end, the end face of the middle layer, the end face of the inner pipe and the inner wall of the other end of the inner pipe; the liner ring presses the sealing layer tightly; when in use, the liner ring at one end of the spigot end and the sealing layer form a full seal with the end face of the spigot end, and the liner ring at one end of the socket end and the sealing layer form a full seal with the end face of the pipe body.

[0018] The sealing layer includes a sealing layer press edge and a sealing layer flange, the sealing layer press edge is cylindrical, the sealing layer flange is annular, the lining ring includes a lining ring press edge and a lining ring flange, the lining ring press edge and the lining ring flange are a whole, the lining ring press edge is cylindrical, the lining ring press edge presses the sealing layer press edge, the lining ring flange presses the sealing layer flange, and the length of the lining ring press edge is not less than 20mm.

[0019] The beneficial effects of the utility model are:

[0020] (1) The inner tube made of corrosion-resistant metal material is used as the inner lining to completely isolate the outer tube from the liquid flowing in the tube, effectively preventing the outer tube from rusting, playing a good anti-corrosion role, increasing the service life of the tube, avoiding the rust of the outer tube from polluting the water quality, and improving the liquid transportation performance.

[0021] (2) Compared with plastic pipe linings, the inner pipe made of corrosion-resistant metal material as the inner lining eliminates the inner surface wrinkles and uneven defects caused by the melting of the inner lining plastic during compounding, improves the flatness of the inner surface of the pipe, and has a smaller lining thickness, which improves the water delivery efficiency of the pipeline and reduces operating energy consumption.

[0022] (3) The inner pipe made of corrosion-resistant metal material is used as the inner lining. Compared with the plastic pipe lining, the pipe can be used to transport high-temperature liquid media.

[0023] (4) The middle layer is made of insulating hot melt adhesive, plastic or rubber, which completely separates the inner tube from the outer tube to prevent the outer tube from contacting the inner tube and causing electrochemical corrosion to the inner tube. At the same time, it eliminates the uneven glue layer caused by the flow of ordinary liquid glue in the middle layer, and the electrochemical corrosion caused by the direct contact between the inner lining corrosion-resistant metal and the outer metal tube without bonding. It also overcomes the problems of easy aging and poor insulation of ordinary glue.

[0024] (5) When the middle layer is hot melt adhesive, the hot melt adhesive will bond the inner and outer layers together to prevent the inner lining from being delaminated due to negative pressure in the pipeline. When the middle layer is rubber, the elasticity of the rubber will cause the metal outer tube and the corrosion-resistant metal inner tube to form a mutual elastic force, which has good sealing performance for the inner wall of the metal tube and can prevent the liquid from contacting the inner wall of the metal outer tube and causing corrosion of the tube wall.

[0025] (6) A corrosion-resistant metal liner ring and a rubber sealing layer are provided at the end of the pipe to prevent the bonding surface ends between the layers of materials from contacting water and peeling off due to the tension of water, thereby preventing the inner wall of the metal outer pipe from rusting and peeling off and causing water pollution; the liner ring and the sealing layer fix the inner pipe, and when the seal fails and the inner liner is completely delaminated, the inner liner can still be protected from being washed away by the scouring of water flow; the provision of the liner ring and the sealing layer enhances the ring stiffness of the pipe end, the socket is not easily deformed, and the installation of the pipe is facilitated, and the uniform sealing effect of the sealing layer and the sealing ring at the connection between the two pipes is improved, thereby reducing pipeline leakage. The sealing layer is made of rubber or hot melt adhesive, which improves the sealing performance of the pipe end face. When the sealing layer is made of hot melt adhesive, the sealing layer bonds the liner ring and the inner pipe together, further improving the installation stability of the liner ring.

[0026] (7) At the socket end, the length of the portion of the liner ring extending into the pipe can be set to be no less than the length of the socket end, or the liner ring can be turned outward to cover the outer wall of the socket end, so that the socket end and the metal liner ring form a composite socket, which improves the strength and deformation resistance of the socket end of the pipe; at the socket end, the liner ring can be extended to partially cover or completely cover the inner wall of the socket end, so that the socket end and the metal liner ring form a composite socket, which improves the strength of the socket end of the pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the pipe described in Example 1 of the utility model.

[0028] Figure 2 yes Figure 1 An enlarged schematic diagram of point A.

[0029] Figure 3 This is a schematic diagram of connecting two adjacent pipes in Example 1 of the utility model.

[0030] Figure 4 It is a schematic diagram of the structure of the pipe in the second embodiment of the present utility model.

[0031] Figure 5 It is a schematic diagram of the structure of the pipe in the third embodiment of the present invention.

[0032] Figure 6 It is a schematic structural diagram of the fourth embodiment of the utility model in which the inner wall of the socket end of the pipe is not covered by a liner ring.

[0033] Figure 7 It is a structural schematic diagram of the fourth embodiment of the utility model in which the inner wall of the socket end of the pipe is not completely covered by the liner ring and the socket end has no intermediate layer.

[0034] Figure 8 It is a structural schematic diagram of the fourth embodiment of the present utility model in which the inner wall of the socket end of the pipe is completely covered by a liner ring and the socket end has no intermediate layer.

[0035] Fig. 9 It is a schematic structural diagram of the fifth embodiment of the present invention in which the inner wall of the socket end of the pipe is not covered by a liner ring.

[0036] Fig.10 It is a structural schematic diagram of the fifth embodiment of the present utility model in which the inner wall of the socket end of the pipe is not completely covered by the liner ring and the socket end has no intermediate layer.

[0037] Fig.11 It is a structural schematic diagram of the fifth embodiment of the present utility model in which the inner wall of the socket end of the pipe is completely covered by a liner ring and the socket end has no intermediate layer. DETAILED DESCRIPTION

[0038] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0039] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" may include both "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0040] Embodiment 1

[0041] A multi-layered socket-and-spigot pipe with a corrosion-resistant metal lining, the pipe is mainly used for passing water and corrosive liquids. Figure 1 As shown, it includes an inner tube 2, a middle layer 3 and an outer tube 1 which are sequentially sleeved from the inside to the outside.

[0042] The outer tube 1 is made of metal, preferably ductile iron or carbon steel. The outer tube 1 includes a socket end 11, a pipe body 12 and a spigot end 13 connected in sequence along its axial direction. The three are integrally cast, or the pipe body 12 and the spigot end 13 are integrally formed, and the pipe body 12 and the socket end 11 are welded. The spigot end 13 is cylindrical, and the spigot end 13 is chamfered along the circumferential direction. The inner diameter, outer diameter and thickness of the spigot end 13 can be equal to or unequal to the inner diameter, outer diameter and thickness of the pipe body 12, respectively.

[0043] The inner tube 2 is made of a metal material with corrosion resistance, including but not limited to stainless steel and titanium, preferably stainless steel, and the inner tube 2 is cylindrical.

[0044] The material of the middle layer 3 is non-metal, preferably hot melt adhesive, plastic or rubber. When the material of the middle layer 3 is hot melt adhesive, the hot melt adhesive has adhesive properties, and the inner tube 2 and the outer tube 1 are bonded together through the middle layer 3; when the material of the middle layer 3 is plastic or rubber, the plastic or rubber does not have adhesive properties, and the inner tube 2 presses the middle layer 3 against the inner wall of the outer tube 1.

[0045] The length of the inner tube 2 and the length of the middle layer 3 are equal, and are equal to the sum of the lengths of the pipe body 12 and the socket end 13. At the socket end 11, the ends of the inner tube 2, the middle layer 3 and the pipe body 12 are flush; at the socket end 13, the ends of the inner tube 2, the middle layer 3 and the socket end 13 are flush.

[0046] The thickness of the intermediate layer 3 is not less than 0.2 mm, and the thickness of the inner tube 2 is not less than 0.1 mm.

[0047] The main function of the inner tube 2 is corrosion protection, so its thickness should not be too large. A large number of welding tests have shown that under the conditions of fiber laser welding, a stainless steel plate with a minimum wall thickness of 0.1 mm can obtain a weld with high welding strength and small deformation. Taking into account the complexity of the welding process equipment, the investment cost, and the fact that the middle layer 3 shrinks at low temperatures due to its large thermal expansion coefficient, and generates internal stress that separates it from the outer tube 1, it is necessary to give full play to the supporting role of the inner tube 2 on the middle layer 3 to offset the internal stress of the outer tube 1 and the middle layer 3. The preferred thickness of the inner tube 2 is 0.1 mm-2 mm.

[0048] When the material of the middle layer 3 is hot melt adhesive, it acts as an adhesive layer. When the inner wall of the outer tube 1 is rough during compounding, the middle layer is heated and melted to fill the pits on the inner wall of the outer tube 1. If the thickness of the middle layer 3 is too small, poor adhesion is likely to occur in areas with large local roughness. At the same time, the middle layer 3 also acts as an insulating layer, and a certain thickness is required to produce an insulating effect between the outer tube 1 and the inner tube 2. The electric spark test and the peel strength test show that when the thickness of the middle layer 3 reaches 0.2mm or more, good peel strength and insulation performance can be stably obtained. The preferred thickness is 0.2mm-2mm.

[0049] Compared with the thickness of the inner lining stainless steel required by the standard "Inner lining stainless steel composite steel pipe (CJ / T 192-2017)", when the middle layer 3 uses hot melt adhesive, the inner lining stainless steel thickness is thinner and the cost is lower. When the inner diameter of the outer pipe 1 is the same, the inner diameter of the pipe is larger and the transportation efficiency is higher.

[0050] The conclusions of the lining peel strength test (this test uses an outer tube with an inner diameter of 100-300mm and an inner lining stainless steel thickness of 0.1mm-0.3mm) are as follows:

[0051] When the rust removal grade of the inner wall surface of the metal outer tube 1 reaches Sa2.5, the surface roughness is Ra12.5~Ra25, and the thickness of the intermediate layer 3 is not less than 0.2mm, the peel strength between the hot melt adhesive and the outer tube can stably reach more than 70N / cm; the peel strength between the hot melt adhesive and the inner lining can stably reach more than 150N / cm;

[0052] When the rust removal grade of the inner wall surface of the metal outer tube 1 reaches Sa2.5, the surface roughness is Ra25~Ra50, and the thickness of the intermediate layer 3 is above 0.2mm, the peel strength between the hot melt adhesive and the outer tube can stably reach above 120N / cm; the peel strength between the hot melt adhesive and the inner lining can stably reach above 150N / cm;

[0053] When the rust removal level of the inner wall surface of the metal outer tube 1 reaches Sa2.5, the surface roughness is greater than Ra50, and the thickness of the intermediate layer 3 is above 0.2 mm, the peel strength between the hot melt adhesive and the outer tube can stably reach above 150 N / cm; the peel strength between the hot melt adhesive and the inner lining can stably reach above 150 N / cm.

[0054] The peel strength between the hot melt adhesive and the lining of this solution can reach 150N / cm, and the corresponding bonding strength is 15MPa, that is, the pipe of this solution can withstand a liquid lateral scouring force of 15MPa, which is much greater than the maximum liquid lateral scouring force in the existing pipe network system.

[0055] When the middle layer 3 is hot melt adhesive, the thickness of the middle layer 3 is preferably 0.2 mm to 0.5 mm. When the thickness of the middle layer 3 is greater than 0.5 mm, the peel strength remains substantially unchanged.

[0056] A lining ring 5 and a sealing layer 4 are provided at one end of the spigot end 13 of the pipe, and a lining ring 5 and a sealing layer 4 are also provided at one end of the socket end 11. The lining ring 5 is made of corrosion-resistant metal, preferably stainless steel, and the sealing layer 4 is made of rubber or hot-melt adhesive. The sealing layer 4 at the spigot end 13 is used to cover and compress the end face and inner wall of the spigot end 13 of the pipe, and the lining ring 5 is pressed on the sealing layer 4. The sealing layer 4 at the socket end 11 is used to cover and compress the end face and inner wall of the pipe body 12 of the pipe near the socket end 11, and the lining ring 5 is pressed on the sealing layer 4.

[0057] like Figure 1 and 2 As shown, the sealing layer 4 includes a sealing layer edge 41 and a sealing layer flange 42, which are connected as one piece. The sealing layer edge 41 can be regarded as a thin cylindrical shape, and the sealing layer flange 42 is annular. The inner diameter of the sealing layer flange 42 is equal to the inner diameter of the sealing layer edge 41, and the outer diameter of the sealing layer flange 42 is greater than the outer diameter of the sealing layer edge 41. The sealing layer edge 41 and the sealing layer flange 42 share a common center line.

[0058] The structure of the liner ring 5 is similar to that of the sealing layer 4. The liner ring 5 includes an integrally connected liner ring pressure edge 51 and a liner ring flange 52. The liner ring pressure edge 51 can be regarded as a thin cylindrical shape, and the liner ring flange 52 is annular. The inner diameter of the liner ring flange 52 is equal to the inner diameter of the liner ring pressure edge 51, and the outer diameter of the liner ring flange 52 is greater than the outer diameter of the liner ring pressure edge 51. The liner ring pressure edge 51 and the liner ring flange 52 share a common center line.

[0059] In this embodiment, the length of the liner edge 51 at one end of the socket end 13 is not less than the length of the socket end 13. In other words, the length of the liner 5 at one end of the socket end 13 extending into the pipe is not less than the length of the socket end 13, so as to ensure that the liner 5 can cover the entire inner wall of the socket end 13 and improve the strength and deformation resistance of the entire socket end 13. At this time, the socket end 13 and the liner edge 51 form a composite socket. There is no special requirement for the length of the liner edge 51 at one end of the socket end 11, which can generally be no less than 20 mm.

[0060] Figure 2 In the illustrated view, the upper end surface of the sealing layer flange 42 does not extend beyond the upper end surface of the backing ring flange 52 .

[0061] At the socket end 11, the outer surface of the sealing layer edge 41 of the sealing layer 4 fits the inner surface of the inner tube 2, and the inner surface of the sealing layer edge 41 fits the outer surface of the liner ring 5. One side of the sealing layer flange 42 fits the end face of the inner tube 2, the end face of the intermediate layer 3 and the end face of the pipe body 12, and the other side of the sealing layer flange 42 fits the liner ring 5. The liner ring edge 51 of the liner ring 5 fits and compresses the sealing layer edge 41, and the liner ring flange 52 fits and compresses the sealing layer flange 42.

[0062] At the end of the socket end 13, the outer surface of the sealing layer edge 41 of the sealing layer 4 fits the inner surface of the inner tube 2, and the inner surface of the sealing layer edge 41 fits the outer surface of the liner ring 5. One side of the sealing layer flange 42 fits the end surface of the inner tube 2, the end surface of the intermediate layer 3 and the end surface of the socket end 13, and the other side of the sealing layer flange 42 fits the liner ring 5. The liner ring edge 51 of the liner ring 5 fits and compresses the sealing layer edge 41, and the liner ring flange 52 fits and compresses the sealing layer flange 42.

[0063] In this embodiment, the socket end 11 of the outer pipe is made of a single material and can be regarded as a single-layer socket. For the same pipe material, along the direction from the socket end 11 to the spigot end 13, the inner wall of the socket end 11 includes the first step 111, the second step 112, the third step 113, the fourth step 114, and the fifth step 115 arranged in sequence, and one end of the inner wall of the pipe body 12 is the sixth step, and the corresponding inner diameters are: D2, D1, (D3-2F), D3, D4, (D0-2S), wherein the inner diameters of the sixth step, the first step 111, the fifth step 115, the third step 113, the fourth step 114, and the second step 112 increase in sequence, that is: (D0-2S) < D2 < D4 < (D3-2F) < D3 < D1. D0 is the outer diameter of the base pipe of the pipe material, S is the thickness of the pipe body 12, and F≥0.

[0064] In this embodiment, the socket end 13 of the outer tube 1, the portion of the inner tube 2 covering the socket end 13, and the liner ring edge 51 form a composite socket of the pipe, and the composite socket has a three-layer structure.

[0065] For the socket end, because the middle layer 3 is made of non-metallic flexible materials such as hot melt adhesive, rubber, plastic, etc., and the sealing layer 4 is made of rubber or hot melt adhesive, it has basically no effect on the strength and deformation resistance of the socket end 13, so it does not belong to the category of composite sockets that can resist deformation.

[0066] Embodiment 2

[0067] Different from the first embodiment, in this embodiment, the liner ring 5 and / or the inner tube 2 at one end of the bell end 11 extends to cover the inner wall of the bell end 11 .

[0068] In this embodiment, the inner wall of the socket end 11 is covered by the liner ring 5 as an example. The liner ring 5 on the inner wall of the socket end 11 can be directly attached to the socket end 11, or an intermediate layer can be set between the socket end 11 and the liner ring 5, and the material of the intermediate layer is hot melt adhesive, plastic or rubber.

[0069] In this embodiment, the inner wall of the socket end 11 is not completely covered by the liner ring 5. Since the third step 113 is the installation location of the sealing ring Z, the coverage range of the liner ring 5 is generally from the fourth step 114 to the sixth step. Figure 4 shown.

[0070] In this embodiment, the socket end 11 and the portion of the liner ring 5 covering the inner wall of the socket end 11 form a composite socket of the pipe. Because the middle layer is made of hot melt adhesive or flexible non-metal such as plastic or rubber, it has little effect on the strength of the socket end 11, so it does not belong to the category of composite socket with strength.

[0071] Embodiment 3

[0072] Different from the second embodiment, in this embodiment, the inner wall of the entire base pipe socket end 11 is completely covered by the lining. Figure 5 shown.

[0073] In the case where the inner wall of the entire base pipe socket end 11 is completely covered by the lining, there is generally no third step 113, or in other words, the inner diameter of the third step 113 is equal to the inner diameter of the fourth step 114, and the two are combined into a large step, such as Figure 5 shown.

[0074] Embodiment 4

[0075] Different from the first embodiment, the second embodiment or the third embodiment, in this embodiment, the liner ring 5 at one end of the socket end 13 is extended and turned over to cover the outer wall of the socket end 13, and the length of the turned-over portion is not less than the length of the socket end 13, that is, the entire outer wall of the socket end 13 is covered by the liner ring 5. Figures 6-8 shown.

[0076] In this embodiment, the socket end 13 of the outer tube 1, the portion of the inner tube 2 covering the socket end 13, the liner ring edge 51, and the portion of the liner ring 5 covering the outer wall of the socket end 13 form a composite socket of the pipe, and the composite socket has a four-layer structure. The liner ring 5 portion located inside the pipe and the liner ring 5 portion covering the outer wall of the socket end 13 can also be regarded as a whole, which has a structure with two layers of the same material.

[0077] Embodiment 5

[0078] Different from the first embodiment, the second embodiment or the third embodiment, in this embodiment, the liner ring edge 51 at one end of the socket end 13 is only used to seal the end surface of the pipe, and is not used to form a composite socket. At this time, the length of the liner ring edge 51 at one end of the socket end 13 is generally less than the length of the socket end 13. Preferably, the length of the liner ring edge 51 at one end of the socket end 13 is not less than 20 mm. Figures 9-11 In this embodiment, the most vulnerable part of the socket end 13 of the pipe is equivalent to only the outer pipe 1 having strength and being able to resist deformation, which is a single-layer socket.

[0079] Finally, it is necessary to explain here that the above embodiments are only used to further illustrate the technical solution of the utility model in detail and cannot be understood as limiting the protection scope of the utility model. Some non-essential improvements and adjustments made by technicians in this field based on the above content of the utility model belong to the protection scope of the utility model.

Claims

1. A multi-layer bell-and-spigot pipe with a corrosion-resistant metal lining, characterized in that: The invention comprises an inner tube (2), an intermediate layer (3) and an outer tube (1) which are sleeved in sequence from the inside to the outside, the inner wall of the socket end (11) is provided with a step and / or a groove, the inner tube (2), the intermediate layer (3) and the outer tube (1) are bonded together to form the tube or pressed together to form the tube, the outer tube (1) comprises a socket end (11), a tube body (12) and a spigot end (13) which are connected in sequence, the outer tube (1) is made of metal, the inner tube (2) is made of a material having a corrosion-resistant function, and each end of the tube is provided with a sealing layer (4) and a lining ring (5) made of a corrosion-resistant metal material, the lining ring (5) at one end of the socket end (11) covers one end of the inner wall of the inner tube (2), one end face of the inner tube (2), one end face of the intermediate layer (3), and the end face of the tube body (12), and the lining ring (5) at one end of the socket end (13) covers the inner wall of the other end of the inner tube (2), the end face of the other end of the inner tube (2), the end face of the other end of the intermediate layer (3), and the end face of the socket end (13), and the length of each lining ring (5) extending into the interior of the pipe is not less than 20 mm.

2. The multilayer tube according to claim 1, characterized in that: The material of the middle layer (3) is hot melt adhesive, plastic or rubber, and the material of the sealing layer (4) is rubber or hot melt adhesive.

3. The multilayer tube according to claim 1, characterized in that: The lining ring (5) at one end of the bell end (11) further extends to completely or partially cover the inner wall of the bell end (11).

4. The multilayer tube according to claim 3, characterized in that: When the liner ring (5) at one end of the socket end (11) is extended to not completely cover the inner wall of the socket end (11), the liner ring (5) covers the inner wall of the socket end (11) between the sealing ring (Z) and the pipe body (12). When two adjacent pipes are connected, the spigot end (13) of one pipe is inserted into the socket end (11) of the adjacent pipe, and is sealed by the sealing ring (Z) located between the spigot end (13) and the socket end (11).

5. The multilayer tube according to claim 4, characterized in that: For the same pipe, along the direction from the socket end (11) to the spigot end (13), the inner wall of the socket end (11) includes a first step (111), a second step (112), a third step (113), a fourth step (114), and a fifth step (115) arranged in sequence, and one end of the inner wall of the pipe body (12) is a sixth step, and the corresponding inner diameters are: D2, D1, (D3-2F), D3, D4, (D0-2S), D0 is the base pipe outer diameter of the pipe, S is the thickness of the pipe body (12), F≥0, and the sealing ring (Z) is installed at the third step (113).

6. The multilayer pipe according to any one of claims 1 to 5, characterized in that: The length of the portion of the liner ring (5) at one end of the socket end (13) extending into the interior of the pipe is not less than the length of the socket end (13).

7. The multilayer tube according to claim 6, characterized in that: The liner ring (5) at one end of the socket end (13) is turned outward to cover the outer wall of the socket end (13).

8. The multilayer tube according to claim 1, characterized in that: At the socket end (11), the end face of the inner tube (2), the end face of the middle layer (3) and the end face of the tube body (12) are flush with each other, and at the spigot end (13), the end face of the inner tube (2), the end face of the middle layer (3) and the end face of the spigot end (13) are flush with each other.

9. The multilayer tube according to claim 1, characterized in that: At the socket end (11), the sealing layer (4) covers the end face of the pipe body (12), the end face of the intermediate layer (3), the end face of the inner pipe (2) and the inner wall of one end of the inner pipe (2); at the plug end (13), the sealing layer (4) covers the end face of the plug end (13), the end face of the intermediate layer (3), the end face of the inner pipe (2) and the inner wall of the other end of the inner pipe (2); the liner ring (5) presses the sealing layer (4) tightly; when in use, the liner ring (5) and the sealing layer (4) at one end of the plug end (13) form a full seal with the end face of the plug end (13), and the liner ring (5) and the sealing layer (4) at one end of the socket end (11) form a full seal with the end face of the pipe body (12).

10. The multilayer tube according to claim 9, characterized in that: The sealing layer (4) comprises a sealing layer pressing edge (41) and a sealing layer flange (42), the sealing layer pressing edge (41) is cylindrical, and the sealing layer flange (42) is annular; the lining ring (5) comprises a lining ring pressing edge (51) and a lining ring flange (52), the lining ring pressing edge (51) and the lining ring flange (52) are an integral part, the lining ring pressing edge (51) is cylindrical, the lining ring pressing edge (51) presses the sealing layer pressing edge (41), and the lining ring flange (52) presses the sealing layer flange (42), and the length of the lining ring pressing edge (51) is not less than 20 mm.

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