Lining stainless steel ductile iron cast pipe

Abstract

The utility model discloses a stainless steel lining ductile iron cast pipe. Stainless steel layers are laid on the inner wall of a socket from a socket convex ring to a socket retaining ring, the inner surface of a pipe body and the outer surface of a socket in a pressed mode. Bonding layers are arranged among the inner wall of the bellmouth, the outer surface of the spigot and the stainless steel layer, a cushion layer is arranged between the inner surface of the pipe body and the stainless steel layer, and the thickness of the cushion layer is not smaller than the crack height of the inner surface of the pipe body. After the bell and the spigot are connected, fluid conveyed in the pipeline only contacts with the stainless steel layer, the sealing ring and the cushion layer, so that the inner surface of the cast pipe is smooth and attractive.

Description

Technical Field

[0001] The utility model is applied to the field of water network pipelines and relates to a ductile iron pipe, in particular to a ductile iron pipe lined with a stainless steel layer. Background Art

[0002] Ductile iron pipes are the main pipelines for water network construction, with the advantages of fast construction speed and long service life. Although ductile iron has good air corrosion resistance, it still produces oxidation and electrochemical corrosion, so an anti-corrosion layer is applied to the inner and outer surfaces of the ductile iron pipe. The outer surface anti-corrosion layer is mainly used for anti-corrosion, usually using anti-corrosion paint, epoxy resin, etc., and the inner surface is usually coated with cement coating due to water quality requirements. There are the following problems with cement lining: 1) During coating production, the cast pipe is rotated to form a coating under the action of centrifugal force. Due to the ellipticity of the cast pipe, the rotating cast pipe will vibrate severely, make a lot of noise, and easily damage the equipment. 2) Centrifugal force causes uneven cement coating, with more slurry on the top of the coating and more sand on the bottom, and uneven coating strength, which affects the service life; 3) After the cement lining solidifies, it needs to be polished to ensure the smoothness of the inner surface, and cement polishing is a very inefficient and noisy job. Operators who have been in this position for a long time are more or less hard of hearing or deaf; 4) Usually, the cement coating is thicker, which increases the weight of the ductile iron pipe, and increases the construction cost and transportation cost.

[0003] CN215334973U discloses a cast iron composite pipe, in which a lining layer of PP-tube, PVC-U tube, stainless steel tube or copper tube is adhered to the surface of the cement lining layer to solve the problem of complicated manufacturing process of the existing cast iron pipe lining composite layer. CN201166196Y provides a ductile iron lined stainless steel composite pipe, in which the stainless steel pipe is bonded to the inner surface of the ductile iron pipe through an adhesive layer by cold expansion extrusion technology. CN206846105U discloses a ductile iron composite pipe lined with stainless steel, in which the stainless steel liner is attached to the inner wall of the ductile iron pipe by a hydraulic method, and the stainless steel liner is welded by spirally winding a steel strip, and the thickness of the stainless steel liner is 0.1mm to 3mm. The stainless steel liner is thin, which directly reveals the cracks on the inner surface of the cast iron pipe, and the surface is not beautiful. In addition, the above patents either do not have a lining in the socket, or do not involve this problem, or avoid this problem because the method is not suitable. Utility Model Content

[0004] The technical problem solved by the utility model is to provide a stainless steel lined ductile iron pipe, the inner wall of the pipe socket, the inner surface of the pipe body and the outer surface of the plug are all composited with a stainless steel layer, so as to ensure that after the pipeline is installed, the conveyed fluid only contacts the stainless steel or the sealing ring, and at the same time eliminate the cracks exposed in the stainless steel layer, and the surface is smooth and beautiful.

[0005] The technical solution adopted by the utility model is: the inner wall of the socket, the inner surface of the pipe body, and the outer surface of the socket of the stainless steel lined ductile iron cast pipe from the socket convex ring to the socket stop ring are all compounded with a stainless steel layer. The outer surface of the socket and the stainless steel layer are bonded with a bonding layer. The inner surface of the pipe body and the stainless steel layer are cushioned. The thickness of the cushion is not less than the height of the cracks on the inner surface of the pipe body, ensuring that the stainless steel layer is flat and beautiful.

[0006] Furthermore, there is an adhesive layer between the inner wall of the socket and the stainless steel layer. The stainless steel layer at this location is pressed and laid using an expansion ring device; the expansion ring device includes a support tube, an expansion ring, a fixed baffle and a movable baffle, etc. The fixed baffle is fixedly connected to the inner end of the support tube, the movable baffle is sleeved on the outer surface of the support tube, and an expansion ring is sleeved between the movable baffle and the fixed baffle.

[0007] Furthermore, the material of the stainless steel layer is not limited to stainless steel, and may also be replaced by a copper alloy layer, an aluminum alloy layer, a magnesium alloy layer, or a titanium alloy layer.

[0008] The beneficial effect of the utility model is that after the socket and spigot are connected, the fluid transported inside the pipeline only contacts the stainless steel layer and the sealing ring, and the cushion layer is used to make the inner surface of the cast pipe smooth and beautiful. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a partial schematic diagram of the axial cross section of the existing ductile iron pipe socket connection;

[0010] Figure 2 It is a partial schematic diagram of the axial cross section of the socket connection of the utility model;

[0011] Figure 3 It is a partial schematic diagram of the radial cross section of the pipe body of the utility model;

[0012] Figure 4 This is a schematic diagram of the stainless steel layer assembly of the socket deflection groove;

[0013] Figure 5 This is a schematic diagram of the stainless steel layer assembly of the socket sealing groove;

[0014] Among them: 1-socket, 2-socket, 3-stop block, 4-stop ring, 5-sealing ring, 6-cushion, 7-stainless steel layer, 8-adhesive layer, 9-tube body;

[0015] 11-deflection groove, 12-sealing groove, 13-retraction groove, 14-convex ring;

[0016] 21-support tube, 22-expansion ring, 23-fixed baffle, 24-movable baffle, 25-large baffle. DETAILED DESCRIPTION

[0017] The structure described in this utility model is mainly a multi-layer structure at both ends of the socket of the cast iron pipe. The following inside and outside are positioned in the direction of daily behavior habits, referring to the distance from the center of the inner cavity of the pipe body, such as the inner and outer surfaces of the cast pipe, attached Figure 1 The left side is outside and the right side is inside.

[0018] Attached Figure 1 It is a partial schematic diagram of the axial cross section of the existing ductile iron pipe socket connection. The two ends of the ductile iron pipe are the socket 1 and the spigot 2. When the ductile iron pipe is connected into a pipeline, the spigot 2 is inserted into the socket 1. The sealing ring 5 is installed in the socket sealing groove 12. The sealing ring 5 is fixed with the convex ring 14 in the sealing groove, and the sealing connection of the socket is realized by the elastic deformation of the sealing ring 5. The deflection groove 11 in the socket has a slope standard of 3°, that is, the connection between the spigot and the socket can be deflected at an angle of 3° to realize a flexible connection of the socket. In the T-type socket connection schematic diagram in the national standard, there is no backstop groove 13 and backstop ring 4. The backstop groove 13 and backstop ring 4 are structural designs added by the ductile iron pipe manufacturer to prevent the socket from detaching. A stop ring 4 is welded on the outer surface of the socket 2 of the ductile iron pipe at the appropriate position of the stop groove 13. When the socket is inserted into the socket, a stop block 3 is installed in the stop groove 13. The stop block 3 cooperates with the stop ring 4 to act on the stop groove 13 to prevent the socket from separating from the socket, thereby achieving an anti-separation effect.

[0019] Attached Figure 2 This is a schematic diagram of the socket connection of the stainless steel lined ductile iron pipe of the utility model. Figure 3 It is a schematic diagram of the cross section of the pipe body. The inner surface of the ductile iron pipe body 9 is lined with a stainless steel layer 7, and the thickness of the stainless steel layer 7 is preferably 0.1-1mm. A cushion layer 6 is set between the stainless steel layer 7 and the inner surface of the pipe body, and the thickness of the cushion layer 6 is not less than the height of the cracks on the inner surface of the pipe body. The functions of the cushion layer 6 are: 1) Eliminate the impact of the cracks on the inner surface of the pipe body on the appearance of the stainless steel layer 7. After the stainless steel layer 7 is bonded to the inner surface of the pipe body, the stainless steel layer 7 is smooth and beautiful. 2) It has a bonding effect and can firmly bond the stainless steel layer to the inner surface of the pipe body. 3) It should not have an adverse effect on water quality. 4) It has good deformation ability in the hot state and solidifies at room temperature. The cushion layer 6 is preferably made of asphalt, resin, plastic and other materials. When the pipe body is lined with a stainless steel layer, the heated cushion material is applied to the outer surface of the stainless steel pipe or the inner surface of the pipe body, and the stainless steel pipe is inserted into the pipe body. The inner surface of the stainless steel is pressurized, such as by liquid expansion, spinning, air pressure, etc., so that the stainless steel pipe undergoes plastic deformation and fits the inner surface of the pipe body. Under the action of pressure, the hot cushion material fills the space between the two layers to keep the inner surface of the stainless steel flat. It should be noted that the stainless steel pipe should be retained at the socket and spigot at both ends of the cast pipe. After the stainless steel lining of the pipe body is pressed, the stainless steel layer of the socket and spigot should be pressed.

[0020] At the socket of the cast pipe, the cushion layer 6 on the inner surface of the pipe body is replaced with an adhesive layer 8. First, because the inner surface of the socket is formed by the socket sand core, its inner surface is smooth and has no cracks, so no cushion layer is needed; second, the cushion layer is thick, which affects the installation size of the socket. Therefore, a thinner adhesive layer 8 is used to meet the requirement that the stainless steel layer is fixed on the inner surface of the socket after deformation. The thinner the adhesive layer, the better. After the stainless steel lamination of the pipe body is completed, the cushion material on the outer surface of the stainless steel pipe at the socket end is cleaned and the adhesive layer material is applied.

[0021] The stainless steel layer of the socket is pressed with an expansion ring device. The expansion ring device is as shown in the attached Figure 4 and attached Figure 5 As shown, it includes a support tube 21, an expansion ring 22, a fixed baffle 23, a movable baffle 24, etc. The fixed baffle 23 is fixedly connected to the inner end of the support tube 21, and the movable baffle 24 is sleeved on the outer surface of the support tube. The expansion ring 22 is sleeved between the movable baffle 24 and the fixed baffle 23. The expansion ring 22 is preferably made of a material with good elastic deformation such as rubber. Figure 4 The figure is a schematic diagram of the installation of the stainless steel layer in the deflection groove of the socket. The expansion ring device is inserted into the stainless steel pipe, the fixed baffle 23 is inserted into the junction of the socket and the pipe body, and the movable baffle 24 is moved to the junction of the deflection groove 11 and the sealing groove 12. A pressurized fluid, such as compressed air or high-pressure water, is filled into the expansion ring 22, so that the expansion ring 22 expands between the two baffles, and the stainless steel pipe gradually expands outward under the expansion pressure of the expansion ring. When the pressure is continued to be charged, the expansion of the expansion ring is mainly relieved from the gap between the movable baffle 24 and the stainless steel pipe. At this time, the increase in the outward expansion size of the stainless steel pipe is not obvious. A large baffle 25 is installed on the support tube 21, and the expansion ring is appropriately depressurized, and the large baffle is pushed to the junction of the deflection groove 11 and the sealing groove 12 to block the gap between the movable baffle and the stainless steel pipe. The expansion ring continues to be pressurized and deformed, so that the stainless steel pipe is plastically deformed and bonded together with the adhesive layer 8 in the deflection groove at the end of the socket. As shown in the attached figure Figure 5 After the stainless steel lamination of the deflection groove 11 is completed, the expansion ring is depressurized and the expansion ring device is withdrawn. Figure 5This is a schematic diagram of the stainless steel layer assembly of the socket sealing groove. After the stainless steel layer of the deflection groove is laid, the expansion ring device is replaced. The difference between this expansion ring device and the above expansion ring device lies in the size of the baffle. The fixed baffle 23 extends into the intersection of the deflection groove 11 and the sealing groove 12, and the movable baffle 24 moves to the intersection of the sealing groove 12 and the stop groove 13. The pressure fluid is rushed into the expansion ring 22, so that the expansion ring 22 expands between the two baffles. Under the expansion pressure of the expansion ring, the stainless steel pipe gradually expands outward and adheres to the inner surface of the sealing groove. It should be noted that during the expansion of the rubber ring and the deformation of the stainless steel pipe, friction is generated on the contact surface of the two. This friction causes tensile stress in the stainless steel pipe, which may cause tearing damage. Therefore, in order to reduce the friction, lubricating oil or wax is applied to the surface of the expansion ring before the expansion ring is stamped, and the low friction coefficient of the lubricating oil or wax is used to reduce the friction, thereby reducing the tensile stress of the stainless steel pipe and ensuring the smooth plastic deformation of the stainless steel pipe. It should be noted that 1) the stainless steel layer can be laid to the position of the convex ring 14, and the convex ring and the sealing ring cooperate to seal, and the water transported in the cast pipe will not contact materials other than stainless steel and rubber rings. 2) The method of pressing the stainless steel layer with the expansion ring eliminates the stress concentration caused by the sharp corners at the connection between the socket and the pipe body, which causes the stainless steel pipe to deform. The stainless steel pipe will not produce shear stress, so that the stainless steel layer can be lined in the socket. 3) Under normal circumstances, stainless steel uses austenitic stainless steel with good deformation ability, and the thickness of the stainless steel layer and the bonding layer is relatively thin, which does not affect the socket installation of the cast pipe. 4) The size of the sealing ring installation groove at the convex ring is small, and the deformation ability of the expansion ring may make the stainless steel layer unable to be completely bonded to the inner surface of the sealing groove, but as long as there is deformation of the stainless steel layer at the convex ring, the sealing ring can be accurately installed without affecting the use of the cast pipe pipeline. Or the stainless steel layer can be laid to the inside of the convex ring.

[0022] The stainless steel layer on the outer surface of the socket can be pressed by rolling. When the stainless steel tube is turned inside out, circumferential rolling is adopted. After being turned inside out, axial rolling is adopted. The stainless steel layer on the outer surface of the socket is pressed to the outside of the stop ring 4, so that the sealing of the sealing ring 5 can be achieved.

[0023] After the socket connection of the utility model, the water or other fluid transported inside the pipeline does not contact other materials such as the inner wall of the ductile iron pipe, the bonding layer, the cushion layer, etc. except the stainless steel layer and the sealing ring, thus ensuring the water quality of the fluid. The cushion layer eliminates the adverse effect of cracks on the stainless steel layer on the inner surface of the cast pipe, and the inner surface of the cast pipe is smooth and beautiful.

[0024] The material of the stainless steel layer of the lining of the utility model is not limited to stainless steel, and can also be replaced with other materials such as copper alloy, aluminum alloy, magnesium alloy, titanium alloy, etc. according to needs.

Claims

1. A stainless steel lined ductile iron pipe, characterized in that: The inner wall of the socket, the inner surface of the pipe body and the outer surface of the socket from the socket convex ring to the socket stop ring are all pressed with a stainless steel layer; a bonding layer is provided between the inner wall of the socket, the outer surface of the socket and the stainless steel layer; and a cushion layer is provided between the inner surface of the pipe body and the stainless steel layer.

2. The stainless steel lined ductile iron pipe according to claim 1, characterized in that: The stainless steel layer is pressed and laid using an expansion ring device; the expansion ring device comprises a support tube (21), an expansion ring (22), a fixed baffle (23), and a movable baffle (24); the fixed baffle (23) is fixedly connected to the inner end of the support tube (21), the movable baffle (24) is sleeved on the outer surface of the support tube, and the expansion ring (22) is sleeved between the movable baffle (24) and the fixed baffle (23).

3. The stainless steel lined ductile iron pipe according to claim 1, characterized in that: The thickness of the cushion layer is not less than the height of the cracks on the inner surface of the pipe body.

4. The stainless steel lined ductile iron pipe according to claim 1, characterized in that: The stainless steel layer is replaced by a copper alloy layer, an aluminum alloy layer, a magnesium alloy layer, or a titanium alloy layer.

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