Large-diameter cast pipe hydrostatic test device

Abstract

This invention discloses a hydraulic pressure testing device for large-diameter cast iron pipes. A retaining wall is installed on both sides of the finishing line track. A baffle trolley is installed on the inner side of the retaining wall, and a baffle is fixed on the baffle trolley. A sealing gasket that mates with the socket of the cast iron pipe is installed on the sealing surface of the baffle. A central hole is machined on the baffle, concentric with the inner pipe, with a clearance fit. A pressure sealing ring is installed in a groove on the inner circumference of the central hole. A pad is installed on the retaining wall, and the pad is connected to the baffle by circumferentially distributed hydraulic cylinders. A moving trolley for fixing the inner pipe is installed on the outer side of the through-hole retaining wall, and V-wheels capable of vertical movement are installed on the outer wall. The bottom of the retaining wall is fixedly connected with a guide rail, and the top is fixedly connected with a tie rod, forming a frame structure. This invention significantly reduces the stress on the retaining wall during hydraulic pressure testing, reduces investment costs, improves hydraulic pressure efficiency, and has good versatility.

Description

Technical Field

[0001] This invention is applied to the field of cast iron pipe manufacturing, and relates to the quality inspection of large-diameter cast iron pipes, specifically a hydrostatic testing device for testing the strength of cast iron pipes. Background Technology

[0002] The national standard GB13295 for ductile iron pipes clearly stipulates that each pipe must undergo a hydrostatic test before leaving the factory. For large-diameter pipes (DN2200-3000), although the water pressure is relatively low (not less than 1.8 MPa), the thrust exerted on the test chamber's end walls by the large pipe diameter is significant, exceeding 1000 tons. Considering a safety factor, the design must withstand a thrust of nearly 2000 tons. Traditional design approaches place high demands on the stability of the hydrostatic testing device and the safety of the foundation. Furthermore, during hydrostatic testing of large-diameter pipes, the large pipe volume necessitates a large water injection volume, extending the ineffective testing time and resulting in low hydrostatic efficiency. Therefore, designing a low-cost, high-safety hydrostatic testing device that meets the requirements for large-diameter pipe hydrostatic testing is essential.

[0003] Numerous patents have been filed for ductile iron pipe hydraulic pressure testing devices, including CN212621939U, CN217980674U, CN101738344B, CN114279850A, and CN220120578U. CN212621939U discloses a hydraulic pressure testing machine for ductile iron pipes, suitable for small-diameter ductile iron pipes, solving the problem of high pressure on sealing rings and frequent replacement of spigot plugs. CN217980674U discloses a hydraulic pressure testing device for ductile iron pipes of different lengths, solving the hydraulic pressure problem of short pipes on standard-length production lines. CN101738344B discloses a hydraulic pressure testing machine for cast iron pipes and its tie rod pre-tightening installation method. The socket and spigot retaining walls are fixed, and a hydraulic cylinder pushes the socket end plug and spigot retaining wall together to seal the cast iron pipe. The tie rod relies on inner and outer locking nuts and inner and outer nuts for force. This hydraulic device structure cannot meet the hydraulic pressure requirements of large-diameter cast iron pipes unless a high-cost large-diameter hydraulic cylinder system and a high-strength threaded structure are used. CN114279850A discloses a hydraulic pressure testing device for ductile iron pipes, suitable for hydraulic pressure testing of cast iron pipes of different diameters, focusing on solving the problem of venting the inner cavity of the cast iron pipe during water injection. This patent, to achieve hydraulic pressure testing of pipes of different lengths, has sliding rails connected to the bottom ends of the blocking components at both ends of the cast iron pipe. Two sets of hydraulic cylinders push the pipe, and the reaction force of the cylinders acts on the support, which is fixedly connected to the upper end of the sliding rails. The biggest drawback of this patent application is that the support cannot withstand a unidirectional thrust of thousands of tons, making it unsuitable for hydraulic pressure testing of large-diameter cast iron pipes. CN220120578U discloses a pressure testing device for large-diameter pipelines, including a hydraulic testing machine, a fixed retaining wall, a socket sealing device, a spigot sealing device, an inner pipe, a telescopic mechanism, a movable retaining wall, and a support device. The inner pipe is concentrically fitted onto the cast iron pipe to reduce the pressure-bearing area of ​​the retaining walls at both ends, thereby solving the problem of the retaining walls bearing high thrust. However, this patent has the following problems and cannot be practically applied: 1) The socket and spigot sealing devices use spherical seals, and the tensile strength of the cast iron pipe is relatively low, not less than 420 MPa. The radial component of the spherical seal will cause damage to the cast iron pipe; 2) Although a support device is set at the bottom of the cast iron pipe, the inner pipe is not supported. The large-diameter inner pipe, 6 meters or 9 meters long, is suspended for a long time, resulting in poor safety; 3) The telescopic cylinder and the movable retaining wall cannot withstand the pressure of water pressure for a long time without special reinforcement of the retaining wall foundation and the use of expensive large-diameter hydraulic cylinders.

[0004] The applicant previously applied for a large-size ductile iron pipe hydraulic pressure device (application number 2024202858745), which uses a method of moving the cast pipe on a trolley and fitting the inner tube. From a usage perspective, this device has the following disadvantages: 1) The cast pipe needs to be loaded and unloaded from the finishing line, and then put back on the line after the hydraulic pressure test, which wastes time and reduces the production efficiency of the finishing line; 2) The sliding baffle, fixed wall and cylinder form a sealed pressure chamber, and the sliding baffle needs to slide within this pressure chamber. Due to the large size of this pressure chamber, the equipment manufacturing cost is high. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a large-diameter cast iron pipe hydrostatic testing device, in which the cast iron pipe is subjected to hydrostatic testing on the finishing line. The device has a simple structure, reduces the pressure on the retaining wall and foundation, reduces investment and operating costs, and improves hydrostatic efficiency.

[0006] The technical solution adopted in this invention is as follows: The large-diameter cast iron pipe hydrostatic testing device is installed on both sides of the finishing line track, including retaining walls, a baffle trolley, an inner pipe, and a moving trolley. Two retaining walls are fixed to the foundation outside the finishing line and connected by guide rails. A pad is installed on each retaining wall, and one retaining wall is a through-hole retaining wall. The baffle trolley is set on the guide rail inside the retaining walls, and a baffle is fixedly installed on the trolley. The inner surface of the baffle is a sealing surface, and a sealing gasket that mates with the socket of the cast iron pipe is installed on this sealing surface. The outer surface of the baffle is connected to the pad using circumferentially distributed hydraulic cylinders. A central hole is machined on the baffle, concentric with the inner pipe, and the two are clearance-fitted. A V-shaped or arc-shaped groove is machined on the inner circumferential surface of the central hole, and a pressure-filled sealing ring is installed in this groove. The through-hole retaining wall is machined with through holes, the size of which corresponds to the inner diameter of the largest specification cast pipe on the finishing line; a moving trolley is set on the outer side of the through-hole retaining wall, and an inner tube is installed on the moving trolley. The inner tube can be fitted inside the cast pipe and pass through the entire cast pipe; the outer wall of the through-hole retaining wall is equipped with V-wheels that can move up and down to support the inner tube.

[0007] Furthermore, the through-hole retaining wall is fixedly connected to the pad by a transition plate to adapt to changes in the specifications of the cast pipe.

[0008] Furthermore, the tops of the two retaining walls are fixedly connected by tie rods to form a frame retaining wall, which further reduces the stress on the foundation.

[0009] Furthermore, a V-wheel is fixedly installed on the baffle trolley. This V-wheel can be adjusted up and down to support and limit the inner tube, preventing the inner tube from forming a cantilever.

[0010] Furthermore, a water outlet pipe is provided inside the pressurized sealing ring, inserted between the inner tube and the cast pipe. This water outlet pipe is located at the upper part of the baffle, while the pressurized pipe of the pressurized sealing ring is located at the lower part of the baffle. The pressurized pipe and the water outlet pipe are located at the bottom of the pressurized sealing ring. This structure can further reduce the distance between the inner tube and the cast pipe, and further reduce the stress on the retaining wall.

[0011] Furthermore, a stop mechanism is designed in the middle of the finishing line track. This stop mechanism includes a stop rod and a hydraulic cylinder. The stop rod is a bent rod, with one end connected to the hydraulic cylinder and the bent position mounted on the rotating shaft. This stop mechanism serves as both a positioning device for the cast pipe and provides the power for the cast pipe to move along the finishing line after the hydrostatic test.

[0012] The water pressure test method using the above-mentioned water pressure testing device includes the following steps: 1) Preparation before pressure test: Prepare the pad, baffle, and inner tube according to the specifications of the cast pipe, and adjust the height of all V-wheels so that the center line of the inner tube and the center line of the cast pipe are horizontally aligned. 2) Positioning the cast pipe: The cast pipe rolls on the finishing line track to the pressure test station, and the stop lever positions the cast pipe so that the center line of the cast pipe is consistent with the center line of the inner tube. 3) Sealing the end face: The hydraulic cylinder extends, the baffle trolley moves, and the baffle makes sealing contact with the socket end face of the cast pipe. 4) Installing the inner tube: The moving trolley moves forward, and the inner tube, supported and guided by the V-wheels, is horizontally installed into the cast pipe until the inner tube passes through the center hole of the two baffles. 5) Sealing the center hole: Pressurized air or water is injected into the pressurization sealing ring, causing the pressurization sealing ring to expand and seal the gap between the center hole of the baffle and the inner tube. 6) Water pressure test: Water is injected into the cast pipe while air is vented. After the water is full, the pressure pump is started. 7) Depressurization and pipe delivery: After the water pressure test, the pressure is released, the hydraulic cylinder drives the baffle trolley to move backward, the moving trolley drives the inner pipe to be pulled out of the casting pipe, the stop rod pushes the casting pipe away, and the casting pipe rolls into the next station along the finishing line track.

[0013] Furthermore, in step 4), before the inner tube is installed at the inlet of the cast pipe, a plastic or rubber ball is placed inside the cast pipe to support the inner tube and prevent it from being cantilevered.

[0014] The beneficial effects of this invention are: the stress on the hydraulic pressure retaining wall of large-diameter cast iron pipes is greatly reduced, thus lowering the investment cost of the equipment. The cast iron pipes undergo hydraulic pressure testing on the finishing line, which is highly efficient and safe. The equipment has a simple structure and low operating costs. It is versatile and suitable for mass production. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the main structure of Embodiment 1, and also... Figure 2 Schematic diagram of the BB cross section; Figure 2 for Figure 1 Schematic diagram of AA section; Figure 3 for Figure 1A schematic diagram of the CC section; Figure 4 This is a schematic diagram of the deceleration mechanism; Figure 5 This is a schematic diagram of the main structure of Example 2; Figure 6 This is a schematic diagram of the pressurized sealing ring structure in Example 4; Among them: 1-Baffle wall, 2-Plate, 3-Hydraulic cylinder, 4-Baffle, 5-Cast pipe, 6-Inner pipe, 7-Transition plate, 8-Moving trolley, 9-V wheel, 10-Baffle trolley, 11-Guide rail, 12-Block lever, 13-Finishing line rail, 14-Sealing gasket, 15-Pressure sealing ring, 16-Pressure pipe, 17-Support rib, 18-Tie rod. Detailed Implementation

[0016] To reduce the stress on the retaining wall, the large diameter of the cast iron pipe can be considered large-diameter simply by using a water pressure test with an inner pipe inserted into the cast iron pipe. The term "inner side" refers to the side facing the finishing line, and "outer side" refers to the side away from the finishing line. Mechanisms or structures not described in detail in this specification are existing technologies, such as water injection and venting pipes, hydraulic systems, and V-wheel lifting mechanisms.

[0017] The principle of this invention is as follows: By inserting an inner tube inside the cast iron pipe, the cross-sectional area subjected to water pressure is reduced, thereby reducing the stress on the retaining wall, increasing the stability of the retaining wall foundation, and lowering the requirements for the foundation. The cast iron pipe undergoes a water pressure test on the finishing line, eliminating the need for hoisting or transportation, reducing the water filling volume, shortening the filling time, and improving water pressure efficiency. Example 1

[0018] The cast iron pipe hydrostatic testing device in this embodiment is as follows: Figure 1-3 As shown, the device is installed on both sides of the finishing line track 13, serving as a pressure testing station on the finishing line. The device includes a retaining wall 1, a baffle trolley 10, hydraulic cylinders 3, an inner tube 6, and a moving trolley 8. The retaining wall 1 is fixed to the foundation outside the finishing line. The bottoms of the two retaining walls are preferably connected by a guide rail 11 for the moving baffle trolley, forming a single unit to improve the stability of the retaining walls and reduce the design requirements of the foundation. Fasteners on the retaining wall 1 are used to install pads 2, and the pads 2 are connected to the baffle trolley 10 by circumferentially distributed hydraulic cylinders 3.

[0019] A baffle trolley 10 is positioned inside the retaining wall 1. A baffle 4 and a V-wheel 9 are fixedly mounted on the baffle trolley. The V-wheel 9 is located outside the baffle 4 and supports the inner pipe 6. A sealing gasket 14 is installed on the inner sealing surface of the baffle 4 where it mates with the casting pipe socket. This sealing gasket 14 is used to seal the end face of the casting pipe socket. To ensure the sealing performance during the hydrostatic test, the sealing gasket 14 should preferably be made of elastic rubber. A pad 2 is connected to the outside of the baffle 4 via a hydraulic cylinder 3. The extension and retraction of the hydraulic cylinder 3 can move the baffle trolley back and forth via the baffle 4, thus sealing or releasing the baffle 4 from the casting pipe socket.

[0020] A through hole is machined in one of the retaining walls 1, forming a through-hole retaining wall, through which the inner pipe 6 passes. A moving trolley 8 is positioned on the outside of the through-hole retaining wall, and the inner pipe 6 is fixed on the moving trolley 8. The length of the inner pipe 6 can extend through the entire cast pipe, and its outer diameter corresponds to the inner diameter of the cast pipe. The distance between the outer wall of the inner pipe and the inner wall of the cast pipe is minimized as much as possible while the inner pipe 6 moves back and forth without touching the inner wall of the cast pipe, thereby reducing the pressure-bearing area during the water pressure test, thus reducing the stress on the retaining wall and lowering the foundation requirements. To increase the strength of the inner pipe 6, evenly distributed longitudinal and circumferential ribs are welded to the inner wall of the inner pipe 6. The longitudinal ribs increase the bending strength of the inner pipe when it is cantilevered, ensuring the horizontality of the inner pipe when it is inserted and moved within the cast pipe. The circumferential ribs are used to improve the water pressure resistance. On the outer wall of the through-hole retaining wall, a V-wheel 9 that can be adjusted vertically is installed. This V-wheel supports the inner pipe, adapts to changes in the inner pipe's size, and assists in positioning the centerline of the inner pipe. The rotation of the V-wheel 9 reduces the frictional force during the movement of the inner pipe. The through-hole retaining wall uses a transition plate 7 to connect to the pad 2, accommodating adjustments for changes in cast pipe specifications. The through-hole size on the retaining wall corresponds to the inner diameter of the largest cast pipe on the finishing line, and the two are equal or only slightly different. When the cast pipe specification is large, the transition plate 7 can be omitted, and the pad 2 can be directly fixed to the retaining wall. If the cast pipe specification decreases and the inner tube size decreases, the transition plate 7 should be used to transition and connect to the retaining wall, ensuring that the thrust of the hydraulic cylinder acts on the circumferential surface of the cast pipe end. On the other retaining wall, since it does not pass through the inner tube, a through-hole does not need to be machined.

[0021] A central hole is machined on the baffle 4, through which the inner tube 6 passes. This central hole is concentric with the inner tube 6, and a gap is maintained between the inner surface of the central hole and the outer surface of the inner tube to facilitate the passage of the inner tube. A groove is machined on the inner circumferential surface of the central hole, and a pressure sealing ring 15 is installed in the groove. To increase the contact area between the pressure sealing ring 15 and the inner tube, the groove should preferably be a V-shaped groove or an arc-shaped groove with a large opening. The pressure sealing ring 15 is connected to the pressure tube 16 on the outside. When the pressure sealing ring 15 is pressurized, it can seal the gap between the central hole and the outer circumferential surface of the inner tube. When the pressure sealing ring 15 is depressurized, it enters the groove, and the inner tube 6 can pass smoothly through the central hole. To ensure that the pressure sealing ring retracts and enters the groove after depressurization, the pressure tube 16 should preferably be located at the bottom of the pressure sealing ring, i.e., near the outer diameter.

[0022] A deflector mechanism is designed in the middle of track 13 of the finishing line, as shown in the attached diagram. Figure 4 As shown, the system includes a deflector rod 12 and a hydraulic cylinder. The deflector rod is a bent rod, with one end connected to the hydraulic cylinder. The bent position is mounted on a rotating shaft. The deflector rod 12 is driven by the hydraulic cylinder to rotate at a small angle. When the hydraulic cylinder extends, the deflector rod 12 can block and position the cast pipe 5 on the finishing line track, ensuring that the center line of the cast pipe is aligned with that of the inner tube. After the hydrostatic test is completed, the hydraulic cylinder retracts, and the deflector rod rotates to move the cast pipe 5 away. The cast pipe 5 rolls along the finishing line track 13 into the next station. This deflector mechanism serves both as a positioning device for the cast pipe and as a driving force for the cast pipe to move along the finishing line after the hydrostatic test.

[0023] The pad 2, baffle 4, and inner tube 6 should be matched according to the specifications of the cast pipe. When the specifications of the cast pipe on the finishing line change, the pad 2, baffle 4, and inner tube 6 should be replaced accordingly. The V-wheel on the baffle trolley should be adjusted within a small range to correspond to the bottom arc surface of the inner tube. The baffles on the baffle trolley correspond to the sockets of the cast pipe. The hydraulic cylinder is fixedly connected to the pad 2 and baffle 4, and can be placed together on the baffle trolley for easy hoisting and overall replacement. After replacement, connect the quick-connect couplings of the hydraulic pipeline and tighten the pads on the retaining wall. The height of the finishing line track 13 is fixed. When the specifications of the cast pipe change, the position of its centerline also changes accordingly. The V-wheels on the outside of the baffle trolley and the lifting retaining wall can be replaced to make the centerlines of the cast pipe, the inner tube, and the center hole of the baffle consistent. However, it is necessary to carefully design the mounting holes on the transition plate or baffle to ensure that the hydraulic cylinders are evenly distributed around the centerline of the cast pipe.

[0024] In this embodiment, the following steps are taken: 1) Preparation before pressure testing: Prepare the pad 2, baffle 4, and inner tube 6 according to the specifications of the cast pipe. The baffle 4 is fixed on the baffle trolley, which is placed on the guide rail 11. The pad 2 is fixed on the retaining wall, and the inner tube 6 is fixed on the moving trolley 8. Adjust the height of all V-wheels so that the center line of the inner tube and the center line of the cast pipe are horizontally aligned. 2) Positioning the cast pipe: The cast pipe 5 on the finishing line track rolls to the pressure testing station. The stop lever 12 positions the cast pipe so that the center line of the cast pipe is aligned with the center line of the inner tube. 3) Sealing the end face: The hydraulic cylinder extends, the baffle trolley 10 moves, and the baffle 4 makes sealing contact with the socket end face of the cast pipe 5. 4) Installing the inner tube: The moving trolley 8 moves forward, and the inner tube 6, supported and guided by the V-wheels, is horizontally installed into the cast pipe 5 until the inner tube passes through the center hole of the two baffles. 5) Sealing the center hole. Pressurized air or water is injected into the pressurizing sealing ring 15 through the pressurizing pipe 16, causing the pressurizing sealing ring to expand and the gap between the center hole of the sealing baffle and the inner tube. This forms an annular sealed water injection chamber between the cast pipe, the inner tube, and the baffle. 6) Water pressure test. Water is injected into the water injection chamber through the water injection pipe, while air is released through the vent pipe. After the water is full, the pressure pump is started. After the pressure holding time, the outer surface of the cast pipe is observed for any leakage, and the pressure gauge pointer is observed to see if it drops. 7) Depressurization and pipe delivery. After the water pressure test, the water injection chamber is depressurized, the pressurizing sealing ring is depressurized, the hydraulic cylinder moves the baffle trolley backward, and the water in the cast pipe flows into the water tank. The moving trolley pulls the inner tube out of the cast pipe. After the inner tube is completely pulled out of the cast pipe, the stop lever pushes the cast pipe away, and the cast pipe rolls along the finishing line track to the next station, completing the pressure test of one cast pipe.

[0025] Notes: 1) The vent pipe should preferably be installed on the baffle that mates with the socket of the cast iron pipe, at the highest point of the water injection chamber, i.e., the top of the socket. The water injection pipe can be installed on the baffle that mates with the spigot of the cast iron pipe. 2) This embodiment can also be used for the hydrostatic test of short-length pipes, as long as the short-length pipes can be placed on the finishing line track. 3) Appendix Figure 1 The left and right sides are the sockets of the cast pipe, respectively. Alternatively, the cast pipe can be turned around, with the sockets placed on the right and left sides of the attached diagram, respectively. However, attention must be paid to the fit between the baffle and sealing gasket and the cast pipe sockets. 4) The longitudinal and circumferential ribs on the inner wall of the inner pipe can be... Figure 3 The supporting rib 17 shown is replaced. Example 2

[0026] The structure described in this embodiment is attached. Figure 5 Based on Example 1, the two retaining walls are fixedly connected at the top with tie rods 18. In this way, the two retaining walls 1, tie rods 18, and guide rails 11 form a frame structure. During water pressure testing, the force on the retaining walls is basically not transmitted to the foundation, reducing the requirements for the foundation. The addition of tie rods does not affect the rolling of the cast pipe on the finishing line track, nor does it affect the water pressure test operation. Example 3

[0027] To reduce the pressure of water on the baffle, the outer diameter of the inner pipe is increased as much as possible. However, for large-diameter cast iron pipes 9 meters or longer, the weight of the suspended inner pipe after it is inserted into the main pipe will inevitably generate a large bending moment and downward bending deformation. The inner pipe may also collide with the inner wall of the main pipe, damaging the cement lining. To avoid this, a solid plastic ball or hard rubber ball can be placed inside the main pipe before the inner pipe is inserted. The ball supports the inner pipe, and the inner pipe moves under the support of the rolling ball, ensuring smooth insertion. Plastic or rubber balls have good wear resistance and a certain degree of elasticity, and their rolling will not damage the cement lining of the main pipe. The diameter of the ball should ideally be equal to the distance between the outer wall of the inner pipe and the inner wall of the main pipe. Example 4

[0028] To reduce the space between the inner tube and the cast pipe, and further reduce the pressure on the retaining wall, the pressurized sealing ring in this embodiment is shown in the attached figure. Figure 6 As shown, the pressurizing pipe 16 of the pressurized sealing ring is combined with the water injection pipe for the hydraulic pressure test of the cast pipe. A water outlet pipe is added inside the pressurized sealing ring, extending into the space between the inner pipe and the cast pipe. The pressurizing pipe is located at the lower part of the baffle 4 of the pressurized sealing ring, and the water outlet pipe is located at the upper part of the baffle 4 (for magnified detail, the water outlet pipe and the pressurizing pipe are drawn together). Both the pressurizing pipe and the water outlet pipe should preferably be located at the bottom of the pressurized sealing ring. Water is first injected into the pressurized sealing ring to seal the inner pipe before being injected into the cast pipe. This structure can also eliminate the need for a pressurizing device, using a cast pipe hydraulic press to inject water into the pressurized sealing ring, and the water pressure is consistent with that in the injection chamber, ensuring the sealing effect of the pressurized sealing ring.

[0029] The large-diameter cast iron pipe hydraulic device of the present invention has the following advantages: 1. The stress on the retaining wall is significantly reduced. Taking a DN2500 cast iron pipe as an example (the following is an engineering calculation, not a design calculation, and does not consider a safety factor), with a water pressure test pressure of 1.8 MPa, without the inner pipe, the retaining wall bears a pressure of approximately 900 tons. Designed with an inner pipe outer diameter of 2300 mm, the ratio of the annular area of ​​the retaining wall bearing the water pressure to the diameter area of ​​the cast iron pipe is approximately 16%, and the pressure borne by the retaining wall is only about 145 tons, a significant reduction in stress. If the distance between the inner pipe and the inner wall of the cast iron pipe is further reduced, the stress on the retaining wall will be further reduced.

[0030] 2. This device requires minimal investment. The reduced pressure on the retaining wall lowers the investment in the hydraulic system of the hydraulic cylinder, and the reduced thickness and weight of the retaining wall and baffles eliminate the need for ultra-thick steel plates; thin steel structural plates can meet the requirements, thus reducing material costs. The device has a simple structure and low investment cost. In particular, the construction cost of the retaining wall foundation is significantly reduced, eliminating the need for deep excavation and the construction of ultra-large volume reinforced concrete foundations. Using a frame-type retaining wall, the foundation bears almost no pressure from the water pressure test, further reducing foundation construction costs. Using this invention's water pressure device can reduce the investment from nearly 4 million yuan for traditional large-diameter cast iron pipe water pressure devices to less than 1 million yuan.

[0031] 3. High efficiency in hydrostatic testing. When the specifications of the cast pipe are changed, the entire baffle trolley and inner pipe are hoisted and replaced, greatly reducing the time required for mold replacement. The cast pipe undergoes hydrostatic testing on the finishing line, eliminating the time spent on hoisting or transporting the cast pipe. The inner pipe is fitted inside the cast pipe, reducing the amount of water filled and drained during the hydrostatic test, significantly shortening the water injection and drainage time and saving production time at the hydrostatic station.

[0032] 4. Good versatility. This invention can be used for hydrostatic testing of small-diameter cast iron pipes without using a moving trolley and inner tube, and without machining a center hole on the baffle. As long as the length of the cast iron pipe can roll on the finishing line track, this device can be used for hydrostatic testing, and it can be applied to hydrostatic testing of non-standard length cast iron pipes. This invention is suitable for cast iron pipes with a diameter of DN2000 and above, and can also be used for cast iron pipes with a diameter of DN2000 and below. It can be used for both standard-length pipes and non-standard-length cast iron pipes.

[0033] 5. Low operating costs for hydrostatic testing. Reduced water consumption and smaller pool size lead to lower investment. Combined with reduced investment in retaining walls, foundations, and hydraulic stations, this results in lower fixed cost amortization. Increased efficiency and lower labor costs. Elimination of pipe hoisting or transport further reduces power costs. The simple structure, with virtually no moving parts besides the hydraulic cylinder, V-wheel, and trolley, allows for direct market procurement of these components, resulting in low maintenance and repair costs, easy replacement, and good production continuity.

[0034] 6. High production safety. In large-diameter cast pipe production workshops, the most dangerous operation is the hoisting or transportation of cast pipes. With this invention, the cast pipes are handled on the finishing line before and after water pressure testing, eliminating the safety hazards associated with hoisting or transportation. Furthermore, the reduced stress on the retaining wall significantly lowers the foundation resistance, thus improving the safety of the retaining wall foundation.

[0035] This invention solves the problem that technologies such as CN101738344B, CN114279850A, and CN220120578U are not suitable for large-diameter cast iron pipes. It meets the hydrostatic testing requirements for large-diameter cast iron pipes, with low stress on the retaining walls at both ends of the pipe and a high safety factor. Compared with the hydrostatic testing device for large-specification ductile iron pipes in application number 2024202858745, it not only reduces equipment investment and solves the problem of not needing to move the cast iron pipe on the finishing line, but also saves the operation of installing tie rods and crossbars for each hydrostatic test. It also makes replacing the inner pipe quick and convenient, improves the efficiency of hydrostatic testing, and is suitable for mass production.

Claims

1. A hydraulic pressure testing device for large-diameter cast iron pipes, characterized in that: Installed on both sides of the finishing line track, including retaining walls, baffle trolleys (10), inner tubes (6) and moving trolleys (8); the two retaining walls are fixed on the foundation outside the finishing line and are fixedly connected by guide rails; pads (2) are installed on the retaining walls, one of which is a through-hole retaining wall; The baffle trolley (10) is set on the guide rail inside the retaining wall. A baffle (4) is fixedly installed on the baffle trolley (10). The inner side of the baffle (4) is a sealing surface. A sealing gasket that matches the socket of the cast pipe is installed on the sealing surface. The outer side of the baffle (4) is connected to the pad (2) by a circumferentially distributed hydraulic cylinder. A central hole is machined on the baffle (4). The central hole is concentric with the inner pipe (6) and the two are fitted with a clearance. A V-shaped or arc-shaped groove is machined on the inner circumferential surface of the central hole. A pressurized sealing ring (15) is set in the groove. The through-hole retaining wall is machined with through holes, the size of which corresponds to the inner diameter of the largest specification cast pipe on the finishing line; a moving trolley (8) is provided on the outside of the through-hole retaining wall, and an inner tube (6) is installed on the moving trolley (8). The inner tube (6) can be fitted inside the cast pipe and pass through the entire cast pipe; a V-wheel (9) that can move up and down is provided on the outer wall of the through-hole retaining wall.

2. The hydraulic pressure testing device for large-diameter cast iron pipes according to claim 1, characterized in that: The through-hole retaining wall is fixedly connected to the pad (2) via the transition plate (7).

3. The hydraulic pressure testing device for large-diameter cast iron pipes according to claim 1, characterized in that: The tops of the two retaining walls are fixedly connected by tie rods (18).

4. The hydraulic pressure testing device for large-diameter cast iron pipes according to claim 1, characterized in that: V-wheels (9) are fixedly installed on the baffle trolley (10). The V-wheels (9) can be adjusted up and down to support and limit the inner tube (6).

5. The hydraulic pressure testing device for large-diameter cast iron pipes according to claim 1, characterized in that: The inner side of the pressurized sealing ring (15) is provided with a water outlet pipe inserted between the inner tube (6) and the cast pipe. The water outlet pipe is located at the upper part of the baffle (4), and the pressurized pipe of the pressurized sealing ring (15) is located at the lower part of the baffle (4). The pressurized pipe and the water outlet pipe are located at the bottom of the pressurized sealing ring.

6. The hydraulic pressure testing device for large-diameter cast iron pipes according to claim 1, characterized in that: The finishing line track is designed with a deflector mechanism in the middle. The deflector mechanism includes a deflector rod and a hydraulic cylinder. The deflector rod is a bent rod, with one end connected to the hydraulic cylinder and the bent position installed on the rotating shaft.

7. A water pressure testing method using the water pressure testing apparatus of claim 6, comprising the following steps: 1) Preparation before pressure test: According to the specifications of the cast pipe, prepare the pad (2), baffle (4) and inner pipe (6), and adjust the height of all V-wheels so that the center line of the inner pipe and the center line of the cast pipe are horizontal and corresponding; 2) Positioning the cast pipe: The cast pipe rolls on the finishing line track to the pressure testing station, and the stop rod positions the cast pipe so that the center line of the cast pipe is consistent with the center line of the inner pipe. 3) Sealing end face: The hydraulic cylinder extends, the baffle trolley (10) moves, and the baffle (4) makes sealing contact with the socket end face of the cast pipe; 4) Installing the inner tube: The moving trolley (8) moves forward, and the inner tube (6) is horizontally installed into the cast pipe under the support and guidance of the V wheel until the inner tube passes through the center hole of the two baffles; 5) Seal the center hole: Pressurized air or water is injected into the pressurized sealing ring (15) to make the pressurized sealing ring expand and seal the gap between the center hole of the baffle and the inner tube. 6) Water pressure test: Fill the cast iron pipe with water while venting air. After the pipe is full, start the pressure pump. 7) Depressurization and pipe delivery: After the water pressure test, the pressure is released, the hydraulic cylinder drives the baffle trolley to move backward, the moving trolley drives the inner pipe to be pulled out of the casting pipe, the stop rod pushes the casting pipe away, and the casting pipe rolls into the next station along the finishing line track.

8. The hydraulic pressure testing device for large-diameter cast iron pipes according to claim 7, characterized in that: In step 4), before the inner tube (6) is fitted into the inlet of the cast pipe, a plastic ball or a rubber ball is placed inside the cast pipe.

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