Construction method for flaring type connection of steel-plastic composite pressure pipe

Abstract

The invention discloses a construction method for flaring type connection of a steel-plastic composite pressure pipe. The construction method comprises the steps of pipeline pretreatment, pipeline flaring machining, pipeline installation, pipeline pressure testing and pipeline flushing. According to the construction method, firstly, the steel-plastic composite pressure pipe is flared to form the horn mouth, fixed connection of the left steel-plastic composite pressure pipe section and the right steel-plastic composite pressure pipe section can be achieved only through a sealing connection structure in field installation, efficient connection of the steel-plastic composite pressure pipe can be achieved, operation can be achieved only through a special flaring machine and simple training of workers, operation is simple, and construction efficiency is high. And compared with a traditional welding connection technology, the construction efficiency is improved, the labor intensity of workers is reduced, and the technical requirement for the workers is low.

Description

Technical Field

[0001] This invention relates to the field of steel-plastic composite pressure pipe technology, and in particular to a construction method for flared connection of steel-plastic composite pressure pipe. Background Technology

[0002] With the development of the national economy and the improvement of people's living standards, people have higher and higher requirements for the function and quality of pipelines used in daily life and production activities. They not only require the pipeline network to be safe and reliable in operation and convenient and quick in installation and maintenance, but also require the pipeline to have excellent performance.

[0003] In building water supply and drainage and municipal water supply projects, pipelines, as the core components for transporting media, directly affect the stability of system operation due to their performance and connection quality. Traditional pipelines are mainly divided into two categories: steel pipes and plastic pipes. Although steel pipes have high strength and are easy to detect when buried, they suffer from drawbacks such as easy corrosion, susceptibility to contamination of the transported medium, heavy weight, and short service life. Plastic pipes, while corrosion-resistant and with smooth walls, have low strength, poor impact resistance, large thermal expansion, and are prone to deformation, making them unsuitable for high-pressure conditions. To address the shortcomings of existing steel and plastic pipes, manufacturers have designed a steel-plastic composite pressure pipe (PSP). This new type of pipe combines metal and plastic, employing a composite structure with a reinforced welded steel core and plastic layers on both the inner and outer surfaces. It overcomes the inherent drawbacks of steel pipes (easy corrosion, contamination, heavy weight, and short service life) and plastic pipes (low strength, large expansion, and easy deformation), while possessing the advantages of steel pipes (high strength, easy detection when buried) and plastic pipes (corrosion resistance and smooth walls).

[0004] The existing connection and installation processes for steel-plastic composite pressure pipes mainly employ welding, adhesive bonding, and clamp connections. These existing processes present the following problems during construction:

[0005] 1) Steel-plastic composite pressure pipes are connected by welding, which requires professional welders. The welding process is prone to fume pollution and the weld joints are prone to corrosion. The welding connection construction time is long, the construction period is difficult to control, the construction efficiency is low, and a variety of heavy tools are required, resulting in high labor intensity.

[0006] 2) Steel-plastic composite pressure pipes are connected by adhesive, which relies on adhesives. They are greatly affected by temperature and humidity, and the bonding strength decreases over time, making them prone to leakage.

[0007] 3) Steel-plastic composite pressure pipe clamps have poor pull-out resistance, are prone to loosening under high pressure conditions, and require complete disassembly for later maintenance, which has a significant impact on surrounding pipelines. Summary of the Invention

[0008] In view of this, in order to solve the technical problems existing in the prior art, the present invention provides a construction method that adopts a flared connection, is easy to install, has high pressure resistance, is easy to maintain, and can improve construction efficiency.

[0009] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0010] A construction method for flared connection of steel-plastic composite pressure pipe, the construction method comprising the following construction steps:

[0011] Step 1) Pipe pretreatment: Cut the steel-plastic composite pressure pipe at a right angle and clean the burrs at the pipe end; select an expansion head that matches the diameter of the steel-plastic composite pressure pipe and install it on the flaring machine so that the expansion head coincides with the axis of the steel-plastic composite pressure pipe.

[0012] Step 2) Pipe flaring process: Pass the steel-plastic composite pressure pipe through the pipe sleeve clamp structure of the flaring machine, and use the flaring machine expansion head on the flaring machine to flare the pipe end of the steel-plastic composite pressure pipe to form a bell mouth.

[0013] Step 3) Pipe installation: Place one flared steel-plastic composite pressure pipe as the left steel-plastic composite pressure pipe section on the support and hanger, and place another flared steel-plastic composite pressure pipe as the right steel-plastic composite pressure pipe section. Insert the bushing into the flared end of the left steel-plastic composite pressure pipe section, press the flared end of the right steel-plastic composite pressure pipe section against the bushing, and then use a sealing connection structure to fix the left and right steel-plastic composite pressure pipe sections in place.

[0014] Step 4) Pipeline pressure test: Perform a water pressure test on the steel-plastic composite pressure pipe system installed in Step 3). The test pressure is 1.5 times the working pressure and not less than 0.6 MPa.

[0015] Step 5) Pipe flushing: Flushing the steel-plastic composite pressure pipe system with a flushing water flow rate of 1.5-2 m / s.

[0016] As a further improvement to the above technical solution, the bushing mentioned in step 3) is an annular component, the shape of which is adapted to the inner wall of the bell mouth of the steel-plastic composite pressure pipe.

[0017] As a further improvement to the above technical solution, the sealing connection structure in step 3) includes a sealing ring, a left flared flange, a right flared flange, and a fastening assembly. The sealing ring is sleeved on the outer side of the end of the bushing. The left flared flange has a left pressure-bearing slope that matches the outer wall of the flared opening of the left steel-plastic composite pressure pipe section. The right flared flange has a right pressure-bearing slope that matches the outer wall of the flared opening of the right steel-plastic composite pressure pipe section. The left flared flange is placed on the left steel-plastic composite... The right flared flange is placed on the outer wall of the flared opening of the right steel-plastic composite pressure pipe section. The fastening assembly locks and fixes the left and right flared flanges on the left and right steel-plastic composite pressure pipe sections, so that the left pressure-bearing inclined surface of the left flared flange and the right pressure-bearing inclined surface of the right flared flange press against the outer wall of the flared opening of the left and right steel-plastic composite pressure pipe sections, respectively, thereby compressing the sealing ring to achieve the sealing of the left and right steel-plastic composite pressure pipe sections.

[0018] As a further improvement to the above technical solution, the fastening assembly includes a connecting bolt and two nuts. The connecting bolt passes through the left and right flared flanges and is tightened and locked in place by the two nuts. During the tightening process, the left and right flared flanges press the flared ends of the left and right steel-plastic composite pressure pipe sections respectively, so that the inner walls of the left and right steel-plastic composite pressure pipe sections tightly press the sealing ring to form two reliable oblique side seals.

[0019] As a further improvement to the above technical solution, the left flared flange is provided with a left through hole that mates with the connecting bolt, and the right flared flange is provided with a right through hole corresponding to the position of the left through hole. The connecting bolt passes through the left through hole of the left flared flange and the right through hole of the right flared flange and is then locked and fixed by double nuts.

[0020] As a further improvement to the above technical solution, the pipe processing in step 2) includes: cutting the plastic protrusion at the end of the flared steel-plastic composite pressure pipe so that the outer plastic at the end of the steel-plastic composite pressure pipe is on the same plane as the end face of the steel-plastic composite pressure pipe.

[0021] As a further improvement to the above technical solution, anti-slip pads are provided at the joint between the support and the flared steel-plastic composite pressure pipe in step 3).

[0022] As a further improvement to the above technical solution, the flushing of the steel-plastic composite pressure pipe system in step 5) adopts a segmented flushing method.

[0023] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0024] The construction method of this invention includes pipe pretreatment, pipe flaring, pipe installation, pipe pressure testing, and pipe flushing. The method first flares the steel-plastic composite pressure pipe to form a bell mouth. On-site installation only requires a sealing connection structure to achieve a fixed connection between the left and right steel-plastic composite pressure pipe sections, thus achieving efficient connection of the steel-plastic composite pressure pipe. Only a dedicated flaring machine is needed, and workers can operate it after simple training. The operation is simple, and the installation steps are few. Compared with traditional welding connection processes, it improves construction efficiency, reduces the labor intensity of workers, has low technical requirements for workers, significantly improves construction efficiency, reduces labor intensity, and uses a sealing connection structure for rigid connection, resulting in good sealing performance.

[0025] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, the following detailed description is provided in conjunction with preferred embodiments and accompanying drawings. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the construction method of the present invention;

[0027] Figure 2 This is a diagram showing the connection between the left and right steel-plastic composite pressure pipe sections of the present invention.

[0028] Figure 3 This is a schematic diagram of the flaring machine of the present invention;

[0029] Figure 4 This is a detailed enlarged schematic diagram of the expanding head in the flaring machine of the present invention.

[0030] In the diagram: 1. Steel-plastic composite pressure pipe; 11. Left steel-plastic composite pressure pipe section; 12. Right steel-plastic composite pressure pipe section; 13. Flared mouth; 2. Sealing connection structure; 21. Sealing ring; 22. Left flared flange; 23. Right flared flange; 24. Fastening assembly; 241. Connecting bolt; 242. Double nut; 3. Bushing; 4. Flaring machine; 41. Support base plate; 42. Expanding head; 43. Pipe clamp structure; 431. Pipe clamp; 432. Hydraulic cylinder; 433. Clamp support; 44. Pipe support frame; 441. Support plate; 442. Lifting cylinder. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the accompanying drawings, which form part of this specification. The principles of the invention are illustrated by means of embodiments, and other aspects, features, and advantages of the invention will become apparent from this detailed description. In the accompanying drawings, the same or similar parts in different figures are indicated by the same reference numerals.

[0032] like Figure 1As shown, Embodiment 1 of the present invention provides a construction method for flared connection of steel-plastic composite pressure pipe 1, the construction method including the following construction process:

[0033] Step 1) Pipe pretreatment: Cut the steel-plastic composite pressure pipe 1 at a right angle and clean the burrs at the pipe end; select a flaring machine 4 with a flaring head 42 that is compatible with the pipe diameter of the steel-plastic composite pressure pipe 1 and install it on the flaring machine 4 so that the flaring head 42 coincides with the axis of the steel-plastic composite pressure pipe 1.

[0034] Step 2) Pipe flaring: Pass the steel-plastic composite pressure pipe 1 through the pipe sleeve clamp structure 43 of the flaring machine 4, and use the flaring head 42 of the flaring machine 4 to flare the pipe end of the steel-plastic composite pressure pipe 1 to form a bell mouth 13; In specific implementation, before pipe processing, the flaring head 42 of the flaring machine 4 is lubricated.

[0035] Step 3) Pipe installation: Place one flared steel-plastic composite pressure pipe 1 as the left steel-plastic composite pressure pipe section 11 on the support and hanger, and place another flared steel-plastic composite pressure pipe 1 as the right steel-plastic composite pressure pipe section 12. Insert the bushing 3 into the flared end 13 of the left steel-plastic composite pressure pipe section 11, press the flared end 13 of the right steel-plastic composite pressure pipe section 12 against the bushing 3, and then use the sealing connection structure 2 to fix the left and right steel-plastic composite pressure pipe sections 12.

[0036] Step 4) Pipeline pressure test: Perform a water pressure test on the steel-plastic composite pressure pipe 1 system installed in Step 3). The test pressure should be 1.5 times the working pressure and not less than 0.6 MPa. Specifically, use a test pump to slowly increase the pressure for at least 10 minutes. After pressurizing to the test pressure, stabilize the pressure for 1 hour and observe for any leakage. After stabilizing the pressure for 1 hour, pressurize to the test pressure, and the pressure drop should not exceed 0.05 MPa within 15 minutes.

[0037] Step 5) Pipe flushing: Flushing the steel-plastic composite pressure pipe 1 system with a flushing water flow rate of 1.5-2m / s.

[0038] In the specific implementation of this invention, the selected flaring machine 4 is a medium-sized flaring machine 4 with an outer diameter of DN25-DN160.

[0039] The construction method of this invention first flares the steel-plastic composite pressure pipe 1 to form a bell mouth 13. On-site installation only requires a sealing connection structure 2 to achieve a fixed connection between the left and right steel-plastic composite pressure pipe sections 12, thus achieving efficient connection of the steel-plastic composite pressure pipe 1. Only a dedicated flaring machine 4 is needed, and workers can operate it after simple training. The operation is simple and the installation steps are few. Compared with traditional welding connection processes, it improves construction efficiency, reduces the labor intensity of workers, and has low technical requirements for workers, significantly improving construction efficiency and reducing labor intensity. The rigid connection using the sealing connection structure 2 offers advantages such as good sealing performance and simple and quick installation. The pipe processing uses a flaring machine 4 with a flaring head 42 adapted to the pipe diameter, ensuring that the flaring head 42 coincides with the axis of the steel-plastic composite pressure pipe 1, facilitating the flaring operation. The construction method of this invention is convenient, has low labor intensity, can shorten the construction period, and is easy to maintain. It is very suitable for building water supply and drainage and municipal water supply systems, and has significant economic and social benefits.

[0040] like Figure 2As shown, the bushing 3 mentioned in step 3) of the present invention is an annular component, the shape of which is adapted to the inner wall of the flared end 13 of the steel-plastic composite pressure pipe 1. The sealing connection structure 2 mentioned in step 3) includes a sealing ring 21, a left flared flange 22, a right flared flange 23, and a fastening assembly 24. The sealing ring 21 is sleeved on the outer side of the end of the bushing 3. The left flared flange 22 has a left pressure-bearing slope adapted to the outer wall of the flared end 13 of the left steel-plastic composite pressure pipe section 11. The right flared flange 23 has a right pressure-bearing slope adapted to the outer wall of the flared end 13 of the right steel-plastic composite pressure pipe section 12. The left flared flange 22 is placed on the outer wall of the flared end 13 of the left steel-plastic composite pressure pipe section 11. The right flared flange 23 is placed on the outer wall of the flared opening 13 of the right steel-plastic composite pressure pipe section 12. The fastening component 24 locks and fixes the left flared flange 22 and the right flared flange 23 on the left steel-plastic composite pressure pipe section 11 and the right steel-plastic composite pressure pipe section 12, so that the left pressure-bearing inclined surface of the left flared flange 22 and the right pressure-bearing inclined surface of the right flared flange 23 respectively press against the outer wall of the flared opening 13 of the left steel-plastic composite pressure pipe section 11 and the right steel-plastic composite pressure pipe section 12, thereby compressing the sealing ring 21 to achieve a seal between the left and right steel-plastic composite pressure pipe sections 12. The construction method of the present invention, by pre-flaring the steel-plastic composite pressure pipe 1, only requires the use of wrenches and other tools to tighten the fastening component 24. The operation is simple, the technical requirements for workers are low, the construction efficiency is greatly improved, and the labor intensity is reduced. In specific implementation, the sealing ring 21 of the present invention is preferably an O-ring, and the bushing 3 is made of malleable cast iron or ductile cast iron. The bushing 3 uses malleable cast iron or ductile cast iron as its main material, resulting in high mechanical rigidity. The overall pressure-bearing capacity of the steel-plastic composite pressure pipe 1 is significantly higher than that of traditional adhesive pipe fittings. At least one annular sealing groove is provided on the inner wall of the bushing 3. By setting the annular sealing groove, the sealing ring 21 can be easily embedded in the annular sealing groove of the bushing 3. Setting the area where the end face of the bushing 3 contacts the flared end 13 of the steel-plastic composite pressure pipe 1 is a conical slope or arc-shaped surface, which can better guide and accommodate the flared end 13, achieving uniform compression. The number of annular sealing grooves can be two or more, and multiple sealing rings 21 are embedded to further improve the sealing performance.

[0041] In this embodiment of the invention, the fastening assembly 24 includes a connecting bolt 241 and a double nut 242. The connecting bolt 241 passes through the left flared flange 22 and the right flared flange 23 and is tightened and locked in place by the double nut 242. During the tightening process, the left flared flange 22 and the right flared flange 23 respectively press the flared openings 13 of the left steel-plastic composite pressure pipe section 11 and the right steel-plastic composite pressure pipe section 12, so that the inner walls of the left steel-plastic composite pressure pipe section 11 and the right steel-plastic composite pressure pipe section 12 tightly press the sealing ring 21 to form two reliable oblique side seals. Mechanical tightening forces cause the left and right steel-plastic composite pressure pipe sections 11 and 12 to contract, forming a slanted seal with the sealing ring 21. This slanted seal connection provides a large contact area between the sealing ring 21 and the inner surface of the steel-plastic composite pressure pipe 1, effectively preventing leakage. Furthermore, when the medium pressure fluctuates, the sealing surface pressure increases synchronously with the medium pressure, resulting in more stable sealing performance. The connection method using connecting bolts 241 provides stable axial tensile force and strong pull-out resistance, meeting the needs of various working conditions such as buried and exposed installations. Each component of the steel-plastic composite pressure pipe 1 adopts a detachable structure. When future maintenance or pipe replacement is required, only the fastening component 24 needs to be disassembled to replace the steel-plastic composite pressure pipe 1 or the sealing ring 21, without damaging the structure of adjacent steel-plastic composite pressure pipes. This results in low maintenance costs and high efficiency.

[0042] In a specific implementation of this invention, the left flared flange 22 is provided with a left through hole that cooperates with the connecting bolt 241, and the right flared flange 23 is provided with a right through hole corresponding to the position of the left through hole. The connecting bolt 241 passes through the left through hole of the left flared flange 22 and the right through hole of the right flared flange 23 and is then locked and fixed by double nuts 242.

[0043] In other embodiments, the double nut 242 may be used instead of a screw nut.

[0044] In specific implementation, the pipe processing in step 2) includes: cutting the plastic protrusion at the end of the flared steel-plastic composite pressure pipe 1 so that the outer plastic at the end of the steel-plastic composite pressure pipe 1 is on the same plane as the end face of the steel-plastic composite pressure pipe 1.

[0045] In a specific implementation of the present invention, an anti-slip pad is provided at the joint between the support and the flared steel-plastic composite pressure pipe 1.

[0046] The flushing of the steel-plastic composite pressure pipe 1 system described in step 5) adopts a segmented flushing method. Combining segmented and layered pressure testing with standardized flushing, the pressure-bearing capacity of the steel-plastic composite pressure pipe 1 is ensured.

[0047] like Figures 3-4As shown, in a specific implementation, the flaring machine 4 of the present invention includes a supporting base plate 41 and a flaring head 42, a pipe clamping structure 43, and a pipe support frame 44 fixed on the supporting base plate 41. The pipe clamping structure 43 is disposed between the flaring head 42 and the pipe support frame 44. The pipe support frame 44 includes a supporting plate 441 and a lifting cylinder 442. The lifting cylinder 442 is located below the supporting plate 441, and the telescopic rod of the lifting cylinder 442 is connected to the supporting plate 441. The pipe clamping structure 43 includes two pipe clamps 431, two sets of hydraulic cylinders 432, and two sets of clamping supports 433. The two sets of clamping supports 433 are symmetrically fixed above the supporting base plate 41. The two sets of hydraulic cylinders 432 are respectively fixed to the upper ends of the two sets of clamping supports 433. The two pipe clamps 431 are arranged opposite to each other on the two sets of clamping supports 433. Each set of hydraulic cylinders 432 is connected to one pipe clamp 431.

[0048] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A construction method for flared connection of steel-plastic composite pressure pipe, characterized in that: The construction method includes the following construction process: Step 1) Pipe pretreatment: Cut the steel-plastic composite pressure pipe at a right angle and clean the burrs at the pipe end; select an expansion head that matches the diameter of the steel-plastic composite pressure pipe and install it on the flaring machine so that the expansion head coincides with the axis of the steel-plastic composite pressure pipe. Step 2) Pipe flaring process: Pass the steel-plastic composite pressure pipe through the pipe sleeve clamp structure of the flaring machine, and use the flaring machine expansion head on the flaring machine to flare the pipe end of the steel-plastic composite pressure pipe to form a bell mouth. Step 3) Pipe installation: Place one flared steel-plastic composite pressure pipe as the left steel-plastic composite pressure pipe section on the support and hanger, and place another flared steel-plastic composite pressure pipe as the right steel-plastic composite pressure pipe section. Insert the bushing into the flared end of the left steel-plastic composite pressure pipe section, press the flared end of the right steel-plastic composite pressure pipe section against the bushing, and then use a sealing connection structure to fix the left and right steel-plastic composite pressure pipe sections in place. Step 4) Pipeline pressure test: Perform a water pressure test on the steel-plastic composite pressure pipe system installed in Step 3). The test pressure is 1.5 times the working pressure and not less than 0.6 MPa. Step 5) Pipe flushing: Flushing the steel-plastic composite pressure pipe system with a flushing water flow rate of 1.5-2 m / s.

2. The construction method for flared connection of steel-plastic composite pressure pipe according to claim 1, characterized in that: The bushing mentioned in step 3) is an annular component, the shape of which is adapted to the inner wall of the bell mouth of the steel-plastic composite pressure pipe.

3. The construction method for flared connection of steel-plastic composite pressure pipe according to claim 1, characterized in that: The sealing connection structure described in step 3) includes a sealing ring, a left flared flange, a right flared flange, and a fastening assembly. The sealing ring is fitted onto the outer side of the end of the bushing. The left flared flange has a left pressure-bearing slope that matches the outer wall of the flared opening of the left steel-plastic composite pressure pipe section. The right flared flange has a right pressure-bearing slope that matches the outer wall of the flared opening of the right steel-plastic composite pressure pipe section. The left flared flange is placed on the outer wall of the flared opening of the left steel-plastic composite pressure pipe section, and the right flared flange is placed on the outer wall of the flared opening of the right steel-plastic composite pressure pipe section. The fastening assembly locks and fixes the left and right flared flanges on the left and right steel-plastic composite pressure pipe sections, so that the left pressure-bearing slope of the left flared flange and the right pressure-bearing slope of the right flared flange respectively press against the outer wall of the flared opening of the left and right steel-plastic composite pressure pipe sections, thereby compressing the sealing ring to achieve a seal between the left and right steel-plastic composite pressure pipe sections.

4. The construction method for flared connection of steel-plastic composite pressure pipe according to claim 3, characterized in that: The fastening assembly includes a connecting bolt and two nuts. The connecting bolt passes through the left and right flared flanges and is tightened and locked in place by the two nuts. During the tightening process, the left and right flared flanges press the flared ends of the left and right steel-plastic composite pressure pipe sections respectively, so that the inner walls of the left and right steel-plastic composite pressure pipe sections tightly press the sealing rings to form two reliable oblique side seals.

5. The construction method for flared connection of steel-plastic composite pressure pipe according to claim 4, characterized in that: The left flared flange has a left through hole that mates with the connecting bolt, and the right flared flange has a right through hole corresponding to the position of the left through hole. The connecting bolt passes through the left through hole of the left flared flange and the right through hole of the right flared flange and is then locked and fixed by double nuts.

6. The construction method for flared connection of steel-plastic composite pressure pipe according to claim 1, characterized in that: The pipe processing described in step 2) includes: cutting the plastic protrusion at the end of the flared steel-plastic composite pressure pipe so that the outer plastic at the end of the steel-plastic composite pressure pipe is on the same plane as the end face of the steel-plastic composite pressure pipe.

7. The construction method for flared connection of steel-plastic composite pressure pipe according to claim 1, characterized in that: In step 3), anti-slip pads are provided at the joint between the support and the flared steel-plastic composite pressure pipe.

8. The construction method for flared connection of steel-plastic composite pressure pipe according to claim 1, characterized in that: The flushing of the steel-plastic composite pressure pipe system described in step 5) adopts a segmented flushing method.

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