Onshore socket and spigot installation method for large diameter GRP seawater pipes

Abstract

The invention discloses a method for installing a large-diameter GRP seawater pipeline on land with a socket. The method comprises the following steps: firstly, prefabricating a GRP pipeline, adding a reinforcing rib at every 1m interval on the outer side of the GRP pipe, and processing a groove for placing an O-type rubber ring at the socket position; then manufacturing and positioning the GRP pipeline foundation; then installing the O-type rubber ring at the socket position, hoisting the GRP pipeline, and after the crane is hoisted into position, using the reinforcing rib as a support point, using hand chain hoists to pull both sides of the outer side of the pipeline at the same time, and finally the pipeline is socketed into position; after a water pressure test is performed, the pipeline is backfilled. The invention adopts a socket connection method, and the pipeline has a certain movable gap when subjected to an external force, and double "O"-type rubber rings are sealed to play a dual protective role for the pipeline seal; reinforced concrete piles, a cap and medium-coarse sand are used for the pipeline foundation, so that the pipeline can be guaranteed not to have a large displacement, and the sand filling between the pipeline and the cap can play a certain buffering role for the pipeline, so as to ensure the long-term stable operation of the pipeline.

Description

Technical Field

[0001] The invention belongs to the technical field of pipeline construction, and in particular relates to an onshore socket-and-spigot installation method for a large-diameter GRP seawater pipeline. Background Art

[0002] The LNG receiving station transmission system consists of a high-pressure pump, SCV, ORV, and metering skid. ORV (open-frame vaporizer) is the key equipment for gasification transmission. GRP seawater pipeline is an important part of the ORV system. It is mainly used for seawater transportation between the water intake and the open-frame vaporizer. After the normal temperature seawater enters the vaporizer, it exchanges heat with the low-temperature LNG, and the LNG is gasified and then transmitted. The material used for GRP seawater pipeline is glass fiber reinforced unsaturated polyester resin. This material has the advantages of excellent physical and mechanical properties, chemical corrosion resistance, long service life, and excellent hydraulic properties. It is widely used in LNG receiving stations. Traditional connection methods include manual paste and flange connection. Manual pasting is completed by alternately winding epoxy unsaturated resin, chopped strands of felt, woven fabric and some auxiliary materials. This connection method is complicated and cumbersome, and after one layer is completed during the hand pasting process, it is necessary to wait for solidification before the next layer can be constructed. The construction period is long, and after the pasting is completed, the pipeline is a whole. Any large disturbance or expansion will cause the pipeline to deform and break. When the flange connection encounters disturbance, it is also very easy to cause deformation and fracture of the pipeline, and the construction of large-diameter GRP pipelines is more complicated. Summary of the invention

[0003] To solve the above problems, the present invention discloses an onshore socket-and-spigot installation method for a large-diameter GRP seawater pipeline, which solves the difficulty of installing a large-diameter GRP pipeline, improves the quality of GRP pipeline installation, saves a lot of manpower and construction period, and effectively reduces construction costs.

[0004] To achieve the above object, the technical solution of the present invention is as follows:

[0005] A method for installing a large-diameter GRP seawater pipeline onshore with a spigot and socket joint, comprising the following steps:

[0006] (1) GRP pipe prefabrication:

[0007] GRP pipe is made of epoxy unsaturated resin, glass fiber mat and glass fiber cloth through winding molding. After the prefabrication of GRP pipe is completed, a reinforcing rib is added every 1m on the outside, and a groove for placing O-type rubber ring is processed at the plug position; waterproofing and ear picking are done well;

[0008] (2) GRP pipe foundation production:

[0009] The pipeline foundation is excavated to the designed elevation, the soil in the pile core is cleaned, the pile core cage is made, the cushion formwork is installed, the pile core and cushion concrete are poured, the cap steel bars are tied, and the cap formwork is installed. After the cap is poured, medium-coarse sand is backfilled on the cap, compacted with a small roller, and the sand filling in the cap is leveled;

[0010] (3) Locate the tee position of the GRP pipe;

[0011] (4) Pipeline hoisting and installation:

[0012] First, install an O-shaped rubber ring at the socket position, tie it to the GRP pipe with a sling to make the GRP pipe horizontal, hook the hand chain hoist to the sling, and after the crane is lifted into place, use the reinforcement as the support point, use the hand chain hoist to pull both sides of the pipe at the same time, and finally the pipe socket is in place, add a pad on the concrete foundation and fix both sides of the pipe with a spring bracket to improve the sealing of the socket;

[0013] (5) After the pipeline is installed in place, the socket is subjected to a water pressure test. If there is no pressure drop, the pressure test is qualified;

[0014] (6) Pipeline backfilling.

[0015] As an improvement of the present invention, there are two grooves at the socket position in step (1).

[0016] As an improvement of the present invention, during the GRP pipe foundation manufacturing process in step (2), a thrust pier is provided at the turning point of the GRP pipe.

[0017] As an improvement of the present invention, the thrust pier is composed of bottom plate steel bars, pipe annular bars, and top layer surface bars, and is cast outside.

[0018] As an improvement of the present invention, in step (3), while positioning the GRP pipe tee, each crossing and socket is positioned, and a protective sleeve is added at each crossing position. During installation, a hand winch is first used to shift the GRP pipe and pass the GRP pipe through the entire protective sleeve.

[0019] As an improvement of the present invention, the pressure of the water pressure test in step (5) is 1.2 MPa, and the pressure is maintained for ten minutes without any pressure drop, and the pressure test is considered qualified.

[0020] As an improvement of the present invention, when the pipeline is backfilled to the top of the pipe in step (6), the socket pressure test is performed again.

[0021] The beneficial effects of the present invention are:

[0022] (1) GRP pipes are prefabricated into fixed socket pipe sections using factory molds to ensure that the socket sizes of each pipe are consistent, ensuring installation accuracy and quality.

[0023] (2) Using double "O" rings for sealing can provide double protection. The socket connection has a certain amount of free clearance, which will not cause damage to the pipeline when it is subjected to external force. In addition, the double "O" rings can better prevent the pipeline from leaking when it is displaced.

[0024] (3) The pipeline foundation uses prefabricated reinforced concrete piles and reinforced concrete caps to ensure that the pipeline does not undergo large displacement. Filling the space between the concrete cap and the pipeline with medium-coarse sand can provide a certain buffering effect on the pipeline and ensure long-term stable operation of the pipeline.

[0025] (4) Prefabrication in the factory and on-site socket installation can reduce the investment in construction personnel, and the construction speed is faster, which can shorten the construction period and greatly reduce the construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention.

[0027] Figure 2 This is a schematic diagram of the GRP pipeline described in the present invention.

[0028] Figure 3 This is a schematic diagram of the installation of the present invention. Implementation

[0029] The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0030] Taking the XX liquefied natural gas (LNG) receiving station project as an example, the seawater pipeline uses DN2400mmGRP pipes, each pipe is 12m long, weighs about 6t, and is buried 5m deep. This area is close to the sea, the groundwater level is high, the soil water content is large, and most of it is spring soil. This kind of foundation pipeline is prone to irregular settlement. The traditional connection method is not suitable for installation under such working conditions, nor is it conducive to the long-term and stable operation of the pipeline.

[0031] The installation method includes the following steps:

[0032] 1. GRP pipe prefabrication

[0033] 1) GRP pipe is composed of epoxy unsaturated resin, glass fiber felt and glass fiber cloth, and is manufactured by winding molding. The principle is to use special winding equipment to impregnate continuous glass fiber and cloth with resin glue under controlled tension and predetermined linear conditions, and then continuously and evenly wind them on the core mold or lining, and then solidify them under certain temperature conditions.

[0034] 2) After the prefabrication of the round tube, add a reinforcing rib every 1m, such as Figure 2 As shown, a groove for placing the rubber ring is processed at the socket position, and the groove depth is strictly controlled to ensure the sealing of the rubber ring.

[0035] (3) Ensure waterproofing and ear picking.

[0036] 2. Pipeline foundation production

[0037] 1) Excavate the pipeline foundation to the designed elevation, clean the soil in the pile core, make the pile core cage, install the cushion formwork, pour the pile core and cushion concrete in time, and clean the surface water before pouring the concrete;

[0038] 2) After the cushion concrete is solidified, tie the cap steel bars to ensure that the steel bar specifications and spacing meet the design requirements, install the cap formwork, ensure that the steel bar protection layer meets the specification requirements, and the formwork reinforcement should be firm to prevent the formwork from bursting during the pouring process;

[0039] 3) Thrust piers are set at the turning points of the pipeline to prevent the pipeline from shifting due to water flow impact during operation. The thrust piers are composed of bottom plate steel bars, pipeline annular bars, and top layer steel bars. The steel bars are used to wrap the pipeline firmly.

[0040] 4) After the foundation is poured, fill it with medium-coarse sand and compact it with a small roller, which can act as a buffer when the pipeline is running.

[0041] 3. Pipeline marking and positioning

[0042] 1) Before installing the GRP pipe, the sand filling inside the pipe foundation cap must be leveled to ensure that the center elevation of the pipe is consistent after installation;

[0043] 2) First locate the tee position of the buried pipeline to ensure the accuracy of the tee position, and then locate the protective casing and the socket of each crossing to avoid the socket being inside the steel casing;

[0044] 3) When installing the pipeline, install it from the tee position to both sides. Position and re-measure each section of the pipeline. After the pipeline is hoisted in place, re-measure the elevation to ensure that the pipeline is level;

[0045] 4) Hoist the GRP pipe to the foundation location. For the position where the socket is higher, use a shovel to clean up the filling sand, and use sandbags to pad the pipe socket to prevent the pipe from sinking;

[0046] 5) For the pipeline in the passing casing, first hoist the protective casing into place, then place the GRP pipe on one end of the protective casing, and use a hand winch to shift it until the pipeline passes through the entire protective casing.

[0047] 4. Pipe socket installation

[0048] 1) Clean the double grooves at the GRP pipe socket end to prevent debris from affecting the sealing of the rubber ring;

[0049] 2) Apply butter to the groove and sealing ring to facilitate the sealing ring to be placed in the groove, and apply butter to the inside of the pipe socket to facilitate the insertion of the socket during pipe installation;

[0050] 3) Before installing the socket, measure the size of the pipe socket and the spigot. The error should not be greater than 10mm. If the gap is too large, the pipe will not be sealed tightly after installation, and there is a possibility of leakage during operation.

[0051] 4) According to the pipe socket data sheet, measure the socket size on the pipe socket and spigot and mark them, so that the socket installation will be more accurate;

[0052] 5) Install the socket pressure nozzle, which is used when checking the sealing of the socket. When installing the O-ring, install the inner groove first and then the outer groove;

[0053] 6) Tie the sling to the pipe, hook the hand chain hoist to the sling, lift the pipe to be installed with a crane, and use the hand chain hoist to pull both sides of the pipe at the same time to ensure that the dimensions of the socket on both sides are consistent, such as Figure 3 As shown;

[0054] 7) After the GRP pipe is in place, use a level to measure the pipe elevation to ensure that the center elevation of the pipe is consistent. Use a plumb line to check whether the pipe end is vertical. If not, lift the pipe and use sandbags to level it.

[0055] 8) Add pads to the concrete foundation and use spring brackets to fix both sides of the pipe to improve the sealing of the socket.

[0056] 5. After the GRP pipe is installed in place, the socket is subjected to a pressure test. The design pressure is 0.8MPa, the test pressure is 1.2MPa, and the pressure is maintained for ten minutes. If there is no pressure drop, the pressure test is qualified.

[0057] 6. Pipeline backfill

[0058] Manually fill and compact the sand between the pipe and the foundation;

[0059] It is strictly forbidden to bring stones into the backfill soil to prevent damage to the pipeline. Backfill should be done in layers, with each layer being 200mm. Both sides of the pipeline should be backfilled at the same time to prevent displacement of the pipeline caused by unilateral backfilling.

[0060] 3) When the pipeline is backfilled to the top of the pipe, the socket pressure test is performed again to check whether the pipeline is disturbed during the backfilling process, causing the socket to shift and thus resulting in a poor seal.

[0061] During the installation of the DN2400mmGRP pipeline of the XX 220,000 m³ liquefied natural gas (LNG) process plant project, the innovative use of the socket installation technology only requires two construction workers on both sides of the pipeline to pull at the same time, and one technician to master the socket size and pipeline positioning. Compared with the traditional hand paste connection, it can reduce the number of construction workers by 50% and reduce the construction cost by 30%. This connection method does not require waiting during construction and can be operated continuously, which greatly improves construction efficiency and can shorten the construction period by 30 days compared with traditional construction methods.

[0062] The present invention adopts a socket connection method, which is a soft connection with a certain elasticity. When the pipeline is subjected to an external force, there is a certain movable gap. The double "O" type rubber ring seal plays a double protection role for the pipeline seal. The pipeline foundation uses reinforced concrete piles, a cap, and medium-coarse sand to ensure that the pipeline does not undergo a large displacement, and the sand filling between the pipeline and the cap can play a certain buffering role for the pipeline, thereby ensuring the quality of the GRP pipeline installation and ensuring the long-term stable operation of the pipeline. The pipeline is not easily damaged during operation, thereby increasing its service life.

[0063] This method improves the sealing of the socket by adding pads to the concrete foundation and fixing the two sides of the pipe with spring brackets. The concrete foundation is filled with 200mm medium-coarse sand, and the pipe is supported by pads made of fine sand in woven bags on both sides of the socket and in the middle of the pipe. The foundation is leveled with a level to ensure the horizontality of the pipe during laying. Spring brackets are installed in the middle of the pipe on both sides of the pipe, and arc plates are made at the front end of the spring brackets to be clamped on the outer wall of the pipe. This method can reduce the axial and radial displacement of the pipe to improve the sealing of the socket.

[0064] This method reduces the settlement of the pipeline by adding lugs and foundation waterproofing on the foundation of the pedestal. Lugs with a height of 1000mm are made on both sides of the concrete pedestal, and waterproofing is laid on the inside of the pedestal and the lugs to prevent groundwater from entering the pipeline foundation. The sand filling inside the pipeline foundation is dispersed to ensure that the pipeline does not have large irregular settlement and the socket does not have large displacement, so as to better ensure the sealing of the socket.

[0065] This method uses expansion joints for flexible connection in the above-ground part to reduce the impact on the pipeline. Steel flange rubber expansion joints are installed at the blind plate of the mud cleaning port and the outlet of the seawater pump in the above-ground part to buffer the impact when the seawater pump is started and the water hammer force when the seawater reaches the blind plate of the pipeline, reduce the impact of equipment and water flow impact on the pipeline, and improve the stability of pipeline operation.

[0066] It should be noted that the above content only illustrates the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. A method for installing a large-diameter GRP seawater pipeline onshore with a spigot and socket connection, characterized in that: The following steps are involved: (1) GRP pipe prefabrication: GRP pipe is made of epoxy unsaturated resin, glass fiber mat and glass fiber cloth through winding molding. After the prefabrication of GRP pipe is completed, a reinforcing rib is added every 1m on the outside, and a groove for placing O-type rubber ring is processed at the plug position; waterproofing and ear picking are done well; (2) GRP pipe foundation production: The pipeline foundation is excavated to the designed elevation, the soil in the pile core is cleaned, the pile core cage is made, the cushion formwork is installed, the pile core and cushion concrete are poured, the cap steel bars are tied, and the cap formwork is installed. After the cap is poured, medium-coarse sand is backfilled on the cap, compacted with a small roller, and the sand filling in the cap is leveled; (3) Locate the tee position of the GRP pipe; (4) Pipeline hoisting and installation: First, install an O-shaped rubber ring at the socket position, tie it to the GRP pipe with a sling to make the GRP pipe horizontal, hook the hand chain hoist to the sling, and after the crane is lifted into place, use the reinforcement as the support point, use the hand chain hoist to pull both sides of the pipe at the same time, and finally the pipe socket is in place, add a pad on the concrete foundation and fix both sides of the pipe with a spring bracket to improve the sealing of the socket; (5) After the pipeline is installed in place, the socket is subjected to a water pressure test. If there is no pressure drop, the pressure test is qualified; (6) Pipeline backfilling.

2. A method for installing a large-diameter GRP seawater pipeline onshore with a spigot and socket joint according to claim 1, characterized in that: There are two grooves at the socket position in step (1).

3. The onshore socket-and-spigot installation method of a large-diameter GRP seawater pipeline according to claim 1, characterized in that: During the manufacturing process of the GRP pipe foundation in step (2), thrust piers are provided at the bends of the GRP pipe.

4. A method for installing a large-diameter GRP seawater pipeline onshore with a spigot and socket joint according to claim 3, characterized in that: The thrust pier is composed of bottom plate reinforcement, pipe annular reinforcement, and top layer reinforcement, and is cast outside.

5. The onshore socket-and-spigot installation method of a large-diameter GRP seawater pipeline according to claim 1, characterized in that: Step (3) While positioning the GRP pipe tee, position each crossing and socket, and add a protective sleeve at each crossing. During installation, use a hand winch to shift the GRP pipe through the entire protective sleeve.

6. The onshore socket-and-spigot installation method of a large-diameter GRP seawater pipeline according to claim 1, characterized in that: The pressure of the water pressure test in step (5) is 1.2 MPa. If the pressure is maintained for ten minutes and there is no pressure drop, the pressure test is qualified.

7. The onshore socket-and-spigot installation method of a large-diameter GRP seawater pipeline according to claim 1, characterized in that: When the pipeline is backfilled to the top of the pipe in step (6), the socket pressure test is performed again.

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