Construction Method for Pipe Installation of Pipeline Connected to Heating Equipment

Abstract

The present invention discloses a construction method for the installation of connecting pipes between pipelines and heating equipment, including steps such as pipeline installation, pipeline welding, and the installation of connecting pipes for heating equipment. The parallel deviation of the flange end face is not greater than 1.5% of the outer diameter of the flange and shall not be greater than 2 mm; the pipeline is inserted into 2 / 3 of the flange thickness, and the inner diameter of the flange is 2 - 4 mm larger than the outer diameter of the pipe; when butt-welding seamless steel pipes and when assembling adjacent cylinder sections of containers and steel plate rolled pipes, the longitudinal seams are staggered by more than 100 mm from each other, and the distance between two adjacent longitudinal seams on the same cylinder section of containers and steel plate rolled pipes must be greater than 300 mm; by using the horizontal and vertical turning points and branch points of the connecting pipes, the axial direction deviation of the connecting pipes from the inlet and outlet positions of the equipment is adjusted, and by using short flange pipes, the radial deviation between the connecting pipes and the equipment flanges is adjusted. The present invention can effectively prevent the parallel deviation, radial displacement, and excessive spacing of the equipment interface flanges, eliminate the harm to heating equipment caused by the additional stress generated by the connecting pipes, and eliminate the phenomenon of equipment flange rupture caused by improper connecting pipes.

Description

Technical Field:

[0002] The present invention relates to a construction method, and particularly to a construction method for installing connecting pipes between pipelines and heating equipment. Background Art:

[0004] With the rapid economic development, in the face of the international upsurge in geothermal energy development and utilization and the huge domestic demand for clean energy, pipeline installation projects are a new model emerging in recent years. When installing connecting pipes between pipelines and heating equipment, the basic requirement is to ensure that the equipment operates under a stress-free state. If the additional stress generated by the connecting pipes on the heating equipment exceeds the allowable stress specified in the standard, it will affect the normal operation of the equipment. In severe cases, it may cause damage to the cleaning equipment. Therefore, higher requirements are put forward for the parallel deviation, radial displacement, and spacing of the flange installation at the interfaces (inlet and outlet) of the heating equipment. Summary of the Invention:

[0006] The technical problem to be solved by the present invention is to provide a construction method for installing connecting pipes between pipelines and heating equipment, which can effectively prevent the parallel deviation, radial displacement, and excessive spacing of the flange at the equipment interface, and eliminate the harm caused by the additional stress generated by the connecting pipes to the heating equipment.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] A construction method for installing connecting pipes between pipelines and heating equipment, comprising the following steps:

[0009] Step 1: Pipeline installation:

[0010] ① The end face of the pipeline cut is flat, without cracks, double skins, burrs, and the slag must be removed cleanly; the surface of the elbow

[0011] shall not have cracks, delamination, or double skin phenomena, and the transition is smooth and the surface is smooth and clean;

[0012] ② The flange sealing surface and the sealing gasket shall have no sand holes, cracks, or radial scars, the positions of the screw holes are correct, and the joint surface has a water line;

[0013] ③ The flange end faces are kept parallel, and the deviation is not greater than 1.5% of the outer diameter of the flange and shall not be greater than 2 mm;

[0014] ④ The pipeline is inserted into 2 / 3 of the flange thickness, the inner diameter of the flange is 2 - 4 mm larger than the outer diameter of the pipe, and the inner side of the flange is welded for bottom sealing;

[0015] ⑤ The gasket remains intact, without wrinkles, cracks, or creases and other defects, and is soaked in machine oil for 24 hours before use; before adding the gasket, the convex surface of the flange is brushed smooth and the water line is scraped clean; the gasket is placed flat and cannot use an offset gasket or a double gasket;

[0016] ⑥When tightening the bolts, tighten them symmetrically and evenly, and the nuts should be on the same plane of the flange.

[0017] ⑦Add a flange plate to the drain pipe opening and install a blanking plate for plugging; the drain opening should face the wellhead or the direction convenient for draining water to facilitate connecting the pipe for draining water.

[0018] Step 2: Welding of pipes

[0019] ①The welds on the pipe must be located at positions convenient for welding, inspection, and maintenance, and avoid areas with stress concentration.

[0020] ②When butt-welding seamless steel pipes and when assembling adjacent cylinder sections of containers and steel plate rolled pipes, the longitudinal seams must be staggered by more than 100 mm from each other.

[0021] ③The distance between two adjacent longitudinal seams on the same cylinder section of a container or a steel plate rolled pipe must be greater than 300 mm.

[0022] ④The distance between the centers of two adjacent circumferential welds of pipes in the trench and above the ground must be greater than the outer diameter of the steel pipe and not less than 150 mm.

[0023] ⑤There should be no circumferential welds within 500 mm of the pipe support, and there should be no cross-shaped welds at any position of the pipe.

[0024] ⑥When welding a branch on a seamless steel pipe, the distance between the outer wall of the branch pipe and the center of other welds must be greater than the outer diameter of the branch pipe and not less than 70 mm.

[0025] ⑦When butt-welding the pipe ends, the straightness of the pipe must be checked. Measure at a distance of 200 mm from the center of the butt joint. The allowable deviation of straightness is 1 mm, and within the entire length of the butt-welded steel pipe, the maximum allowable deviation does not exceed 10 mm.

[0026] ⑧After the butt joint is qualified, spot welding is carried out. For butt welds with D ≤ 2", all are welded by argon arc welding; for butt welds with D > 2", all are welded by arc welding.

[0027] ⑨The surface of the weld must not have cracks, pores, slag inclusions, and the depth of undercut is less than or equal to 0.5 mm.

[0028] Step 3: Installation of connecting pipes for heating equipment

[0029] ①First, connect the interface flange of the connecting pipe and the equipment by standard bolts. After the interface flange is fastened to the equipment flange, then carry out spot welding with the flange short pipe. During welding, argon gas with a purity of more than 99% is filled in the pipe for protection.

[0030] ②Utilize the horizontal and vertical turning points and branch points of the connecting pipe to adjust the axial direction deviation of the positions of the connecting pipe and the inlets and outlets of the equipment.

[0031] ③Utilize the flange short pipe to adjust the radial deviation between the connecting pipe and the equipment flange.

[0032] ④For pipes with high cleanliness requirements, to avoid the formation of welding beads and welding slag inside the pipeline at the welds, gas shielded welding is used. During welding, argon gas with a purity of over 99% is filled inside the pipe for protection, and it is purged with compressed air before installation.

[0033] In Step 3, when installing the interface flange, the flange bolts are tightened in a symmetric order so that the bolts are evenly stressed.

[0034] The positive and beneficial effects of the present invention are as follows:

[0035] 1. The present invention can effectively prevent the parallel deviation, radial displacement, and excessive spacing of the equipment interface flange, and eliminate the harm to the heating equipment caused by the additional stress generated by the piping.

[0036] 2. Ensure the cleanliness inside the pipes of the connecting pipes of the heating equipment, and improve the product quality.

[0037] 3. Eliminate the phenomenon of equipment flange rupture caused by improper piping.

[0038] 4. The construction method is simple to operate and easy to master.

[0039] The scope of application of the present invention:

[0040] 1. Applicable to the installation of pipes connected to drive equipment.

[0041] 2. Can also be used for the installation of pipes connected to stationary equipment.

[0042] 3. The installation of pipe fittings such as valves, short pipes, reducing pipes, and flanges on the branch pipes of the pipeline.

[0043] Test application cases of the present invention:

[0044] From February to June 2019, during the installation construction of the clean central heating equipment pipeline in a certain community in the Economic Development Zone of Zhengzhou City, this construction method was adopted for all the pipeline connection constructions with the heating equipment, serving 11 central heating station rooms, and there were more than 400 piping pipes. Among them, the heat supply pipelines were seamless steel pipes and spiral welded steel pipes, and those with a pipe diameter above DN50 accounted for 90%. After quality acceptance and settlement, all the parallel deviations, radial displacements, and spacing deviations of the clean equipment interface flanges met the specifications, the equipment operated normally, and the excellent product rate reached over 90%, meeting the ministerial excellent standard. Specific implementation manners:

[0046] The following further explains and illustrates the present invention in combination with specific embodiments:

[0047] Embodiment: A construction method for the installation of pipes connecting a pipeline and a heating equipment, including the following steps:

[0048] Step 1. Pipeline installation:

[0049] ① The end face of the pipe cut shall be flat, without cracks, double skins, burrs, and the slag must be removed cleanly; for the elbow pipe

[0050] the surface shall not have cracks, delamination, or double skin phenomenon, and shall be overly smooth with a smooth surface finish;

[0051] ② For the flange sealing surface and the sealing gasket, there shall be no sand holes, cracks, or radial scars, the positions of the screw holes shall be correct, and there shall be a water line on the mating surface;

[0052] ③ The flange end faces shall be kept parallel, with a deviation not greater than 1.5% of the flange outer diameter and not greater than 2 mm;

[0053] ④ The pipe shall be inserted into 2 / 3 of the flange thickness, the inner diameter of the flange shall be 2 - 4 mm larger than the outer diameter of the pipe, and the inner side of the flange shall be welded for bottom sealing;

[0054] ⑤ The gasket shall remain intact, without defects such as wrinkles, cracks, and creases, and shall be soaked in machine oil for 24 hours before use; before adding the gasket, the convex surface of the flange shall be brushed smooth and the water line shall be scraped clean; the gasket shall be placed flat and no offset gaskets or double gaskets shall be used;

[0055] ⑥ When tightening the bolts, tighten them symmetrically and evenly, and the nuts shall be on the same surface of the flange;

[0056] ⑦ A flange plate shall be added to the drain pipe opening and a plug plate shall be set for blocking; the drain opening shall face the wellhead or the direction convenient for draining water to facilitate connecting the pipe for draining water;

[0057] Step 2: Pipe welding:

[0058] ① The welds on the pipe shall be located at positions convenient for welding, inspection, and maintenance, and shall avoid stress concentration areas;

[0059] ② When butt-welding seamless steel pipes and when assembling adjacent cylinder sections of containers and steel plate rolled pipes, the longitudinal seams shall be staggered by more than 100 mm from each other;

[0060] ③ The distance between two adjacent longitudinal seams on the same cylinder section of a container or a steel plate rolled pipe shall be greater than 300 mm;

[0061] ④ The distance between the centers of two adjacent circumferential welds of pipes in the trench and above the ground shall be greater than the outer diameter of the steel pipe and not less than 150 mm;

[0062] ⑤ There shall be no circumferential welds within 500 mm of the pipe support, and there shall be no cross-shaped welds at any position of the pipe;

[0063] ⑥ When welding a branch on a seamless steel pipe, the distance between the outer wall of the branch pipe and the center of other welds shall be greater than the outer diameter of the branch pipe and not less than 70 mm;

[0064] ⑦When butt-welding the pipe ends, the straightness of the pipe must be checked. Measure at a distance of 200 mm from the center of the butt joint. The allowable deviation of straightness is 1 mm. Within the entire length of the steel pipe being butt-welded, the maximum allowable deviation shall not exceed 10 mm.

[0065] ⑧After the butt joint is qualified, spot welding is carried out. For butt welds with D ≤ 2”, all are welded by argon arc welding; for butt welds with D > 2”, all are welded by arc welding.

[0066] ⑨There shall be no cracks, pores, or slag inclusions on the surface of the weld, and the depth of undercut shall be less than or equal to 0.5 mm.

[0067] Step 3: Installation of the connecting pipe for the heating equipment:

[0068] ①First, connect the interface flange of the connecting pipe and the equipment through standard bolts. After the interface flange is fastened to the equipment flange, then carry out spot welding with the flange short pipe. During welding, argon gas with a purity of more than 99% is filled in the pipe for protection.

[0069] ②Utilize the horizontal and vertical turning points and branch points of the connecting pipe to adjust the axial direction deviation of the positions of the connecting pipe and the inlets and outlets of the equipment.

[0070] ③Utilize the flange short pipe to adjust the radial deviation between the connecting pipe and the equipment flange.

[0071] ④For the connecting pipe with higher cleanliness requirements, to avoid the formation of welding beads and welding slag inside the pipe at the weld, gas shielded welding is adopted. During welding, argon gas with a purity of more than 99% is filled in the pipe for protection, and it is purged with compressed air before installation.

[0072] In Step 3, when installing the interface flange, fasten the flange bolts in a symmetric order so that the bolts are evenly stressed.

[0073] The present invention can effectively prevent the parallel deviation, radial displacement, and excessive spacing of the equipment interface flange, eliminate the harm to the heating equipment caused by the additional stress generated by the connecting pipe, ensure the cleanliness inside the connecting pipe of the heating equipment, improve the product quality, eliminate the phenomenon of equipment flange rupture caused by improper connecting pipe, and the construction method is simple and easy to master.

Claims

1. A method for installing a pipe connecting a pipeline to a heating device, comprising the following steps: Step 1: Pipeline installation: ① The end surface of the pipe cut should be smooth without cracks, heavy skin, burrs, and the slag should be cleaned; The surface should not have cracks, delamination, or heavy skin, and should be overly smooth and have a smooth surface; ② The flange sealing surface and sealing gasket must be free of sand holes, cracks or radial scars, the screw holes must be in the correct position, and there must be a waterline on the joint surface; ③ The flange end faces should remain parallel, with a deviation of no more than 1.5% of the flange outer diameter and no more than 2 mm; ④The pipe is inserted into 2 / 3 of the flange thickness, the inner diameter of the flange is 2-4 mm larger than the outer diameter of the pipe, and the inner side of the flange is welded; ⑤ The gasket should be kept intact, without wrinkles, cracks or creases, and soaked in engine oil for 24 hours before use; before adding the gasket, the flange convex surface should be brushed and polished smooth, and the waterline should be scraped clean; the gasket should be placed flat, and offset gaskets and double gaskets should not be used; ⑥ When tightening the bolts, tighten them symmetrically and evenly, with the nuts on the same side of the flange; ⑦ The drain pipe outlet should be equipped with a flange and sealed with a plugging plate; the drain outlet should face the wellhead or a direction convenient for draining water, so as to facilitate pipe connection and draining water; Step 2: Pipeline welding: ① The welds on the pipeline must be located in a position that is convenient for welding, inspection, and maintenance, and avoid areas of stress concentration; ② When the joints of seamed steel pipes and adjacent sections of containers and steel plate coils are assembled, the longitudinal seams must be staggered by more than 100 mm; ③ The distance between two adjacent longitudinal seams on the same tube section of the container and steel plate coil must be greater than 300mm; ④ The distance between the centers of two adjacent annular welds of the trench and the ground pipeline must be greater than the outer diameter of the steel pipe and cannot be less than 150mm; ⑤ There should be no circular welds within 500mm of the pipe support, and no cross welds at any position of the pipe; ⑥ When welding branches on seamed steel pipes, the distance between the outer wall of the branch pipe and the center of other welds must be greater than the outer diameter of the branch pipe and must not be less than 70 mm; ⑦ When the pipes are butt-jointed, the straightness of the pipes must be checked and measured at a distance of 200mm from the center of the butt joint. The allowable deviation of the straightness is 1mm. Within the full length of the butt joint steel pipe, the maximum allowable deviation shall not exceed 10mm. ⑧ After the butt joints are qualified, spot welding is carried out. For butt joints with D≤2", argon arc welding is adopted, and for butt joints with D>2", electric arc welding is adopted; ⑨ There shall be no cracks, pores or slag inclusion defects on the weld surface, and the undercut depth shall be less than or equal to 0.5mm; Step 3: Heating equipment connection piping installation: ①First, connect the interface flanges connecting the piping and the equipment with standard bolts. After the interface flanges are fastened to the equipment flanges, spot weld them with the flange short pipes. During welding, fill the pipes with argon gas with a purity of more than 99% for protection; ② Use the horizontal and vertical turning points and branch points of the piping to adjust the axial direction deviation between the piping and the inlet and outlet positions of the equipment; ③ Use flange short pipe to adjust the radial deviation between the pipe and the equipment flange; ④ For piping with high cleanliness requirements, gas shielded welding is used to avoid weld nodules and welding slag inside the pipe. During welding, argon gas with a purity of more than 99% is filled in the pipe for protection, and compressed air is used for purge before installation.

2. The pipe connection and installation construction method for heating equipment according to claim 1, characterized in that: In step 3, when installing the interface flange, tighten the flange bolts in a symmetrical order so that the bolts are evenly stressed.