Pipeline classification and classification
Industrial pipeline pressure classification
Level Name Design Pressure P (MPa)
Vacuum pipe P<0
Low pressure pipeline 0≤P≤1.6
Medium pressure pipeline 1.6 High pressure pipeline 10 Ultrahigh pressure pipeline P>100 The composition of the pipeline Pipeline consists of pipe components and pipe supports Pipeline components Pipeline components are components used to connect or assemble pipes: pipes, fittings, seals, fasteners, valves, safety protection devices; expansion joints, flexible joints, pressure hoses, steam traps, filters; pipelines Throttling devices, separators, etc. Pipe support Pipeline support things transfer the weight of the pipe, the weight of the transported fluid, the load caused by operating pressure and temperature difference, and the load caused by vibration, wind force, earthquake, snow load, impact, and displacement strain, etc., to the pipe element on the pipe frame structure. : Hanger, spring hanger, constant force hanger, diagonal tie rod, balance hammer, elastic bolt, support rod, chain, rail, anchor, saddle, pad, roller, bracket, sliding bracket, tube Hangers, hangers, snap rings, pipe clamps, U-shaped clamps, splints, etc. Construction Program Preparation for construction → Cooperate with civil engineering reservation, pre-buried, measurement → Pipeline, bracket prefabrication → Accessories, flange processing, inspection → Pipe section prefabrication → Pipe installation → Piping system inspection → Piping system test → Anticorrosion insulation → System cleaning → Data summary, drawing As-built drawings → completion acceptance skills requirement Pipeline components and materials inspection Pipeline components and materials shall have the quality certificate of the manufacturer and comply with the provisions of the current national standards and design documents. Before use, check the material quality, specification, model, quantity and marking, and check the appearance quality and geometric dimensions. The marking should be clear and complete, and it can be traced back to the product quality certification document. The product quality certification documents for pipeline components include product certifications and quality certificates. The quality certification document should have a manufacturing unit quality inspection seal. The pipeline components that carry out supervision and inspection shall also provide the supervision and inspection certificates issued by the special equipment inspection and testing institutions. Pipe components of chromium-molybdenum alloy steels, nickel-containing alloy steels, nickel and nickel alloy steels, stainless steels, titanium and titanium alloys shall be subjected to spectral analysis or other methods for review and marking. Made of stainless steel, non-ferrous metal piping components and materials, which must not come in contact with carbon steel or low-alloy steel during transportation and storage The design documents stipulate the pipeline components and materials for low temperature impact toughness test, and the components and materials for stainless steel, nickel and nickel alloy steel for intergranular corrosion test. The supplier shall provide documents on the test results of low temperature impact toughness and intergranular corrosion resistance. The test results shall not be lower than the design documents Valve inspection Before the installation of the valve, appearance quality inspection should be carried out. The valve body should be in good condition, the opening mechanism should be flexible, and the stem should be free of skew, deformation, jamming, and the sign should be complete. The valve shall be subjected to shell pressure test and seal test. The valve shell pressure test and seal test shall be conducted with clean water as the medium. When the stainless steel valve is tested, the chloride ion content in water shall not exceed 25 ppm. The shell pressure test of the valve is 1.5 times the maximum allowable working pressure of the valve at 20°C. The seal test is 1.1 times the maximum allowable working pressure of the valve at 20°C. The duration of the test shall not be less than 5 minutes. When there is no special regulation, the temperature of the test medium is 5～40°C. If the temperature is lower than 5°C, the temperature should be increased. The inspection of the safety law shall be conducted in accordance with the provisions of the current national standards and design documents for setting pressure adjustments and sealing tests. Safety valve should be recorded, sealed and issued inspection report Industrial pipe construction technical requirements When industrial metal pipelines are connected, they must not use strong counterparts. The connection between the pipeline and the equipment shall be carried out after the equipment is installed and positioned and the anchor bolts are fastened. The pipeline equipment connection (such as air compressor, oxygen generator, steam turbine, etc.) shall not subject the equipment to additional external forces. Before the pipeline is connected with the mechanical equipment, the parallelism and coaxiality of the flange shall be checked in the free state, and the deviation shall comply with the specified requirements. When the pipeline and the mechanical equipment are finally connected, a dial indicator should be set up on the coupling to monitor the displacement of the machine. After passing the pressure test and purging, the pipeline shall be reset and checked for the interface between the pipeline and the machine. After the pipeline is installed, it must not bear any additional load outside the design Pipes of large storage tanks are connected to pumps or other independent basic equipment and should be installed after the tank hydraulic pressure (filled water) test passes. For the connection of non-metallic pipes, since the performance of pipes and fittings produced by different manufacturers may be different, the manufacturer should be consulted before preparing the connection process documents. The construction environment has a great influence on the connection quality of non-metallic pipelines. Therefore, construction should be avoided in harsh environments such as high or low temperatures, high winds, and strong direct sunlight. Valve installation Before the valve is installed, check the model according to the design documents, and determine the direction of the installation according to the direction of flow of the medium; check the filling of the valve, and leave adjustment margins for the gland bolts. When the valve and metal pipe are connected by flange or thread, the valve should be installed in the closed state; when connected by welding, the valve must not be closed, and the bottom layer of the weld should be used for argon arc welding. When the non-metallic pipe is fused or hot-melted, the valve near the joint should be open. The installation of safety valve shall meet the requirements of vertical installation, the outlet pipe of the safety valve shall be connected to a safe place, the seal shall be added when the stop valve is set on the access pipe, and shall be locked in the fully open state Support and hanger installation Supports and hangers should be flat and firm, and should be in close contact with the pipe Pipes without thermal displacement should be installed vertically. For pipes with thermal displacement, the lifting point should be set in the opposite direction of the displacement, and 1/2 offset according to the displacement value. The sliding surface of the guide bracket or sliding bracket should be clean and flat, without skew and jamming The spring height of the spring support and hanger shall be installed in accordance with the design documents, and the spring shall be adjusted to the cold state and recorded. Temporary fixing of springs, such as locating pins (blocks), should be removed after system installation, pressure testing, and thermal insulation are completed
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