Factors to consider when selecting a pipe


Pipe-Pipe Diameter Determination When the flow rate of […]

Pipe-Pipe Diameter Determination When the flow rate of a fluid is known, the size of the pipe diameter depends on the allowable flow rate or the allowable frictional resistance (pressure drop). When the flow rate is large, the pipe diameter is small, but the pressure drop value is increased. Therefore, when the flow rate is large, the investment in pipeline infrastructure can be saved, but the operating energy cost of power equipment such as pumps and compressors increases. In addition, if the flow rate is too large, there may be some other unfavorable factors. Therefore, the pipe diameter should be determined based on construction investment, operating costs and other technical factors. The connection method between the pipe-pipe joint pipe, the pipe coupling, the valve and the inlet and outlet pipe on the equipment is determined by the nature of the fluid, the pressure and temperature, and the material, size and installation location of the pipe, mainly with threaded connection and method. Four methods: blue coupling, socket coupling and welding: 1 threaded connection: mainly suitable for small diameter pipes. When connecting, it is generally necessary to wrap the fluoroplastic sealing tape or apply thick lacquer and wrap the sealing material on the threaded joint to prevent leakage.

At pressures above 1.6 MPa, a gasket seal is typically applied to the end of the tube. This type of coupling method is simple and can be disassembled and reassembled, but the joints must be installed in the appropriate places of the pipe to facilitate disassembly and assembly. 2 Flange connection: The applicable diameter range is large. When connecting, select different flanges and gaskets according to the nature, pressure and temperature of the fluid, and use bolts to clamp the gasket to keep the seal. Flange connections are mostly used in pipe sections that require frequent disassembly and where piping and equipment are connected. 3 socket connection: used for the connection between cast iron pipe, concrete pipe, clay pipe and its couplings, only for water supply, drainage and gas pipelines working under low pressure and normal temperature conditions.

When connecting, generally insert the hemp, cotton or asbestos rope in the groove of the socket, then fill it with asbestos cement or lead material, and fill the rubber seal ring in the socket to make it better. The flexibility allows for a small amount of movement of the tube Pipeline-pipeline laying in the city Water supply, drainage, heating, gas supply pipelines and long-distance oil and gas pipelines are mostly laid underground, and the process pipes in the factory are easy to operate and repair more on the ground. . Pipeline travel, support, slope and drainage, compensation, insulation and heating, corrosion and cleaning, identification and painting, and safety are important issues for both above-ground and underground laying. Access problems The pipes on the ground should be avoided as much as possible to cross roads, railways and waterways. When crossover cannot be avoided, the height of the crossing should also allow pedestrians and vehicles to pass safely. Underground pipelines are generally laid along roads, and various pipelines are kept at appropriate distances for installation and maintenance. The surface of the heating pipelines is insulated and laid in the trenches or protective pipes. It should be prevented from being crushed by the soil and the pipes can be expanded. mobile.

Supporting problems Pipes may be subjected to a variety of external forces, including their own weight (pipes, valves, pipe couplings, insulation and the weight of the fluid in the pipe), the pressure of the fluid acting on the pipe end, the snow load, the soil pressure, the heat Thermal stress, vibration load and earthquake disaster caused by expansion and contraction. In order to ensure the strength and rigidity of the pipeline, various support (hanging) brackets, such as movable brackets, fixed brackets, guide brackets and spring brackets, must be provided. The setting of the bracket is determined by the diameter, material, wall thickness and load of the pipe. The fixed bracket is used to control the thermal elongation of the pipe in stages, so that the expansion joint works evenly. The guide bracket allows the tube to move only axially. Slope and draining exhaust In order to exclude condensate, steam and other water-containing gas pipelines should have a certain slope, generally not less than two thousandths. For underground drainage pipes that use gravity to flow, the slope is not less than five thousandths. Steam or other water-containing gas pipelines are provided with drains or traps at the lowest point. Some gas pipelines are also equipped with gas-water separators to remove water in time to prevent water hammer and obstruct the gas flow. The water supply or other liquid pipeline is provided with a venting device at the highest point to exclude air or other gas accumulated in the pipeline to prevent the gas barrier from causing malfunction.