Do you know how many different ways there are to connect valves to pipelines?

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The way in which the entire valve is connected to the pipelines or equipment cannot be ignored, as the majority of leaks and failures related to valves occur at this connection point. 1 Flange connection: The flange connection is the most commonly used type of connection between valves and pipelines or equipment. It refers to a detachable connection that forms a combined sealing structure through the mutual connection of flanges, gaskets, and bolts. Pipe flanges refer to the flanges used for piping in pipeline systems, while those used on equipment refer to the inlet and outlet flanges of the equipment. Flange connections are easy to use and can withstand high pressures. Flange connections can be used for valves of various nominal sizes and pressures, but there are certain limitations regarding the operating temperature. At high temperatures, the connection bolts of the flanges may experience creep, leading to leaks; therefore, flange connections are generally recommended for use at temperatures up to 350°C. Based on the shape of the joint surface, they can be further divided into the following types: Smooth type: used for valves with low pressure. It is relatively easy to process. Convex-concave type: It operates under high pressure, and medium-hard washers can be used. Grooved type: Washers with greater plastic deformation can be utilized; it is widely used in corrosive media and provides good sealing performance. Trapezoidal groove type: Elliptical metal rings are used as washers, and it is applied to valves with a working pressure of ≥60 kg/square centimeter or high-temperature valves. Lens type: The washer is in the shape of a lens and is made of metal. Used for high-pressure or high-temperature valves with a working pressure of ≥100 kilograms per square centimeter. O-ring type: A newer type of flange connection, offering a more reliable sealing effect compared to ordinary flat gaskets. Two-clamp connection: A connection method in which the valve and the pipes at both ends are fastened together directly using bolts. 3 Welded connection: A welded connection refers to a type of connection in which the valve body has welding grooves, and it is connected to the pipeline system through welding. Standards such as GB/T 12224, API600, and ASME B 16.34 specify requirements for welding grooves. The welded connections between valves and pipes are divided into butt welding (BW) and socket welding (SW), with the socket welding ends having to comply with the requirements of JB/T 1751. Butt welding (BW) can be used for valves of various sizes, under different pressure conditions as well as in high-temperature environments, while socket welding (SW) is generally suitable for valves with a diameter of ≤DN50. 4 Threaded connection: This is a simple method of connection, commonly used for small valves. There are also two cases: direct sealing: the internal and external threads serve as a seal directly. To ensure that the joints do not leak, they are often filled with lead grease, linen rope, and PTFE tape, among which PTFE tape is widely used. This material has excellent corrosion resistance and a superb sealing effect; it is easy to use and store. When removed, it can be taken off completely, as it is a non-sticky film, making it far superior to lead-based oils and hemp fibers. Indirect sealing: The force generated by tightening the threads is transmitted to the gasket located between the two surfaces, allowing the gasket to perform the sealing function. 5. Collar connection: The working principle of the collar connection is that when the nut is tightened, pressure is applied to the collar, causing its cutting edges to bite into the outer wall of the pipe. Meanwhile, the external conical surface of the collar fits tightly against the internal conical surface of the fitting under this pressure, thereby ensuring reliable leakage prevention. The advantages of this type of connection are: 1) small size, light weight, simple structure, and easy assembly and disassembly ； 2) Strong bonding strength, wide range of applications, capable of withstanding high pressure (1000 kilograms/square centimeter), high temperatures (650°C), and shock vibrations ； 3) Various materials can be used, making it suitable for corrosion resistance ； 4) The requirements for processing precision are not high ； 5) Facilitates installation at high heights. ? ? ? ?At present, the ferrule connection type has been adopted in some small-diameter valve products in our country. 6-clamp connection: This is a quick-connect method that requires only two bolts, and it is suitable for low-pressure valves that are frequently disassembled. 7 Internal self-tightening connection: An internal self-tightening connection is a type of connection that utilizes medium pressure to achieve self-tightening. Its sealing ring is located at the inner cone, at an angle to the side facing the medium. The pressure of the medium is transmitted to the inner cone, which in turn passes it on to the sealing ring. On the conical surface at this angle, two forces are generated: one that pushes outward parallel to the center line of the valve body, and another that presses against the inner wall of the valve body. The latter component of force is the self-tightening force. The greater the medium pressure, the greater the self-tightening force. Therefore, this type of connection is suitable for high-pressure valves. It saves a lot of material and labor compared to flange connections, but it also requires a certain degree of pre-tensioning in order to function reliably when the pressure inside the valve is not high. Valves made using the self-sealing principle are generally high-pressure valves. There are many other ways in which valves can be connected; for example, some small valves do not need to be removed and are welded directly to the pipes ； Some non-metallic valves use socket-type connections, and so on. Valve users should handle the situation according to specific circumstances. 8 Other: There are many other types of valve connections; for example, some small valves that do not need to be removed are welded directly to the pipes ； Some non-metallic valves use socket-type connections, and so on. Valve users should handle the situation according to specific circumstances.