Large diameter flange connection is an important connection method for pipeline construction. Flange connection is to fix two pipe fittings or equipment on a flange plate first, add flange pads between the two flange plates, and fasten them together with bolts to complete the connection. Some pipe fittings and equipment have their own flanges, which are also flange connections. Flat welding flanges are divided into threaded (wire) flanges and welding flanges. The low-pressure small diameter has a wire flange, and the high-pressure and low-pressure large diameters use welding flanges. The thickness of the flange plate of different pressures and the diameter and number of connecting bolts are different. According to the different grades of pressure, flange pads also have different materials, ranging from low-pressure asbestos pads to high-pressure asbestos pads to metal pads. Flange connection is easy to use and can withstand large pressure. In industrial pipelines, flat welding flange connection is widely used. In the home, the pipe diameter is small and low pressure, and the flange connection is not visible. If in a boiler room or production site, flanged pipes and equipment are everywhere
The neck butt welding flange technology mainly includes: casting flange mainly includes # forging die forging flange cutting flange. The main application of the neck butt welding flange: the connection of the pipeline. On the pipeline to be connected, a variety of flanges are installed. The low-pressure pipeline can use the flange of the wire connection, and the pressure of more than 4 kg can be used with the neck. Butt welding flange. A sealing point can be added between the two-piece flanges, and then fastened with bolts.
Open hearth steel: P; boiling steel: F static steel: B; Class A steel: A; T8 means special 8; GCr15 means ball and so on. Combined steel spring steel, for example: 20CrMnTi60SiMn. The content of C in the butt welding flange is expressed in ten thousandths.
The following introduces the relevant information about butt welding flange products. It is a forced sealing valve. If the valve is closed, be sure to apply pressure to the disc to prevent leakage. If the medium enters the valve circuit from under the disc, the resistance to the operating force is the thrust produced by the friction between the valve stem and packing and the pressure of the medium. The force to close the valve is greater than the force to open it. Therefore, the diameter of the valve stem is large. Otherwise, the phenomenon of valve stem top bending will occur.
The plate flange is called blind plate or blind flange for short. The middle of the blind plate flange is solid, surrounded by bolt holes, and the appearance is like an iron cover, so it is also called flange cover. Large diameter flanges can usually be divided into wire joints There are two forms of flange and welding flange. The so-called “wire connection” refers to the form of threaded connection. If it is distinguished according to the two indicators of withstand pressure and diameter, in production practice, high-pressure or low-pressure large-diameter flanges generally use welding methods, while low-pressure small-diameter flanges mostly use wire connection. In addition, the thickness of the flange and the number and diameter of the connecting bolts are also related to the pressure. In the heat treatment of large-diameter flanges and other flanged pipe fittings, heating temperature is a very critical indicator. The selection and control of heating temperature involves the quality of heat treatment and the final product quality. Therefore, in large-diameter flanges and other pipe fittings In the heat treatment process, how to choose the appropriate heating method and how to control the heating temperature are issues that we need to pay special attention to.
The surface should be washed with clean pure water or acid until the dark blue color disappears completely. As pointed out in standard A380 [3], if the rust test solution cannot be completely removed, it is not recommended to be used on the process surface of the equipment. A relatively simple test method is to expose it to water for 12 to 24 hours to check for rust spots. This test has poor sensitivity and is time consuming. These are detection tests, not cleanup methods. If iron is found, it must be cleaned by chemical and electrochemical methods described later. The machining process of the welding flange is not difficult to process the welding flange. When processing the flange neck, it is necessary to align the supporting plate of the tool part with the processing degree. We have a simple formula for machining here: root neck size-mouth neck size/neck height size.
The socket weld flange is a similar slip flange, except it has a hole and counter hole size. The counter hole matches the pipe so that the pipe is inserted into the flange like a slip flange. The diameter of the smaller hole is the same as matching that of the same pipe with the same ID. The restriction is built into the hole, as a shoulder sleeve designed for pipes rests on the bottom. This eliminates any flow restriction when using socket weld flanges. The lap flange is actually exactly the same as the slip flange, except it has a radius between the hole and the flange race. It is necessary that the radii have flanges to accommodate the lap stub ends.
