Large flange is a large diameter flange divided into several arc segments for processing. First of all, the blank forging billet, then cold forming arc, after annealing stress after heat treatment, the whole circle together again in the car for the processing of shape and size, the final design, several arc welding group for the integrity of the flange, and pressure vessel welding. It needs to be explained that because the large flange is bulky and inconvenient to transport, the whole machining is impractical, and the method of sectional machining must be adopted.
That is, for large pressure vessel flange, flange sealing surface to ensure the machining accuracy and smoothness, and completed in the main processing flange flange and head welding is completed, also need to pass a large vertical lathe for flange sealing surface finishing.
Large flange material is stainless steel 304, 316, 201, 321, 316L, 304L and other materials, A3, Q235, A105 steel and 10#, 20#, Q345, A182, 16MN and other materials, alloy steel 12Cr1MoV, 15crmov910, 15Mo3 15CrMoV, 12CrMoV, 45Cr, 50Cr and other materials.
In the process, should be put in the plate cutting into the right note, note the flange size is determined according to the specification, then the sliver coiling for roll ring circle using the machine, and then the electrode at the interface of solid welding, the weld must pass through the X spectrum test. Next, press it with a press, and then finish with the lathe, such as chamfering, machining the waterline and other processes. Then, the hole of the bolt hole is drilled with the dividing plate and the drilling machine, and the bolt hole can not be punched at the position of the welding hole.
Large diameter flange has common flange and butt welding flange. There is no large diameter threaded flange. In the production and sale of reality, or welding products accounted for much. The range of structure and use of welding of large diameter flange and butt welding of large diameter flange is different, can show the characteristics and advantages will be different, so when used according to different scope of use, which play an important role in the flange. Steel is large diameter flange, suitable for pressure P is less than or equal to 4MPa occasion; also called high neck flange welding flange, large rigidity, suitable for high temperature pressure.