Flange connection refers to the two pipe, pipe fittings or equipment, the first of their fixed in a flange plate, the two flange, with the pad, with bolts to fasten them together, complete the connection. Some pipe products and equipment have own flange plate, also belong to the flange connection. Flange is divided into threaded flange and welding flange, it is a kind of disk shaped parts, in the pipeline project is the most common, the flange is used in pairs. In the pipeline project, the flange is mainly used for the connection of the pipe. In the need to connect the pipe, a variety of installation of a flange plate, low pressure pipe can be used wire connection flange, 4 kg or more pressure on the use of welding flange. Low voltage and small diameter wire connecting flange, high pressure and low pressure and large diameter are welded flange, the thickness of the flange plate of different pressure and the connecting bolt diameter and the number is different. Flange is not produced corrosion, pitting, corrosion or wear, and is one of the highest strength of the materials used in building materials. Because the stainless steel has good corrosion resistance, so it can make structural components to maintain the integrity of Engineering design.

Flanges can not be stored for a long time, should be regularly inspected, often on the exposed machined surfaces shall be maintained in a clean, remove dirt, neatly stored in indoor and ventilated and dry place, stacked or open storage is prohibited. Flange of the ball valve, globe valve, gate valve is used, only for fully open or fully closed, do not agree to do to adjust the flow, so as to avoid the sealing surface by erosion, accelerated wear and tear. Materials of the flange is convenient, simple manufacture, low cost, wide use; but less rigid. Therefore, it cannot be used for supply and demand, flammable, explosive and high vacuum degree requirements of chemical process piping system and height, is extremely harmful to the occasions. Seal type plane and surface process. The flange has the advantages of simple structure, small volume, light weight, compact and reliable, the current valve sealing surface material widely used plastic, sealing, in the vacuum system has also been widely used; easy maintenance, valve structure is simple, seals are generally activities, the removal of the replacement is more convenient; in the fully open or fully closed, the ball and seat sealing surface and the dielectric isolation.