Generally in the case of customers without special requirements, the connecting flange of the valve is cast together with the valve, which is called the integral flange, is also the most commonly used flange connection; Flat welded flange due to low structural strength, stiffness, more used in the conditions of moderate conditions, such as low pressure circulating water valve, general low pressure compressed air valve, and its advantages are low price, convenient installation,Such as flange end ceramic rotating disc gate valve,flange end ceramic twin disc gate valve,flange end ceramic lined ball valve,.etc.

Threaded flanges can be used within the range of DN150. The applicable working conditions are similar to those of flat welded flanges, but the sealing and accurate positioning of threaded flanges are difficult to achieve. Therefore, when the pipe is required not to have any leakage, threaded flanges are generally not considered.

Socket welding is very common in the small size of the flange, this kind of flange is easy to install and welding, but cannot be used for poisonous fluids, because it is difficult to for weld radiographic, also cannot be used for can lead to corrosion or corrosion problems caused by fluid pipe, often used in pipelines without dangerous fluids less than or equal to PN100 and less than or equal to DN50;
The butt welding flange has good neck transition structure strength and stiffness, can be connected with the pipe butt welding and easy to carry out radiographic inspection, so that it has a high integrity, so it can be applied to more demanding occasions, such as oil and gas and chemical media.


When the temperature exceeds 350 ° C, due to the creep relaxation of bolts, gaskets and flanges, the load will be reduced on the bolts at any time . In this case, high temperature resistant bolt materials should be selected.