1. Connection type：
1）Butt welding connection is to fix all the two parts after spot welding, of course, the welder's requirements are also slightly higher, because the butt welding needs to do 100% RT inspection under strict working conditions, Butt welding connection is common used in chemical oil, electric power, gas and steel industries.
2) Socket welding is to weld the pipe into the valve body for welding, and the shape of the internal thread connection is similar after molding. Generally speaking, carbon steel pipes and stainless steel pipes of 2" or less are used for socket welding. Stainless steel pipes are also used for butt welding below 2", such as flange flange flanges; titanium pipes, duplex steels, nickel bases. Alloys and the like are basically used for butt welding.
1) Socket welds form fillet welds, while butt welds form butt welds. It is better to analyze the butt joints from the strength and stress state of the welds than the sockets. Therefore, in the case of high pressure grades and occasions where the use conditions are bad, the form of docking should be adopted.
2) Socket welding is generally used for small diameters of DN40 or less, which is economical. Butt welding is generally used for DN40 or above. The form of socket welding is mainly used for small diameter valves and pipe, pipe fittings and pipe welding. Small-diameter pipes generally have a thin wall thickness, are easy to be misaligned and ablated, and are difficult to weld, and are more suitable for socket welding. In addition, the socket of the socket welding has a reinforcing effect, so it is also used under high pressure. However, socket welding also has shortcomings. One is that the stress condition after welding is not good, the welding is not welded, and there are gaps inside the pipe system. Therefore, the pipe system used for crevice corrosion sensitive media and the pipeline system with high cleaning requirements are not suitable. Use socket welding. Furthermore, for ultra-high pressure pipes, even small-diameter pipes have a large wall thickness, and it is possible to avoid socket welding by using butt welding.
3) The former must be one big and one small in diameter before it can be inserted into the weld. The latter diameters may be the same or different. 2. The welding groove is different in form. 3 welding process is different. The strength after welding is different.
4) Most of the lower pressure grades are smaller socket welds, and the higher pressure grades are often butt welds. Butt welds are 100% tested for flaw detection to ensure no leaks.