Carbon Steel Cast Iron Flange Blind Plate DN20/25/32/40-200 Support Non-Standard Customized Cover Plate GB DN20 11mm

Butt welding with neck (WN)
Butt welding flange: Neck flange welding is often called "high junction" flange. The purpose is to transfer pressure to the pipe, thereby reducing the high stress concentration in the flange base. Neck flange welding is the best design for butt welding those supplied with flanges due to their inherent structural value. However, the price is relatively high, because the production process of the product is complex.
Threaded flange: The threaded flange is connected by a thread. But the center of the product has a thread size corresponding to the pipe. Its main advantage is that it can be assembled without welding.
Sliding flanges: Sliding flanges have lower pivots as pipes enter the single flange before welding. This is welded inside and outside to provide sufficient strength and prevent leakage. Sliding flanges are boring to match slightly larger od pipes. They are superior to the welding of neck flanges, due to the lower initial cost for many users, but the final installation cost probably will not be low, because the increased welding of neck flanges is less.
Lap flange: The lap flange is actually exactly the same as the sliding flange, except that it is a radius between the hole and the flange race. It is necessary for the radius to have a flange to accommodate the lap stub end. Usually, lap flanges and lap stubs will be mated together at the end of the assembly system.
The socket weld flange is similar to a sliding flange unless it has a hole and reverse hole dimensions. Counter holes are matched to the pipe so that the pipe is inserted into the flange similar to the sliding flange. The diameter of the smaller hole is the same as the ID of the same pipe match. The limit is built into the hole, which stays at the bottom as a shoulder sleeve designed for piping. This eliminates any flow restrictions when using socket welded flanges.