Butt welding flange: neck flange welding is usually called "high hub" flange. The purpose is to transfer the pressure of the pipeline, thereby reducing the high stress concentration in the flange base. Neck flange welding is the best design for butt welding those flanges that are provided due to their inherent structural value. However, the price is relatively high because the production process of the product is complicated.
Threaded (threaded) flange: The threaded flange is connected by threaded fasteners. 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 flange: The sliding flange has a lower hub because the pipe enters the single flange before welding. It is welded inside and outside to provide enough strength to prevent leakage. Sliding flanges are matched with boring pipes with slightly larger outer diameters. They are better than the welding of neck flanges, because the initial cost is lower for many users, but the final installation cost is probably not low, because the number of welded neck flanges is less.
Lap flange: The lap flange is actually exactly the same sliding flange, unless it is a radius between the hole and the flange race. It is necessary for the radius to have the flange to accommodate the end of the lap stub. Usually, the lap flange and the lap stub end mating together will assemble the system. The socket welding flange is a similar sliding flange, unless it has a hole and reverse hole size. The matching of the counter hole and the pipe allows the pipe to be inserted into a sliding flange similar to the flange. The diameter of the smaller hole is matched with the same pipe with the same ID. The restriction is a built-in hole that stays at the bottom as a shoulder sleeve designed for pipes. This eliminates any flow restrictions when using socket welding flanges.