Flange, Socket Weld

Socket weld flange simplified as SW flange, it has a recessed area (like a shoulder) in the flange bore, this shoulder serves as a guide to set the depth of the pipe that inserted to the flange. Socket welding flange initially designed for high pressure small diameters piping system.
How to Use
Insert the pipe end into socket weld flange, until the pipe bottom touch the shoulder area, pull back 1.6mm (1/16”) distance of the inserted pipe then do fillet welding. The point is to create a expansion gap (1 fillet weld) between the flange and the pipes or fittings.

How is Socket Welding Flange Generated
The socket welding flange was firstly to use for stainless steel superheater, due to avoid cracking defects caused by thermal stresses in heating processes, and after years development it became a standard applications for all types of material.
Advantages
Socket weld flange could replace threaded flange, to minimize the risky of leakage.
No need to beveling before welding.
Welding work outside of the pipe, will not penetrate the pipe bore
It is recommended for applications where internal welding operations are particularly difficult. This sock welded construction eliminates internal pockets while avoiding warpage of welding heat and damage to the flange face caused by weld spatter. It has the same internal pressure as the sliding on the flange, and has a better fatigue life.
Disadvantages:
Socket welded flange requires higher skills for welder, which the welding need to make sure that the expanding gap between the pipe and shoulder is 1/16 inch.
The expansion gap create the chances for the crack defects, especially for anti corrosive pipes as stainless steel pipes, so the cracks between the pipe and flange will cause the corrosive problems. So SW flange will not be compatible with corrosive or radioactive environment, as this solid buildup at the joint can cause operational and maintenance problems. So that’s why people use but welding more often as the welding completely through the pipe from outside to inside, which makes the connects more strong and anti corrosive.