The form of a socket weld flange is similar to that of a slip-on flange, but it has a counter-bored opening to accommodate pipe. Smaller high pressure pipe diameters are usually fitted with socket welding pipe flanges. A lot of high pressure systems, such steam lines and hydraulic machinery, use socket weld flanges. Fillet weld is applied around the flange hub after the pipe is inserted into the socket end to attach socket weld pipe flanges. This makes it possible for the fluid or gas inside the pipe to flow more smoothly and efficiently. Application of an optional internal weld is possible in high stress scenarios.