The calculated strength from a Slip On flange under internal pressure is of the order of two-thirds that of Welding Neck flanges, and their life under fatigue is about one-third that of the latter. The connection with the pipe is done with 2 fillet welds, as well at the outside as also on the inside of the flange. A combination of flange and elbow or flange and tee is not possible because named fittings have not a straight end, that complete slid in the Slip On flange.
