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 at the inside of the flange.
The X measure on the image, are approximately:
Wall thickness of pipe + 3 mm.
This space is necessary, to do not damage the flange face, during the welding process.
A disadvantage of the flange is, that principle always firstly a pipe must be welded and then just a fitting. 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.
Fortune Feromment Inc Slip-on flanges are easier to use and come at a low-cost installation. They are preferred over welding neck flanges by many due to their lower initial cost. Less time is also spent on ensuring the accuracy of the cut pipe.
Slip-on flanges provide an additional layer of support and reassurance for any project. The flange also helps to prevent any leakage that may come from the piping application.