SO flange and WN flange cannot be replaced at will. As far as the manufacturing angle is concerned, the SO flange has a large inner diameter, which means that the weight is small and the cost is low. In addition, WN flanges with a nominal diameter greater than 250mm need to be tested, SO flanges do not need to be tested, so the cost is low.

The difference between WN flange and SO flange

1. Different forms of welds: The welds of SO flange cannot be radiographically inspected, while the welds of WN flange can. The welding seam between the SO flange pipe and the flange is a fillet weld, while the welding seam between the WN flange and the pipe is a girth weld; SO flange is two fillet girth welds, and WN flange is a butt girth weld .

The difference between SO flange and PL flange is that SO flange has one more place in the pipeline welding part than PL flange. PL flange is also a flat flange. The boss without flange is also flat fillet weld.

The weld between WN flange and the connection pipe belongs to type B seam, and the weld between SO flange and connection pipe belongs to type C seam, and the non-destructive testing after welding is different.

2. The nominal pressure is different: the nominal pressure of SO flange is: 0.6---4.0MPa, while the nominal pressure of WN flange is: 1--25MPa grade. Obviously, the suitable pressure grade of SO flange is lower.

3. Different connection methods: The biggest difference in structure between SO flange and WN flange is the connection between the pipe and the flange. The SO flange is generally the connection between the pipe and the flange, while the WN flange is the flange and the pipe butt.