SO neck flat welding flange and WN neck butt welding flange require welding process qualification
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SO flat welding flange with diameter and WN butt welding flange with neck have different welding seam forms. The welds of necked butt welding flanges can be radiographed, but necked flat welding flanges cannot. The welding form of the neck butt welding flange and the pipe is a girth weld, while the welding form of the flat welding flange and the pipe is a fillet weld. Butt welding is a butt girth weld, and flat welding is two fillet girth welds. The difference between the two is that the weld connecting the necked butt welding flange to the pipe belongs to Class B seam, while the weld connecting the necked flat welding flange to the pipe belongs to Class C seam. The materials are different. Neck butt weld flanges are usually made of forged steel by machining. The neck flat welding flange is made of ordinary steel plates with a thickness that meets the requirements through machining. Nominal pressures vary. The nominal pressure of the necked butt welding flange is 1-25MPa, which is higher. The nominal pressure of the neck flat welding flange is 0.6-4MPa. Compared with the neck butt welding flange, its pressure level is relatively low, and its ability to adapt to pressure will be slightly lower.
None of this has anything to do with welding procedure qualification.
Neck flat weld flanges may also be machined from forgings.
Because the welding surface of the flat welding flange and the pipe has a groove, the weld form is a combined weld.
What is the difference between SO flange and SW flange? It seems that foreigners prefer the use of SW flange compared to SO.
I don't understand what the poster meant :)
The stiffness of the butt welding flange with neck is greater than that of the flat welding flange with neck. It has high strength and is not prone to leakage.
:victory: great post, great collection* Yes, boss
I don’t understand. The welds of pressure parts of pressure vessels must have welding process qualifications. As for flange welds, welds are Category C and B. The national standard requires this, and the relevant welds of flanges in the ASME standard are all Category C.