What is the difference between a butt-weld neck flange and a flat-weld neck flange?

There are two types of neck flanges: butt-weld neck flange and flat-weld neck flange. There are some differences between them. So what is the difference between a butt-weld neck flange and a flat-weld neck flange? Let's find out.

Introduction to butt-weld neck flange and flat-weld neck flange

1. A butt-weld neck flange refers to a flange with a tapered neck and butt-welded to a cylinder or pipe, which is an integrated flange.

2. The full name of the flat-weld neck flange is a flat-weld neck steel pipe flange, which is a flange that can extend steel pipes and pipe fittings into the flange and connect them to equipment or pipelines through fillet welds.

The difference between a butt-weld neck flange and a flat-weld neck flange

1. Different weld forms:

The weld of a butt-weld neck flange can be inspected by radiography, while that of a flat-weld neck flange cannot. The welding form between a butt-weld neck flange and a pipe is a girth weld, while the welding form between a flat-weld neck flange and a pipe is a fillet weld. Butt welding is a butt ring weld, and flat welding is two corner ring welds. The difference between the two is that the weld between the neck butt welding flange and the pipe belongs to the B-type seam, while the weld between the neck flat welding flange and the pipe belongs to the C-type seam.

2. Different materials:

The material of the neck butt welding flange is usually made of forged steel parts through machining. The material of the neck flat welding flange is made of ordinary steel plates with thickness that meets the requirements through machining.

3. Different nominal pressures:

The nominal pressure of the neck butt welding flange is 1-25MPa, which is a higher level. 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 also be slightly lower.