Weld Neck Flange

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RFWN Flanges (Raised Face Weld Neck Flange) are one of the most commonly used flanges in the piping industry. They are easy to recognize with their long tapered hub that is matched to the wall thickness (bore) of the pipe.

Weld neck flange and long weld neck flange provide reinforcement in applications requiring high pressure and during low and high pressure extremes. It also helps in low cycle fatigue caused by line expansion of other variable forces.

Weld neck flange bore is machined to match the ID of the pipe or fitting. This creates a smooth transition to and from the weld neck flange and prevents turbulence at the welding neck. Hence, it is important to specify the pipe schedule at the time of buying a weld neck flange. Weld neck flange is welded to pipe with full penetration weld and provides excellent stress distribution through a tapered neck. Weld is also routinely radiographed or UT examined in critical applications.

Weld neck flange is available in both raised face and flat face configuration. Most common weld neck flanges have standard bore or extra heavy bore. Sch 120 or Sch 160 bore flanges in heavier weights such as 600# to 1500# are also common in weld neck flanges. 

Trupply sells all kinds of weld neck flanges in A105, A105N, Stainless Steel, Duplex and Super Duplex Steels and Nickel Alloys. Shop online or call us for your custom flange quote!

The video below gives an overview of Weld Neck Flange

Video Transcript:

This is a weld neck flange. This is a very popular flange, a lot of people use it. Again, as the name says, it has a welding neck right here. 150 pound flange has four bolts, raised face, a little lip on the backside, and the stamping on the side. The way the weld neck flange is used is you take a pipe (this is a 2 inch pipe) and you have to have a bevel. This does not have a bevel, but if you are installing, you’ll have a bevel, and then you just butt it up right like this and then you make a weld. That’s how it is installed and it’s called a weld neck, this is a welding neck.

On the weld neck also, you have to specify the bore. So, if you specify the schedule, whether it’s for schedule 40, schedule 80 and so on, that will determine the size of the bore here. Once you have welded it, you don’t want your pipe to be thicker than the flange; that will not be good for the flow. Once you specify the right schedule of the flange that matches the schedule of the pipe, if you look from the inside, you won’t be able to see any edges sticking out. A weld neck flange.