Long Weld Neck Flanges
Welding Neck Flanges (RFWN Flange) are easy to recognize. They include a long tapered hub that gradually meets the wall thickness from the pipe or fitting. The long tapered hub provides an important reinforcement for use in several applications involving high pressure, sub-zero and / or elevated temperatures. In conditions of repeated bending, caused by line expansion or other variable forces, the smooth transition from flange thickness to pipe or fitting wall thickness is extremely beneficial. These flanges are bored to match the inside diameter of the mating pipe or fitting so there will be no restriction of product flow. This prevents turbulence at the joint and reduces erosion. They also provide excellent stress distribution through the tapered hub and are easily radiographed for flaw detection. This flange type will be welded to a pipe or fitting with a single full penetration, V weld (Buttweld).
A105 - The standard forged carbon steel piping components for ambient and high temperature / pressure systems
SS304 - A common standard for stainless steel due to its malleability, high corrosive resistance weld-ability
SS316 - A molybdenum stainless steel that provides excellent tensile, creep and stress-rupture strengths at elevated temperatures
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, it has four bolts, again, raised face, it has a little lip on the backside, the stamping on the side. The way the weld neck flange is used is you take a pipe, again, 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. Again, this is also, that once you weld 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, it will be almost... You won’t be able to see any edge sticking out. A weld neck flange.