Butt welding flange, also known as Raised Face Weld Neck, is a kind of pipe fitting, which refers to the flange with neck and transition of round pipe and butt welding with pipe.Butt welding flanges are not easy to deform, have good sealing, and are widely used.
They are suitable for pipelines with large fluctuations in pressure or temperature or high temperature, high pressure and low temperature pipelines. The advantage is that the price is relatively cheap, and the nominal pressure does not exceed 2.5MPa; it is also used for transportation prices On pipelines with expensive, flammable and explosive media, the nominal pressure is around PN16MPa.
The significance of butt welding flange
Flange classification
1.Butt welding flange: neck flange welding is usually called "high hub" flange. The purpose is to transfer the pressure of the pipeline, thereby reducing the high stress concentration in the flange base. Neck flange welding is the best design for butt welding flanges that are currently provided due to their inherent structural value. This is expensive because of the design.
2.Threaded (threaded) flange:The threaded flange is connected by threaded fasteners. But the center of the product has a thread size corresponding to the pipe. Its main advantage is that it can be assembled without welding.
3.Sliding flange: The sliding flange has a lower hub because the pipe enters the single flange before welding. It is welded inside and outside to provide enough strength to prevent leakage. Sliding flanges are matched with boring pipes with slightly larger outer diameters. They are better than the welding of neck flanges, because the initial cost is lower for many users, but the final installation cost is probably 4.Lap flange: The lap flange is actually exactly the same sliding flange, unless it is a radius between the hole and the flange race. It is necessary for the radius to have the flange to accommodate the end of the lap stub. Usually, the lap flange and the lap stub end mating together will assemble the system. The socket welding flange is a similar sliding flange, unless it has a hole and reverse hole size. The counter hole is slightly beer than the O.D. pipe matching, so that the pipe is inserted into the flange similar to the sliding flange. The diameter of the smaller hole is matched with the same pipe with the same ID. The restriction is a built-in hole that stays at the bottom as a shoulder sleeve designed for pipes. This eliminates any flow restrictions when using socket welding flanges.
5.Butt welding flange: neck flange welding is generally called "high tie" flange. The intention is to carry the pressure of the pipeline and then reduce the high stress concentration in the flange base. Neck flange welding is the best description of butt welding those currently supplied flanges due to their structural value. This is valuable due to the depiction.
The butt-welded flange has the same pipe diameter and wall thickness as the pipe to be welded, and it is welded just like two pipes. The flat-welded flange is a concave platform that is slightly larger than the outer diameter of the pipe at the interface, and the pipe is inserted and welded. Butt welding has better welding performance and less corrosion. Flat welding and butt welding are the welding methods when flanges and pipelines are connected. When flat welding flanges are welded, only one-sided welding is required. The internal ports of the welding pipeline and flange connections are not required. The welding installation of butt welding flanges requires flanges. Surface welding. Therefore, flat welding flanges are generally used for low and medium pressure pipelines, butt welding flanges are used for connecting medium and high pressure pipelines. Butt welding flanges are generally at least PN2.5MPa. Butt welding is used to reduce stress concentration. Butt welding flanges are mostly neck flanges, also called nipple flanges. Therefore, the installation cost, labor cost and auxiliary material cost of the butt welding flange are higher because of one more process. Not all butt-welding flanges need to be welded on both sides of the inside and outside. There is no special requirement and generally only one weld on the outside. Have you never seen a 1/2" butt-welding flange:), flat welding is better Well, because the pipe and the flange are perpendicular to each other, the pipe will not be inclined.
The shielding gas pressure of the butt welding flange, in order to prevent micro leakage of the butt welding flange, the shielding gas in the furnace should be connected to a certain positive pressure, assuming it is a hydrogen shielding gas, the general requirement is greater than 20kbar. Annealing air and butt welding flanges generally use pure hydrogen as the annealing air, and the air purity is greater than 99.99%. Assuming that the other part of the air is an inert gas, the purity can also be lower, but it cannot contain too much oxygen and water vapor.
Has the annealing temperature of butt welded flanges reached the specified temperature?
Butt welded flanges generally adopt solution heat treatment, usually called annealing. The planned temperature is 1040～1120℃. It can also be inspected through the flaw detection hole of the annealing furnace. The flange pipe in the annealing zone should be an incandescent lamp, but it should not be softened or sag.
Do you know the exact installation sequence of the butt-welded flange? Now, the technical staff of the butt-welded flange manufacturer will explain it to you. I hope it will help you.
First, clean up the inner and outer sides of the connected stainless steel pipe fittings before connecting the butt welding flanges.
Install flanges with grooved rings on the pipes that need to be connected. The port of the pipe needs to be processed with a 90-degree flanging process. After the treatment, the port surface of the pipe needs to be polished. After polishing, it should be vertical and flat, and there are no doubts about burrs, bumps and deformations, and the nozzle needs to be rounded with a special tool. There is also a simple method that is equivalent to using the finished short tube with flanging and then welding it on the tube.
Embed the stainless steel seal ring with O-shaped rubber seal on both sides in the flange with groove ring. The inner hole of the sealing ring is the same as the inner diameter of the pipe. Then connect the flange holes with bolts, and the bolt components need to be tightened symmetrically. When tightening the butt-welded flange, pay attention to the tightness of each joint and meet the required specifications.
