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Pipe Flanges

7/19/2012 7:54:47 AM | by Anonymous


Piping systems can be formed by using flanges to connect pipes, valves, pumps and other equipment. A flange is an extension of a structure that usually has holes drilled into it. The holes are used to accommodate securing bolts and flanges can seal or join various parts of structures which provide for easy access to disassemble the pipe system for cleaning, inspection or modification. They are able to secure different parts together through welding or screws. Flange joints are made by bolting together flanges with a gasket placed between them to provide a seal. There are several types of flanges available in the market today which can be used for different purposes.


Welding Neck Flange

These flanges are easily recognizable as they have a long tapered hub which fits over the wall thickness from a pipe or fitting. Since the bores of the pipe and the flange match, it is able to reduce turbulence and erosion inside the pipe and the tapered hub of the flange provides an important reinforcement for use in applications that involve high pressures and sub-zero or elevated temperatures. The taper which provides the flange with a smooth transition from its thickness to the fitting or pipe thickness is highly beneficial in conditions where there can be repeated bending that can be caused by variable forces. The perfect fit that the flange provides allows no restriction for product flow. Another advantage of the tapered shape is that it allows for stress to be distributed evenly and allows for easy detection of flaws. These flanges are favored over others in critical applications.


Slip on Flange

The strength that slip on flanges provides is two-thirds that of welding neck flanges and its life under stress and fatigue is one-third that of welding neck flanges. These flanges are easy to use in fabricate applications as they are simply slipped over the pipe which needs to be connected and then a fillet weld is used to run around the end of the pipe to fuse the pipe to the inside of the bore of the flange. The same is done again but to the back end of the flange hub which fuses it to the outside of the pipe. The flange is slipped onto the pipe in a way so that the end of the pipe is just inside the flange and a few millimeters away from the flange face to avoid damaging the flange during welding. These are the most common welding flanges.


Threaded Flange

These flanges can be either referred to as threaded or screwed and are used to connect other threaded and components in non-critical applications and low pressure. The main advantage of these flanges is that no welding is required to weld them to pipes. Despite the fact that they are available in most sizes and pressure rating, these flanges are mostly used in smaller pipes. Threaded flanges can also be used in conjunction with seal welds. However, they should not be used with pipe systems that have thin wall thickness as the cutting of the thread on thin pipes is not possible. Therefore thicker wall thickness pipes are used.


Ring Type Joint

This method is used to ensure that there is a leak proof flange connection at high pressures. A metal ring is compressed into a hexagonal grove which is inserted on the face of the flange making the seal. This method can also be used in conjunction with weld neck, slip-on and blind flanges.



There are several types of flanges which can not only be used for piping but other manufacturing processes as well. Each category has several different types of flanges which serve different roles to provide desired results.

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