Flanges – A Small Guide Book

Flanges are largely used in different fields including water, transport, petroleum, and gas. It also has applications in the areas of chemical fertilizers, power generation, and chemicals. It is often available in a range of types and shapes. Also, diversified steel materials are used in producing flanges which include low carbon steel, stainless steel, high-alloy steel, and non-ferrous steel. So, you can choose any form of any metal according to the fluid type and environment of the service.

A flange is a popular way to connect pipes, pumps, valves and other tools for producing a pumping system. It also allows easy access to modify, inspect and clean. Normally it is screwed or welded. Flanged joined are prepared when two flanges are bolt-together by using a gasket between them that acts as a seal.

Most of the flanges are used in the chemical and petroleum industry, and the most common types of flanges are –

• Slip-on flange

• Welding neck flange

• Lap joint flange

• Socket weld flange

• Blind flange

• Threaded flange

Except for the commonly used flanges, there are a few special standard flanges including –

• Long welding neck flanges

• Orifice flanges

• Expander flange

• Reducing flange

• Nipoflange

Flanges are prepared with a wide range of materials such as cast iron, cast steel, stainless steel, brass, aluminium, plastic, bronze, etc. But among these the most used material is forged carbon steel which has machined surfaces.

Added to that, flanges like pipes and fittings are often remained internally armed with materials layers which are of totally different quality with the flanges. These serve some specific purposes and called lined flanges.

The flange material is chosen according to the choice of the pipe. Mostly, the pipe and the flange contain similar material. If not indicated in prior, all the flanges fall under ASTM or ASME standards. ASTM describes different qualities for materials. ASME B 16.5 defines the dimensions, tolerances for dimensions, etc.

Every ASME B 16.5 flange has multiple standard dimensions. When a customer places an order for a flange, the flanges supplier wants to know the desired quality of the material. For example, A 182 flange is forged stainless steel, while ASTM A 105 flange is forged carbon steel.

There are no standards available that can define whether a flange connection should be used or not. Any newly constructed factory is needed to minimize the number of flange connections because only a weld is required for connecting two pipe pieces. This is cost-saving for the two flanges, the second weld, the stud bolts, the gasket, the second weld NDT cost, etc.

• A new line can be produced in a workshop and it can contain a number of pipe spools.

• Without being welded these pipe spools are eligible to get assembled in the plant.

• NDO is performed in the workshop so it is not necessary within the plant.

• Painting and blasting things have done in the workshop so they need not be performed in the plant again.

Contacting any reputed flanges supplier in the town you can get the desired material and quality for your application.

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