A flange is a (usually) disc-shaped piece of equipment used to connect a pipe to a tee, choke, valve or other component to form a pipework system. Forged flanges make access for cleaning, repairs, modification or inspection much easier.
Typically, once a flange has been attached to each end of the pipe or tube to be joined, a gasket is inserted in the middle to form a seal. The flanges are then joined together before being welded or threaded onto the pipe system. This provides both support and strength to the join.
The most common material used for forged flanges is forged carbon steel, but they can also be made from other materials, such as stainless steel, brass, aluminium, cast iron, plastic and bronze, among others. In most cases, the material chosen for the flange will be same as the material used for the pipe or tube.
Types of Flanges
There are six main types of flanges, namely:
Blind Flanges – Also called blanking flanges, these are used to close off pumps, valves or pipelines. They do not have a centre bore, and can be supplied with or without hubs.
Slip-on Flanges – these are the least expensive flanges and have a diameter slightly larger than the pipe or tube, meaning they can easily be slipped directly over the end, before being welded both inside and out to give strength and prevent leaks.
Socket Weld Flanges – most commonly found in high-pressure, smaller pipe applications such as hydraulic and steam lines, these flanges are attached to the pipe by a fillet weld around the hub of the flange. This allows for a much smoother fluid or gas flow through the pipe.
Weld Neck Flanges – often chosen for high-stress applications, these flanges are designed to be joined to a piping system by butt welding. Because their diametre is the same as the inside of the pipe, turbulence and erosion are reduced.
Threaded Pipe Flanges – these are unique in that is no need to weld them to the pipe as they have an outer thread. While this makes them easy to assemble, their uses are limited mainly to small diameter, low pressure applications.
Lap Joint Flanges – easily aligned and assembled, these flanges are best suited to low pressure applications where frequent dismantlement for inspection is required.
Steelmor stocks EN, BS4504, BS10 and SABS 1123 flanges in Grades 304/L and 316/L, and sizes from ½” to 24”. Larger sizes can be made to your unique specifications if required, so why not talk to us today to find out how we can help.