Different Types Of Pipe Flanges In The UK And Their Uses
When it comes to pipe flanges in the UK, there is a wide variety of choices. The most common types of pipe flanges are blind, slip-on, lap joint, weld neck, threaded, long welding neck, and socket weld flanges. Apart from these standard types of flanges, there are also special flanges that exist such as orifice, swivel, reducer, and expander flanges.
When using a flange for a piping application, it largely depends on the required strength for the flanged joint. As an alternative to welded connections, pipe flanges are used to facilitate maintenance operations as a flanged joint is able to be quickly and conveniently dismantled.
Here is a brief explanation of the most common types of pipe flanges:
Slip-on flanges
This type of pipe flange is connected to the fittings or pipe itself by two fillet welds. One is on the outside of the cavity of the flange and the other is on the inside. A slip-on flange’s bore size is larger than the outside diameter of the connecting pipe.
This is because to be connected by a fillet weld, the connecting pipe needs to slide inside the flange. Slip-on flanges (also known as hubbed flanges) are very easy to recognise because of their compact and slim shape.
Welding neck flanges
This type of flange can be welded with a pipe by its distinct long tapered hub. Welding neck flanges are typically used for applications involving high pressure and low or high temperatures which require an unrestricted flow of fluid, gas, or air through the piping system.
Because of the absence of pressure drops, it prevents negative effects such as corrosion, erosion, and turbulence of the metals within close proximity of the flanged joints. Its tapered hub allows for the smooth distribution of mechanical stress between the pipe flange and the pipe. It also allows for easier radiographic inspections to detect potential welding defects and leakages.
Threaded flanges
This type of flange is joined to a pipe by screwing the flange onto the pipe without the need for seam welds. However, small welds can be applied if needing to increase the strength of the connection. Threaded flanges are available in a variety of different pressure ratings and sizes. They are mostly used in small-sized piping applications involving low temperatures and low pressures.
Lap joint flanges
These types of pipe flanges in the UK are always used in conjunction with a stub end and have a flat face. It sits on the back of the stub end by slipping over the pipe. Both are kept together through the pressure of the bolts.
Lap joint flanges are used with stub ends as a cost-effective solution when using nickel alloy or stainless steel pipelines because the flange’s material can be of a lower grade than the stub end material.
Long weld neck flanges
This type of flange is similar to weld neck flanges, but with the exception that the tapered hub acts as a boring extension due to being extended. Long weld neck flanges are typically used on barrels, columns, and vessels. They are also available in the equal barrel and heavy barrel types.
Socket weld flanges
This type of pipe flange is connected to a pipe with a single fillet weld that is on the outer side of the flange. It is similar to a slip-on flange which requires two fillet welds. To connect a socket weld flange to a pipe, the pipe needs to be inserted first into the socket of the flange. Once it has reached the bottom of the flange, it is then lifted around 1.6mm before being welded.
The gap created is to allow room for proper positioning of the pipe that is inside the flange socket once the welding has finished. This type of flange is generally used for high-pressure and small-sized piping.
However, socket weld flanges are susceptible to corrosion in the area between the shoulder of the socket and the end of the pipe. Socket weld flanges have a similar static strength to slip-on flanges but have a higher fatigue strength as a result of having a single fillet weld instead of a double.
Blind flanges
Unlike the other types of flanges mentioned, blind flanges are solid in the middle and don’t have a centre hole. They are typically used to seal or blind a pipeline and block the flow of liquid or air. Blind flanges can withstand a large amount of mechanical stress due to the required bolting forces and system pressure. They allow easy access to the pipeline because they are to be easily unbolted. Blind flanges are also much easier to manufacture.
Make sure you are using the best pipe flanges in UK by searching online for a leading pipework systems manufacturer that can offer a wide range of pipes, flanges, pipe components, pipe segments, and much more.
