Pipe Flange

Pipe flange is a disc, collar or ring that attaches to pipe with the purpose of providing increased support for strength, blocking off a pipeline or implementing the attachment of more items. They are usually welded or screwed to the pipe end and are connected with bolts.

A gasket (sealing) is inserted between the two mating flanges to provide a tighter seal. These flanges are either custom with dimensions provided by the customer or they are manufactured according to published specifications.

Several organizations and associations have published specifications that provide dimensional information as well as pressure specifications at different temperatures.

Types of Pipe Flanges

Following are the most common flange types

  • Weld-Neck
  • Slip-on
  • Lap-joint
  • Threaded
  • Blind
  • Socket-weld
  • Orifice Flanges
  • Expander Flange
  • Spectacle Flange
  • Reducing flanges
  • Weldoflange and Nipoflange

Weld Neck Flange

A weld neck flange is a type of flange. There are two designs. The regular type is used with pipes. The long type is unsuitable for pipes and is used in process plant. A weld neck flange consists of a circular fitting with a protruding rim around the circumference.

Slip On Flange

Slip on Flange is essentially a ring that is placed over the pipe end, with the flange face extending from the end of the pipe by enough distance to apply a weld bead on the inside diameter. The OD of slip on flange is also welded on the back side of the flange.

Lap Joint Pipe Flanges

Lap joint pipe flanges slide directly over the pipe and are most commonly used with stub end fittings. A pipe is usually welded to the Stub End and the Lap Joint pipe flange is free to rotate around the stub end. The benefit of this is that there will not be any issues with bolt hole alignment. Lap Joint pipe flanges are often used for applications that require frequent dismantling.

Threaded Flanges

Threaded Flanges are also known as screwed flange, and it is having a thread inside the flange bore which fits on the pipe with matching male thread on the pipe.
This type of joint connection is Speedy and simple but not suitable for high pressure and temperature applications. Threaded Flanges are mostly used in utility services such as air and water.
Threaded (Screwed) flange is similar to the Slip-On flange, but the bore is threaded. Its chief merit is that it can be assembled without welding, explaining its use in low pressure services at ordinary atmospheric temperatures, and in highly explosive areas where welding create a hazard.

Blind flange

A blind flange is a solid flange as shown below. The purpose of these is to block off a section of pipe or a nozzle on a vessel that is not used. (A nozzle is typically a pipe coming out of a vessel and is usually flanged so it can be connected to valves or piping).

Socket Weld Flange

Socket Weld Pipe Flanges. Socket-weld pipe flanges are typically used on smaller sizes of high pressure pipes. These pipe flanges are attached by inserting the pipe into the socket end and applying fillet weld around the top.Socket Weld pipe flanges are typically provided with a raised face, flat face, or RTJ facing.

Orifice Flanges

Orifice flange for run installation should be so constructed, machined and attached to the that the inner surface of the passage extends through the orifice flange so that there is no recess at the orifice plate.

Orifice flanges are used instead of the standard pipe flanges when orifice plate or flow nozzle is used. The basic purpose for this is to measuring the flow rate of either gases or liquids in the respective pipeline.
These flanges are used in various industrial applications and are available in various sizes and materials

Expander Flange

An Expander Flange is a type of welding neck pipe flange used to increase pipe size at the flange connection.
The Expander Flange is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange.
An Expander Flange is a type of welding neck pipe flange used to increase pipe size at the flange connection. Expander flanges are also known as a cost effective alternative to using a separate reducer-welding neck flange combination.

Applications Of Expander Flanges

The expander flange can be used to connect pipe to pumps, compressors and Valves.
Expander Flanges are used in Chemical and petrochemical processing.
Expander Flanges are used in electronics. Expander Flanges are used in processing equipment for maintaining product purity in handling foods, synthetic fibers.
Expander Flanges are used in marine and offshore engineering.
The expander flange is available in a range of sizes and materials.

Spectacle Flange

Spectacle Flange, also called (blind flange) is a pressure-retaining plate with one solid end and one open end connected with a tie bar.

A spectacle flange is a specialty flange made of two metal discs attached in the middle by a small section of steel. Spectacle flanges get their name because they look like a pair of reading glasses, or spectacles. Spectacle flanges, also known as spectacle blind flanges, are most commonly used on piping systems that need to be separated regularly or where the flow through the systems is regularly stopped. One end of the spectacle flange is solid, while the other end has a hole in the center. The spectacle flange can be rotated to place either the solid or hollow end within the pipe system, thereby opening or closing the flow.
For pipe Flanges-regularly seperated for isolation, maintenance or reasons, a spectacle extrudes Solution. Typically, spec blinds was mounted in the open position so-your flow pipe operates and is normally.

Reducing Flanges

Reducing flanges are designed for when there is a change in the pipe size. The predominate flange (dimensions) matching the larger pipe size (NPT) but having a smaller bore matching the smaller pipe size (NPT). These flanges normally come in blind, slip-on, threaded and weld neck flanges.
Reducing Flanges are mostly used in mostly in high pressure Gas and Steam lines.

Weldoflange, Nipoflange

The Weldoflange and Nipoflange is a combination of a Welding Neck flange and a supposedly Weldolet or Nipolet.

About Zaighum Shah 90 Articles
Zaighum Shah is a mechanical engineer having more than 20 years of experience. Zaighum is specializing in product development in Sugar Mill industries. Zaighum has gone through all phases of mechanical engineering and it’s practical implementation. Zaighum has been solving most complex problems, designing new systems and improving existing models and systems.