Flange Types

Flange valves Type
The purpose of a flange is simply to join two pieces of pipe or connect up valves in a piping system. It may be cast, forged, or a ring of steel cut from plate. Generally flanges are manufactured in pressure classes of 150, 300, 400, 600, 900, 1500 and 2500 lbs.

Facing
One of the most important parts of the flange is the facing. Here are the most commonly used facings:

Flat Face	Raised Face	Ring Type Facing

Standard Flange Designs

Threaded - The bore of this flange is threaded to match the pipe size. Usage: Low pressure systems and where welding could be hazardous.	Lap Joint - Bored slightly larger than the OD of the pipe, the radius on the bottom matches the radius on the stub end. It is slipped over the pipe and a stub end is welded onto the pipe. The flange is then slipped over the stub end and bolted up. Usage: For systems that need frequent cleaning and/or inspection.	Welding Neck - Bored to the ID of the pipe and has a high neck to which pipe is welded. Probably the best welding flange available because of its high, heavy neck. Usage: Wherever a sound welded joint connection is needed.
Blind - As the name indicates, this flange is a solid circle drilled to match a companion flange. Usage: To shut off or blank off piping.	Slip-On - Has a low hub and is bored slightly larger than the OD of the pipe. This flange is welded on both inside and outside of the flange face to prevent leakage.Usage: Used in lieu of welding necks when cost or space is a major consideration.	Socket Weld - The socket weld flange is bored to the ID of the pipe and counter bored slightly larger than the OD of the pipe to allow the pipe to be inserted and welded in place. Usage: 4" and smaller high pressure systems.