Flanges
General Information
Flanges
A flange is a forged or cast ring designed to connect sections of pipe or join pipe to a pressure vessel, valve, pump or any other integral flanged assembly.
Flanges are joined to each other by bolting and sealed using either a gasket or sealing ring.
They are joined to the piping system by welding or threading.
The basic types of flanges are: slip on, weld neck, threaded, socket weld and swivel/lap.
Available pressure ratings: 150lb, 300lb, 400lb, 600lb, 900lb, 1500lb, 2500lb and 5000lb.
The most common facings machined on flanges are:
- Raised face, 1/16” for 150lb and 300lb,1/4” for 400lb and heavier
- Flat face, for 150lb and 300lb only (other pressure ratings may be flat face on request)
- Ring type joint (available on all pressure ratings)
Slip-On flanges
The flange is slipped over the mating pipe then welded both inside and outside to provide strength and prevent leakage.
This type of flange is normally used in preference to weld neck flanges due to its lower cost and that less accuracy is required when cutting pipes to length.
Weld Neck flanges
Designed to mate with pipework by means of butt welding, more expensive than slip on but preferable in high stress applications.
The flange neck transmits stresses to the pipe thus reducing stress concentrations at the base of the flange.
The flange bore matches the pipe bore reducing turbulence and erosion.
Threaded flanges
Similar in profile to a slip on flange with the bore threaded thus enabling assembly without welding.
Socket Weld flanges
Similar to a slip-on flange with the bore counter-bored to accept the mating pipe, the remaining flange bore matches the pipe bore reducing turbulence and erosion.
Attachment to the pipe is achieved by a fillet weld around the hub of the flange.
Swivel / Lap flanges
Similar in design to a slip-on flange with an added radius at the intersection between flange bore and face. Designed to fit over pipework it is retained in place by a lap stub end, which is buttwelded to the pipework allowing the flange to swivel in position allowing easier assembly to mating flanges.
The stub end incorporates a mating radius to that on the flange and the face on the stub end forms the gasket sealing face of the flange.
The stub end bore matches the pipe bore reducing turbulence and erosion.
SAE J518 Code 61/62
Code 61 – Standard pressure series
Code 62 - High pressure series
This type of connection comprises of an integral hub insert, which incorporates an O ring seal in the hub face. The hub is held in place by means of a backing flange secured by four mounting bolts.
The backing flange can be supplied split (2 halves) for ease of installation.
This type of fitting is available in either straight or elbow configurations.
Flanges
Further Information