What is flange?
A flange is a
method of connecting pipes, valves, pumps and other equipment to form a piping
system. It also provides easy access for cleaning, inspection or modification.
Flanges are usually welded or screwed. Flanged joints are made by bolting
together two flanges with a gasket between them to provide a seal.
Types of Flanges
·
Welding Neck Flange
Weld neck pipe flanges
attach to the pipe by welding the pipe to the neck of the pipe flange. It allows
for the transfer of stress from the weld neck pipe flanges to the pipe itself.
This also reduces high stress concentration at the base of the hub of the weld
neck pipe flanges. Weld neck pipe flanges are often used for high pressure
applications. The inside diameter of a weld neck pipe flange is machined to
match the inside diameter of the pipe. Weld Neck Pipe flanges with a hub have
published specifications that range from 1/2" thru 96". Weld
neck pipe flanges are typically provided with a raised face, flat face, or RTJ
facing. When a raised face is necessary for weld neck pipe flanges, the standard
height is 1/16" for weld neck pipe flanges fewer than 400#. For weld neck
pipe flanges of 400# and up, the standard weld neck pipe flange raised face
height is 1/4".
·
Slip On Flange
These are type of flanges that slide over
the end of piping and then welded in place. These flanges are ideal for lower
pressure applications. These are easily fitted and welded into different pipes.
Welding reduces fabrication costs of these pipes.
·
Socket Weld Flange
Socket
welding flange, a popular type of pipe flange, was initially developed for use
on small-sized high- pressure piping. The fabrication of this type of flange is
similar to that of a slip-on flange. However, the internal pocket of a socket
weld flange allows for a smooth bore and better fluid flow. When provided with
an internal weld, the static strength of this flange is equal to slip-on flange,
but the fatigue strength is 50% greater than double welding slip-on flanges.
Smooth bore conditions in such a flange can easily be attained without having
to bevel the flange face and, after welding, to reface the socket weld flange
as would be required with slip-on flanges. For this reason, the internally
welded flange is popular in chemical process piping.
·
Lap Joint Flange
The
lapped flanges are widely used in steel plants, sugar mills & distilleries,
pumps and petrochemicals, cement and construction industries.
·
Threaded Flange
They are the special type of pipe flanges
which can be attached to the pipe without welding. Threaded flanges are
threaded in the bore which match an external thread on the pipe. These threads
are tapered in order to create a seal between the threaded flange and the pipe
as the tapers approach the same diameter.
·
Blind Flange
A blind flange is used to close ends of
piping systems. It is a kind of round plate with no center hold but with all
the proper bolt holes.
·
Purpose
of Orifice Flanges
Orifice
Flanges are used with orifice plate or flow nozzle for the
purpose of measuring the flow rate of either liquids or gases in the respective
pipeline. Orifice flanges generally come with either raised faces or RTJ
(Ring Type Joint) facings.
