Dimentional Standards for Flange
ASME B 16.5 :Upto 24 inch
Dimentional STandard for Large Flange
ASME B 16.47 : Above 24 inch
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. Flanges are available in round, square, and rectangular shapes. In some cases, flanges are usually in the shape of a ring or a plate to form a rim at the end of a pipe when fastened to the pipe.
TYPES OF FLANGES
MATERIALS FOR FLANGES
The most common materials used in flanges produced is carbon steel, stainless steel, cast iron, aluminium, brass, bronze, plastic etc.
In addition, flanges, like fittings and pipes, for specific purposes sometimes internally equipped with layers of materials of a completely different quality as the flanges themselves, which are "lined flanges". The material of a flange, is basically set during the choice of the pipe, in most cases, a flange is of the same material as the pipe.
SOME COMMON FLANGE MATERIALS 1. ANSI FLANGES
Size : 1/2" TO 54"
Pressure Rating : 150#, 300#, 600#, 900#, 1500#, 2500#
Carbon Steel : A-105, A-350 LF2, etc.
Alloy Steel : F-5, F-9, F-11, F-22, F-91, ETC.
Stainless Steel : SS 304, SS 304L SS316,
SS 316L, SS 316Ti, SS 321, SS 347, SS 304H, 317L, Etc.
Duplex SS : F-51, F-55
High Strength Steel : A694 Gr 52, 60, 65, 70,
AISI 4130, 4140 Nickel Alloys : Monel 400, Inconel 625, Inconel 825, Alloy 20, etc.
Standards : ASME B 16.5, ASME B 16.47, API 6A
Type : SORF, WNRF, SWRF, BLRF, Threaded etc
Specials : Spacers, Spectacle Blinds, Drip Rings, RTJ, Tongue, Groove, Orifice, etc.
2. DIN B.S. & UNI FLANGES
Size : DN 10 to DN 800
Pressure Rating : PN6 to PN64
Material : 1.4404, 1.4307, 1.4571, 1.4541, 1.4462, 1.4306
Standards : EN 1092-1, BS 4504, UN 2278 etc.
Type : SORF, WNRF, BLRF, SWRF, Threaded, etc.
Specials : RTJ, Tongue, Groove, Orifice, etc.
Dimentional Standards for Metallic Gasket
ASME B 16.20
Dimentional STandard for Non-Metallic Gasket
ASME B 16.21
Flanged joints are made by bolting together two flanges with a gasket between them to provide a seal. The gasket's function is to seal two different surfaces held together by one of several means, the most common being screw-threaded devices such as bolts.
The charecteristics of Good Gasket
The surface finish of a flange is described as follows:
Dimentional Standards for BOLTS
ASME B 18 . 2 . 1
Dimentional STandard for NUTS
ASME B 18 . 2 . 2
The design of bolt over a nut acts like a spring load.The bolt is a spring. It is an elastic member that has been stretched to develop a load. The more load spring provided by the bolt, the better the retention of stress on the gasket to maintain a leak proof joint. It must not be over-elongated (over-strained), or the elastic limit of the steel will be exceeded. The bolt then deforms and, with continued loading (stressing), may rupture.
To avoid such problems with bolt tightening, the use of a torque wrench is recommended. The equipment designer normally specifies the torque required for a product. This ensures that the maximum available load is applied consistently to the gasket. The load will be better retained by using a bolt with a longer grip, thereby ensuring a leak proof joint.
The Assembly of Flange Gasket and Bolts.
The assembly of flanges, bolts and gaskets form a family. The proper installation of all the three is very important to have perfect leak proof sealing in a flanged joint.Improper installation of the assembly can lead flange leakage which is unsafe .