Flanges are classified in two ways based on how they are connected to each other and sealing between them, as well as how they are connected to pipes or other piping components. Types of flanges in terms of connecting to each other and sealing (flange front):
(RAISED FACE FLANGES)
(FLAT FACE FLANGES)
RTJ (RING TYPE JOINT FLANGES)
(MALE AND FEMALE FLANGES)
(TONGUE AND GROOVE FLANGES)
Types of flanges
(RAISED FACE FLANGES)
These types of flanges, which are identified by the abbreviation RF symbol, have a circular upper part in the front part of the flange (on the flange that will be paired with the opposite flange) which, when connected, is a gasket or a sealing gasket. It is placed between the flanges and on that part, and due to the protrusion of this part, the pressure caused by tightening the screws connecting the two flanges, is completely inserted into the protruding part of the two flanges and into the gasket between them, and in this way, a good sealing is done. The surface of the raised part is sometimes smooth, but in most cases, they have concentric circular or spiral grooves (SERRATED FINISH), and the number and depth of these grooves are determined based on the standard. The standard height of the small part of the flange in classes 150 and 300 is about 2 mm and in higher classes it is 7 mm.
(FLAT FACE FLANGES)
These flanges, which are also called flat front flanges or flat face flanges, have a smooth surface in the front part, and usually cast iron flanges or steel flanges made of sheet, which are used in low pressures, are made of this type. According to the standard, when the flat surface flange is to be connected to the carbon steel flanges, the raised surface of the opposite flange should be removed. so that unbalanced pressure is not applied to the flange with a smooth surface from the opposite flange.
RTJ (RING TYPE JOINT)
Ring joint flanges have a depression in their sealing surface, which is filled by a special metal ring washer that is placed between two ring flanges, and sealing is done. The steel material of the sealing ring is softer than the material of the flanges, and when two ring flanges are pressed together by bolts, it is deformed inside the groove and takes the shape of the groove, and in this way, metal to metal sealing is formed. These flanges are used for high temperature and pressure, i.e. class 600 and above and temperatures above 400 degrees Celsius, in which rubber gaskets cannot be used.
RTJ (RING TYPE JOINT)
The male, female and tongue and groove models are designed in such a way that a part of the sealing place of one is placed in the sealing place of the other, and the purchase and use of the flange must be in pairs. Male and female flanges do not have the ability to connect to equipment with a flanged connection, that is why they have a very limited use and are rarely produced, and it can be said that they are obsolete.
Male and female flange
Types of flanges in terms of how to connect to pipes or other components
(WELD NECK FLANGE)
(LONG WELD NECK FLANGE)
(SLIP ON FLANGE)
(SOCKET WELD FLANGE)
(BLIND FLANGE)
(LAP JOINT FLANGE)
(THREADED FLANGE)
(ORIFICE FLANGE)
(SPECTACLE BLINDE / SPADE AND SPACER)
Types of flanges in terms of how to connect to pipes or other components
Welded throat flanges are connected to the pipe by welding. This allows the transfer of stress from the welded flange to the pipe and also reduces the high stress concentration in the throat flange. Weld neck flanges are often used for high pressure applications. One of the characteristics of the welded neck flange is its grade, which indicates the thickness of the edge of the flange wall and its inner diameter, which should be chosen according to the pipe. The edge of the flange throat wall is conical so that it can be connected to the pipe by welding. These flanges are made from size ½ to 24 inches according to ASME-B16.5 standard and in sizes from 26 to 60 inches according to ASME-B16.47 series A and B standard, where A series flanges are thicker, heavier. And they are more resistant than B series.
LWN (LONG WELD NECK FLANGE)
Welded long throat flange, which is abbreviated as LWN, is actually the same as the throat flange, but the length of the throat part is significantly longer. This flange is usually used as a nozzle for barrels or distillation columns. The length of the throat part and other dimensions of these flanges are made according to ASME-B16.5 and ASME-B15.47 standards.
(SLIP ON FLANGE)
Slipon flange or Slipon, which is also known as flat flange, is one of the most widely used types of flanges that is connected to the pipe by welding. The inner diameter of this flange is slightly larger than the outer diameter of the same size pipe, and for connection, the pipe is placed inside it and connected to it from the inside and outside of the flange by welding, and it can be said that it is easy to use and install. Slipon flange is less resistant to pressure, vibrations and fatigue compared to the throat flange, and it is also lower in price, but due to the need for more welding, it may have a higher cost in the project. These flanges are produced based on ASME/ANSI B16.5, BS3293 standards in ½ to 60 inch sizes and RF and FF types.
(SOCKET WELD FLANGE)
Welded silent flange or welded socket flange is one of the types of flanges that are connected to the pipe by welding. This flange has a step in the part where the fluid passes, which divides its inner diameter into two parts; It includes one part that is equal to the inner diameter of the pipe of the same size and class and the other part with a larger diameter that is slightly more than the outer diameter of the pipe of the same size. To connect, the pipe is placed inside the socket part of this flange and goes inside until its step, and then the border between the pipe and the flange is welded and sealed from the outside of the pipe. Silent flanges are manufactured in sizes ½ to 2 inches and in classes 150, 300, 600 and 1500 and based on the ANSI B16.5 standard.
(BLIND FLANGE)
The blind flange is a closed disk-shaped plate that is used at the end of pipeline routes and pressurized routes to temporarily or permanently block the pipe. This type of flange withstands more pressure than other flanges. Blind flanges are produced based on ASME B16.5 and ASME B16.47 standards in different dimensions and in classes 150 to 1500 and based on API standards in classes 2000, 3000, 5000, 10000 and 15000 and in RF, FF and RTJ types. be.
(LAP JOINT FLANGE)
Lap joint flanges are used together with the bottom ring or stub end. For connection, the bottom of the rim is passed through the lap joint flange and welded to the pipe, and the lip joint flange can rotate freely around the stub end. The advantage of this work is that there is no need to worry about adjusting the screw holes and the flange is not in contact with the fluid and only has the task of attaching the bottom of the rim to the opposite flange or the bottom of the opposite rim. Lap joint flanges are often used for applications that require frequent arm closing. The inner diameter of this flange is slightly larger than the outer diameter of the pipe and Stub End of the same size so that the bottom of the rim can be passed through it. The difference between the lap joint flange and the slipon flange is in the forehead part, the lap joint flange does not have a protruding part for connecting the gasket, and the angle between the forehead and its inner part is curved, but in the slipon flange, this part is sharp at 90 degrees and the forehead It may be RF or RTJ.
(THREADED FLANGE)
A threaded flange, which is also called a rib flange, is similar to a slipon flange, except that the inside of the flange has conical threads and is connected to pipes with external threads. The advantage of these flanges is that they can be connected without welding, and they are the best option for situations where welding is not possible due to reasons such as the possibility of explosion. Threaded flanges are often used for small diameters and low pressures.
(ORIFICE FLANGE)
Orifice flange is actually the same as the throated, slipon or threaded flange, with the difference that the rim part of the flange has a hole or holes with NPT thread for installing instruments and gauges for measuring temperature, pressure, etc. .
