Flange is a sealing component composed of flange, sealing gasket and fastening bolt. It plays an important role in connecting tubes, pumps, valves, pressure vessels and various pressure-bearing equipment. It is an important part of machinery, petroleum, It is the most widely used pipe connector in pipeline systems and devices in chemical, petrochemical, water conservancy, electric power, light industry, textile, shipbuilding, pharmaceutical and nuclear industries. According to statistics, in the petrochemical industry, there are more than 200,000 flange sealing joints in a large refinery alone, which is enough to prove that the use of flange is very large.The flange is both a detachable connector and a pressure-bearing seal. It mainly uses connecting bolts to pass through the flange bolt holes, and exerts force on the flange sealing surface under the action of the applied bolt pre-tightening force. Compression force compresses the sealing gasket clamped between a pair of Flanges, causing the gasket to undergo plastic deformation or elastic deformation under the action of the bolt compression force, thus filling the micro-geometric gap of the flange sealing surface. Sealing purpose.
The sealing failure of flange mainly manifests itself as leakage. In pipeline systems and devices in various industries, the failure of flange seals can cause a large amount of waste of energy and Raw Materials at least, or lead to equipment scrapping, production shutdown, casualties and serious environmental pollution. Therefore, modern petroleum, chemical, petrochemical, atomic energy, aerospace and other industries have put forward more stringent requirements for the sealing of pipeline devices.
As a unit of the flange joint, the flange usually appears as an independent standard part. Flange elements are generally standardized.
In GB/T9112-2010 "Steel Pipe Flange Types and Parameters", the flange types and codes of two different flange systems are specified:
One is the flange type and code with the nominal pressure marked with PN (European flange system);
The other is the flange type and code marked with Class for the nominal pressure (American flange system).
Flanges’ type | French code for PN mark (European standard) | Flange code for Class mark (US standard) |
Integral flange | IF | |
Threaded flange | Th | |
Flange with neck butt welding | WN | |
Flat welded flange with neck | SO | |
Socket welding flange | SW | |
Flat welded flange | PL | |
Type A butt welded ring plate loose sleeve flange | PL/W-A | |
Type B butt welded ring plate loose sleeve flange | PL/W-B | |
Flat welded ring plate loose sleeve flange | PL/C | |
Tube end flanging plate loose sleeve flange (Type A) | PL/P-A | |
Flanged sub plate loose sleeve flange (Type B) | PL/P-B | |
Butt welded ring loose sleeve flange | PJ/SE | LF/SE |
Flat welded ring loose sleeve flange | PJ/RJ | |
Butt welded ring with neck loose sleeve flange | HL/W | |
Long high neck flange | LWN | |
Flange cover | BL | |
Lined flange cover | BL(S) |
Sealing surface form | designation | EN standard code | ||
plane | FF | A | ||
surfacing | RF | B | ||
Concavo-convex surface | convexity | MF | M | E |
Concave surface | F | F | ||
Tongue and groove face | tongue face | TG | T | C |
groove face | G | D | ||
An O-ring | O-ring convex surface | OSG | OS | G |
O-ring groove surface | OG | H | ||
Ring joint | RJ |
Nominal size is a basic parameter of the pipe element and the main parameter of the flange. In the flange marked with PN, its nominal size code is denoted by DN; In flanges marked with Class, their nominal size codes are denoted by NPS and DN.