General Introduction
The flange is a ring-shaped device designed to be used as an alternative to welding or threading various piping system components used throughout the piping system. Flanged connections are used as an alternative to welding because they can be easily disassembled for shipping, routine inspection, maintenance, or replacement. Flanged connections are preferred over threaded connections because threading large bore pipe is not an economical or reliable operation. The flange is widely utilized in many piping systems. Flanges are primarily used where a connecting or dismantling joint is needed. These joints may include joining pipe to fittings, valves, equipment, or any other integral component within the piping system.
Flange Types
The flanges can be furnished in miscellaneous types including welding neck flange, blind flange, slip on flange, threaded flange, lap joint flange, plate flange, socket welding flange, long welding neck flange, orifice flange, reducing flange, spectacle blind flange, spacer flange, paddle flange, swivel flange, anchor flange, etc.
Pressure Ratings of Flanges
Generally, flanges used in piping system can be categorized in two systems: Metric and US Customary. Forged flanges manufactured to relative ASME standards can be categorized into seven US Customary pressure ratings: Class 150, Class 300, Class 400, Class 600, Class 900, Class 1500, Class 2500. Flanges manufactured to relative EN/BS/DIN standards can be categorized into Metric pressure ratings: PN 2.5, PN 6, PN 10, PN 16, PN25, PN 40, PN 63, PN 100, PN 160, PN 250, PN 320, PN 400. The pressure rating of a flange material is quite temperature-dependent. The maximum allowable pressures of various ferrous and nonferrous metals at maximum applicable temperatures are usually prescribed in each standard.
International Standards for Flanges
- US Standards: ASME B16.5, ASME B16.47, ASME B16.48, ASME B16.36, AWWA C-207, MSS SP 44, API 605, API 6A.
- DIN Standards: DIN 2527, DIN 2573, DIN 2576, DIN 2502, DIN 2503, DIN 2543, DIN 2544, DIN 2545, DIN 2630, DIN 2631, DIN 2632, DIN 2633, DIN 2634, DIN 2635, DIN 2636, DIN 2637, DIN 2638, DIN 2628, DIN 2629, DIN 2627, DIN 2641, DIN 2642, DIN 2652, DIN 2653, DIN 2655, DIN 2656, DIN 2673, DIN 2674, DIN 2675, DIN 2676, DIN 2558, DIN 2561, DIN 2565, DIN 2566, DIN 2567, DIN 2568, DIN 2569, DIN 28115, DIN 86029, DIN 86030.
- BS Standards: BS 4504, BS 10, BS 3293, BS EN 1092-1.
- Italian Standards: UNI 2276, UNI 2277, UNI 2278, UNI 6083, UNI 6084, UNI 2280, UNI 2281, UNI 2282, UNI 2283, UNI 2284, UNI 2253, UNI 2254, UNI 6091, UNI 6092, UNI 6093, UNI 6094, UNI 6095, UNI 6088, UNI 6089, UNI 6090.
- ISO Standards: ISO 9624, ISO 7005-1.
- Australian Standards: AS/NZS 4331.1, AS 4087, AS 2129 Table D, Table E.
- Norwegian Standards: NS 2545, NS 2546, NS 2547, NS 2525, NS 2526, NS 2527, NS 2529, NS 2537, NS 2538, NS 25239, NS 2542, NORSOK L-005.
- Other Standards: GOST 12820-80, GOST 12821-80, MSZ flange, NFE 29203, VSM 18695, VSM 18696, VSM 18697, VSM 18716, VSM 18718, VSM 18703, JIS B2220, KS B1503, KS D4308, KS D3578, KS B2332, KS B2333, KS B6216, SABS/ SANS 1123.