Flanges are widely used in industrial plants. The pharmaceutical industry, paper pulp mills, petrochemical plants, oil rigs, gas pipelines, water treatment works and food manufacturing plants all use pipe flanges in various forms. Depending on the environment, pipe fittings and flanges may be made from specialised alloys, such as super duplex, to resist physical stresses and corrosion.
A flange connects two pipes together to facilitate flow along a conduit, or attaches to one pipe to end a flow line completely. When fitted, they have the appearance of protruding collars, ribs or edges, and they have the function of both strengthening conduits and joining them to another object while holding them in place. They may attach to pipes, shafts or wheels, and are welded, bolted or attached by some other means.
Pipe flanges vary enormously depending on application. Petrochemical flange manufacturers, such as us at Chemipetro, typically construct our products from specialist alloys such as nickel-chrome molybdenum steel, super duplex and titanium for strength and corrosion resistance, and supply them in a range of specifications including ANSI , API, ISO etc.
Flange faces vary, but include raised-face, ring-joint, flat-face and tongue-and-groove facings. The flange surface lies flush or flat against the pipe, and is then mated to an adjoining flange or complementary surface. The join is then completed by bolting, welding and/or use of a collar for extra strength and protection.
Welded neck flanges are made so the wall thickness matches that of the pipe. They are often used in large-bore pipes, which tend to be of light construction. Threaded flanges do not require welding, and so are suitable for high-pressure systems where post-welding heat treatment is difficult.
Slip-on flanges are made slightly larger than the connecting pipe, creating a tight seal that reacts well to expansion and contraction. Lap-joint pipe flanges are similar, but have curved radii at the bores. Socket-weld flanges are slip-on fittings with a bore and counter-bore.
