Water is distributed in steel pipes, either 20 or 40 ft (6 or 12 m) long. Each piece is coupled to the next, either by direct welding or via pipe fittings or flanges (called couplers.) There are several ways to couple water pipes together:
•    They can be abutted directly together, using a single circumferential weld
•    They can be sleeved with flanges that extend over the ends of the two pipes, creating two circumferential welds. This is known as the girth welded joint.
•    They can be connected via pipe fittings (called bell housings) which are factory formed in the wall of one pipe, and then welded to the adjacent pipe. This is the most common coupling used in water systems, combining the benefits of single welds that incorporate flanges

Affordable pipe fittings are a necessary part of delivering household drinking water, and a lot of research has gone into improving their design, particularly in areas prone to earthquakes. A common cause of fatalities in these regions is lack of a clean water supply. Often, the cause is not fractured pipes, but failure at the pipe flanges.

A bell housing is made by inserting a mandrel into one end of the pipe, and expanding it until room is created to insert the adjoining end. This means each pipe section has a bell housing at one end, and a prismatic spigot joint at the other. Understanding the how compression, tension, pressure loading and cyclic stresses affects these joints is an important concern in urban areas prone to earthquakes. Research is concentrated on new pipe fittings with improved stress resistance.

We at Chemipetro supply pipe flanges for an entire range of industries, using alloys that are both strong and corrosion-resistant, such as super duplex.