Malleable iron pipe fittings hold two different pipe parts together and direct the gas and liquid movement. Some malleable pipe fittings are threaded, meaning that they have grooved ends that allow plumbers to screw the pipe fittings on the pipes, letting plumbers connect different pipes together.
Malleable iron pipe fittings can come in black and galvanised finishes. The three forms of malleable cast iron include whiteheart, blackheart and pearlitic malleable cast iron. The surface zone of the whiteheart malleable cast iron has ferrite. The intermediate zone has temper carbon, ferrite and perlite. Tempering refers to the hardening of metal. Blackheart malleable cast iron is mostly made of ferrite. The pearlitic malleable cast iron is made from perlite and other austenite products. Perlite is made from alternating layers of ferrite and cementite.
Malleable pipe fittings come in a variety of shapes, depending on the applications that the plumber will use the fittings for. These shapes can include the elbow, a fitting that curves to send the pipe in certain direction. Another pipe fitting type, the side outlet elbow, is like the regular elbow, but has an added side outlet. The tee has three openings, with two on both ends of the pipe and one on one the side. The side outlet tees have four openings, one that is the side outlet. The cross has four openings, with each opening having a corresponding opening on the other side. These different fittings allow the plumber to send pipes in different directions and let pipes feed into each other.
Malleable cast iron is an alloy of iron carbon that engineers treat with heat. When first cast, the iron does not have any graphite. All the carbon content is in cementite form. Malleable iron typically has 2 to 3 per cent carbon, 1 to 2 per cent silicone, 0 to 1 per cent manganese and small amounts of sulphur and phosphorus. Malleable iron has a high toughness due to its nodular graphite and the low-carbon content. Graphite forms in a way that makes the graphite not spherical but irregularly shaped.
Engineers prefer malleable iron for parts that need to be coined, pierced or cold-formed. Cold forming refers to the process of rolling or pressing thin gauges of steel sheet into usable materials. Malleable iron works well for parts that need to have the most machinability, meaning the parts are easy to make using a machine. It also works well with pieces that need to resist impact under cold temperatures.