The metals used for pipe & fittings usually include: Stainless Steel (SS), SS 304, SS 316, Galvanised Steel, Malleable Steel, Black and Malleable steel etc. Each material is suited for a particular application, which in turn depends up on the physical and chemical properties of the material.

Steel also known as Black steel is rigid material and has a low coefficient of thermal expansion, which minimizes the need for expansion fittings. Black steel pipes are usually used for heating systems in which the hot water or steam is continuously circulating as they are comparatively cheaper and more stronger compared to other materials but requires additional support due to its weight. If there is chance of condensation formation in the piping network, it is recommended to use Schedule 80 Black Steel pipes for increasing the time needed for failure by corrosion.

Galvanization is the process of coating steel pipes with a layer of zinc to enhance the resistance corrosion at ambient conditions. Even though they are more expensive comparatively, they can be used at any corrosive environments for applications requiring frequent humidification and drying up. It cannot be used for water treatment operations involving high concentration of sodium, which results in the failure of the galvanisation film layer and requires careful examination while it is being welded. Since it is difficult to coat the inner surface with galvanising layer, it is recommended to attach mechanical couplings with the piping network.

There are many grades of Stainless Steel viz. 300 series alloys used for corrosion-resistant and nonmagnetic application, 400 series alloys are used for high temperature applications, 200 series alloys having the least corrosion resistance are used in sinks. The most commonly used is SS 304 alloy [18% Cr & 8% Ni] has better resistance to corrosion and can be easily welded without any traces of corrosion. While SS 316 [Adding Mo to SS 304] has a better resistance to chemical etching by chlorides. Alloys of SS can be used for various applications which can supply some amount of oxygen for protective oxide layer formation at the surface [similar to Al alloys] like domestic heating and cooling water systems.

CI mainly used for conveying sewer and storm water owing to its high resistance to corrosion. Mostly cast iron joints are either push fittings or threaded, push fittings can be used for underground piping system where the soil surrounding it helps in giving a restrained support while CI pipes cannot be use above ground due to the high possibility of separation in case blockage.

DI is similar to CI except for its lower concentration of carbon and additives such as Mg, which makes it easier to perform the annealing surface treatment DI is more stronger and less resistant to corrosion compared to CI. DI is used conveying city, storm & sanitary sewer water.

Malleable cast iron is a annealed form of white CI with similar composition to that of CI with slightly more amounts of carbon and Si. Malleable CI is formed as a result of more time consuming surface treatment process in comparison to DI, resulting in higher strength in tension, more ductility & toughness, higher resistance to corrosion, better damping capacity & fatigue strength. There are two types of malleable CI, namely black and white malleable CI. They are mainly used for applications like bearing caps, electrical and pipe fittings etc.