https://www.nickelalloytubes.com/products/steel-pipe-tube-fitting/ STEEL FITTING Steel has been used for making pipe and pipe fittings for years for its durability and strength. Moreover, steel also offers high resistance to heat. This property also adds to the popularity of steel for making pipes and pipe fittings. As steel hose fittings tend to rust, they are often mixed with other materials to add to their durability and make them rust-resistant.