Tee fittings are mainly used where tube connections are required to place at both side 90 degree angle in the piping systems.Tee fittings are also available with weld nipple type where it can resist Very High working pressure in piping systems upto 600 bar (9000 Psi)
Stainless steel fittings are widely used in piping systems where there is high corrosion area , high watery areas , high chemical & highly explosive areas where temp resistance & reaction with chemicals & risk of corrosion is very high & which is to avoid so Stainless steel fittings are used.