Balanced bellows safety relief valve is a safety valve incorporating a bellows seal, which prevents discharging fluid entering the bonnet space. They are used for minimizing the effect of backpressure on the performance characteristics, opening pressure, closing pressure, lift and relieving capacity. These valves are used where the relief valves are piped to a class spare system and the back pressure exceeds the set pressure. On valve opening, back pressure acts only on that portion of the disc in the closing direction that overhangs the valve seat. They are used in flow lines, multiphase lines, or for paraffinic or asphaltic crude. An advantage of this type of relief valve is, for corrosive or dirty service, the bellows protects the spring from process fluid. They are commonly used in corrosive and flammable service in the refinery and petrochemical industries.