Abstract: Restriction orifices are widely adopted in safety relief systems.? Relevant analyses or calculations have been performed for safety restriction orifices under conditions of control valve failure, thermal expansion, and emergency overpressure relief. Through calculation and analysis, safety restriction orifices can play an important role in reducing safety valve discharge, lowering pressure drop in control valves, and reducing the risk of pressure relief, thereby achieving energy conservation and emission reduction, cost savings and investment reduction.

Key words: restriction orifice, control valve; safety valve, safety instrumented system