Pressure Relief Valves

Pressure Relief Valves

A pressure relief valve is used to release excess pressure from a system during overpressure situations thus avoiding catastrophic failure. So, a Pressure relief valve is an important process safety device and is widely used in the chemical, petrochemical, power, and oil and gas industries. The pressure relief valve (PRV) is designed to open at a predefined set pressure. So whenever the system pressure exceeds the set pressure, the PRV pops and releases the overpressure and when the excess pressure is removed the PRV closes again. A pressure relief valve (PRV) or relief valve is a type of safety valve used to control or limit the pressure in a system; pressure might otherwise build up and create a process upset, instrument or equipment failure, or fire.

The pressure is relieved by allowing the pressurized fluid to flow from an auxiliary passage out of the system. The pressure relief valve is designed or set to open at a predetermined set pressure to protect pressure vessels and other equipment from being subjected to pressures that exceed their design limits.

When the set pressure is exceeded, the pressure relief valve becomes the “path of least resistance” as the valve is forced open and a portion of the fluid is diverted through the auxiliary route. In systems containing flammable fluids, the diverted fluid is usually routed through a piping system known as a flare header or relief header to a central, elevated gas flare where it is usually burned and the resulting combustion gases are released to the atmosphere.