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What are Safety Relief Valves & Purpose of Safety Relief Valves?

What are Safety Relief Valves

Safety Relief Valve


A Safety Relief Valve is a pressure Relief Valve marked by rapid opening or pop action or by opening in proportion to the increase in pressure over the opening pressure depending on the application. These relief valves offer significant advantages in the manufacturing, energy production, and transportation sector. Investing in Industrial valve repair and maintenance ensures the safety of workers and the property.


Going by documented records, the First Safety Relief Valve was invented in 1681 by Denis Papin, a French inventor to prevent the overpressure of his steam-powered digester. However, with fast growth in science and technology, the Relief Valves have been upgraded to meet the demands of the dynamic market. Contemporary industrial relief values are classified as conventional spring-loaded, balanced spring-loaded, and pilot-operated.


Purpose of Safety Relief Valves


The main function of a Safety valve is the security of life, property, and surroundings. It safeguards life and property by guarding against failure to control system pressures. Safety Relief Valve is the last call of action of reducing system pressure by releasing flow before total failure.


 Safety Valves are fully automated and used in boilers, pressure valves, and pipelines. Generally, the control pressure does not exceed the specified value. However, there are several reasons why the pressure in a vessel or system can exceed a predetermined limit. Common causes of overpressure are


  • Blocked discharge
  • Exposure to Fire
  • Thermal Expansion
  • Chemical Reaction
  • Heat exchanger tube rupture
  • Cooling system failure


If the pressure inside an unprotected pressure valve or system rises above the safe pressure level, then both the plant and workers could suffer devastating consequences. A safety relief valve’s primary objective is to safeguard any pressurized system from the consequences of exceeding its intended pressure limit. 


These valves automatically release liquid or gas pressure from the consequences of exceeding its Intended pressure limit. These valves automatically release liquid or gas pressure from any pressure-containing system, preventing excessive pressure and safeguarding equipment and people. A safety valve needs to be correctly sized, chosen, fitted and maintained to fulfill all these requirements.


Components of Conventional safety relief valve


  • Cap –The safety valve cap, which may be threaded or fastened to the bonnet with a bolt, is the top portion that conceals the adjustment screw.


  • The bonnet is the valve’s central section and contains a stem, spring, buttons, and guide plate. This device could be open or closed.


  • Body-The body is the bottom-most part and contains a disc, disc holder, locking nut, and nozzle blow-down ring.


  • Adjustment Screw The calibration of a pressure safety valve at a given fixed pressure is attained by adjustment 


  • Stem-This component distributes the spring force to the disc assembly while also aligning the parts.


  • Spring and spring buttons-.A spring will keep the valve closed and the spring button can evenly distribute pressure.


  • Lift lever-Manual pressure release is achieved via the lift lever


  • Disc and Disc Holder-This device would be impacted by process pressure and susceptible to  galling, erosion, and pitting


  • Nozzle-The process fluid enters the valve through a channel called a nozzle. They come in a variety of styles, including fully threaded, and removable, partially threaded and removable, partially welded in the valve body, and partially pressed and removable.


How to select the right safety relief valve?


We will consider five criteria for selecting a safety relief valve


Connection Size


The valve size must be proportional to the size of the inlet or discharge piping. The National Board has specified both inlet piping and discharge piping should be as large as the opening of the valve.


Set Pressure


The set pressure must not exceed the maximum allowable working pressure. (MAWP).of the boiler or vessel. The valve must open below or above the MAWP of the equipment. Under normal conditions, MAWP should be 10% greater than the expected highest operating pressure.




The temperature has a direct impact on the volume and viscosity of the gas or liquid flowing through it. Temperature is the determining factor for selecting material for valve construction. For instance, Steel valves are used for high operating temperatures over bronze or iron.


Back Pressure


Back pressure is pressure on the outlet side of the pressure relief system as a result of pressure in the discharge system. It can affect the set pressure of the upstream valve and make it pop open repeatedly damaging the valve.

During the installation of varied back pressure, valves should be selected so that back pressure does not exceed 10% of the valve set pressure.


Required Capacity


Safety relief valves must be able to relieve pressure at a certain capacity. The required capacity is determined by the size of the valve, the temperature of the media, and the relief discharge area.


The safety relief valve is for safeguarding the lives of workers, property, and the environment against unwarranted crises. Install this system in your plant as a  safety measure.  For placing an order contact authorized dealers for minimum cost and maximum productivity with a warranty.


Fidicon Devices is a reputed Safety Relief Valve Manufacturer in India, you can buy Safety Relief Valve at the best price.