Safety Valve Manufacturer in India

A safety valve protects pressure-containing equipment by opening when system pressure reaches the specified set point and discharging excess pressure. Speciality Valve manufactures safety valve configurations for steam, gas, air, liquid and compatible process services. The required configuration is selected based on the credible relief scenario, set pressure, relieving capacity, temperature, fluid properties, back pressure and applicable code requirements.

Safety Valve Pressure and Relief Parameters:

Safety valve performance is determined by the pressure conditions during an overpressure event.

• Set Pressure: Pressure at which the valve is adjusted to begin opening.

• Overpressure: Pressure increase above the set pressure required to achieve the necessary relieving capacity.

• Accumulation: Pressure increase above the equipment's allowable pressure during relief.

• Blowdown: Difference between opening pressure and reseating pressure.

• Back Pressure: Pressure acting at the outlet of the safety valve.

• Relieving Capacity: Required flow that must be discharged during the governing relief case.

These parameters influence the orifice area, spring selection, stability and discharge arrangement of the valve.

Safety Valve Types for Different Relief Duties:

• Conventional Spring-Loaded Safety Valve: Used where back pressure remains within the allowable limits of the valve design.

• Balanced Bellows Safety Valve: Reduces the effect of variable back pressure and helps isolate the spring chamber from the process medium.

• Pilot Operated Safety Valve: Uses a pilot system to control the main valve and may be selected where operating conditions, back pressure or operation closer to set pressure favour a pilot-operated design.

• Steam Safety Valve: Designed for boilers, steam drums, headers and steam-line protection.

• Thermal Relief Valve: Used for pressure generated by thermal expansion of trapped liquid.

Relief Scenarios That Affect Valve Selection:

Safety valve sizing and selection should be based on the governing overpressure scenario rather than pipeline size alone.

Common relief cases include:

• Blocked process outlet

• External fire exposure

• Control-valve failure

• Heat-exchanger tube rupture

• Utility failure

• Compressor or equipment upset

• Thermal expansion of blocked-in liquid

The governing case determines the relieving load that the valve must safely discharge.

How Is Safety Valve Capacity Determined?

Relieving capacity is calculated using the actual process and emergency conditions.
Important sizing data includes:

• Fluid composition and physical properties

• Required relieving flow

• Set pressure

• Relieving pressure

• Relieving temperature

• Allowable overpressure

• Inlet pressure loss

• Built-up and superimposed back pressure

• Discharge destination

Safety Valve Technical Data:

Available sizes, ratings and materials vary according to the selected safety-valve configuration and approved project specification.

Back Pressure, Blowdown and Valve Stability:

Back pressure has a direct effect on safety-valve performance.
A conventional safety valve can be affected by pressure at the discharge side. Where variable back pressure is significant, a balanced bellows or pilot-operated design may be more appropriate depending on the application.

Blowdown also affects valve behaviour. If the valve reseats too close to the set pressure, unstable cycling may occur. Excessive blowdown can keep the valve open longer than required.
Inlet piping should also be reviewed because excessive pressure loss between the protected equipment and the valve can contribute to chattering and unstable operation.

Materials for Steam, Gas and Corrosive Service:

Material selection depends on the process medium, temperature, pressure and corrosion conditions.

Material suitability should be confirmed against the actual fluid composition, concentration, relieving temperature and corrosion conditions.

Where Are Safety Valves Used?

• Pressure Vessels: Protect separators, receivers and other pressure-containing equipment.

• Boilers and Steam Systems: Protect boilers, steam drums, headers and steam distribution lines.

• Gas Compression Systems: Protect compressors, receivers and associated pressure piping.

• Refinery Process Equipment: Provide relief protection for vessels and hydrocarbon-processing equipment.

• Heat Exchangers: Protect equipment where tube rupture or thermal conditions can create excess pressure.

• Blocked-In Liquid Sections: Relieve pressure caused by thermal expansion.

• Storage Vessels: Protect suitable storage vessels against defined overpressure events.

Common Safety Valve Problems and Causes:

Safety Valve Standards and Testing:

Applicable requirements depend on the protected equipment and project specification.

• ASME BPVC Section XIII: Overpressure protection and pressure-relief device requirements.

• API 520: Sizing, selection and installation of pressure-relieving devices.

• API 521: Pressure-relieving and depressuring-system guidance.

• API 526: Dimensions for flanged steel pressure-relief valves.

• API 527: Seat tightness requirements.

• IBR: Applicable where specified for boiler and steam installations.

Inspection and testing may include set-pressure verification, seat leakage testing, lift checks, blowdown verification, shell testing and functional inspection according to the approved specification.

Share the governing relief case, set pressure, required relieving capacity, relieving temperature and back-pressure conditions with Speciality Valve for safety valve selection and quotation.