Industrial Safety Valves: Types and Correct Selection

In sectors such as petrochemicals, power generation, chemicals and food processing, the safety of pressurised systems is a top priority. Unexpected pressure rises can cause equipment damage, production losses and serious accidents. Industrial safety valves are the last line of defence: they open automatically when pressure exceeds the permitted limit and protect the system. In this field, ORFA supplies ARI-Armaturen safety valves.

This article explains how safety valves work, the main types, the ARI-Armaturen product series and the criteria to consider for correct selection.

What Is a Safety Valve and How Does It Work?

A safety valve opens by itself, without any external energy, when system pressure reaches the preset opening pressure (set pressure), and discharges the excess pressure. In normal operation the disc is held against the seat by spring force and the valve stays closed. When the pressure force exceeds the spring force, the disc lifts and the medium is discharged. Once the pressure falls back to a safe level, the valve closes again.

Safety valves protect pressure equipment such as steam boilers, pressure vessels, heat exchangers, compressors and pipelines.

Full Lift and Proportional Lift Safety Valves

ARI-Armaturen Safety Valve Series Supplied by ORFA

• ARI-REYCO R Series (API 526, full nozzle): ANSI/ASME flanged; for high-pressure applications and high relieving capacity, with material options for steam, gas and liquids.
• ARI-SAFE Series (Fig. 901/902/911/912), flanged: DIN/EN flanged, full-lift and standard-lift versions; grey cast iron, ductile iron, cast steel and stainless steel bodies. The semi-nozzle SAFE SN and the SAFE 900 versions developed for steam/hot water also belong to this family.
• ARI-SAFE-P Series (Fig. 921–924), flanged: For small relieving capacities, DN15–DN150; various body materials.
• ARI-SAFE-TC Series (Fig. 941–946), threaded: Full-lift and standard-lift versions for small-bore applications; DN15–DN25, PN40; ductile iron or stainless steel body.
• ARI-SAFE-TCS (Fig. 951–953) and ARI-SAFE-TCP (Fig. 961–963) Series, threaded: Stainless steel body, DN15–DN25, PN100; for high-pressure applications with set pressures up to 100 bar.

Selecting the Right Safety Valve

Safety valve selection and sizing directly affect system safety. The following data should be defined before ordering:

• Medium: Steam, gas, air or liquid.
• Set pressure: Chosen so as not to exceed the maximum allowable pressure of the protected equipment.
• Operating temperature: The system’s maximum operating temperature.
• Required relieving capacity: Enough to discharge the excess flow safely in the worst credible case.
• Connection type and size: Flanged or threaded, and inlet and outlet nominal sizes.
• Back pressure: The effect of pressure in the discharge line on valve selection.
• Material compatibility: Body and trim materials suited to the corrosive properties of the medium.

Frequently Asked Questions

Conclusion

Industrial safety valves are indispensable for the safety of pressurised systems and the people who work around them. Choosing a valve that matches the medium, set pressure and required capacity determines how effective the protection is. Explore ARI-Armaturen safety valve options in our safety valves product group, or contact the ORFA technical team for selection support.