Introduction and Classification of Safety Valves

As a safety valve engineer with 20 years of experience, I'm delighted to share insights into safety valves. These valves are crucial in industrial systems, acting as the last line of defense to prevent equipment overpressure and ensure operational safety.

Safety valves find extensive application across numerous industries. In the petroleum industry, they safeguard oil pipelines, storage tanks, and refining equipment from overpressure during oil extraction, transportation, and processing. For instance, in an oil refinery's distillation column, a safety valve prevents damage if pressure spikes due to unexpected changes in feedstock or process conditions.

In the chemical sector, they protect reactors, chemical storage vessels, and pipelines handling corrosive or reactive chemicals. Take a chemical plant producing fertilizers; safety valves on ammonia synthesis reactors ensure pressure doesn't exceed safe limits, preventing hazardous reactions.

The power industry relies on them for boilers and steam turbines. In a coal-fired power plant, safety valves on the boiler drum release excess pressure if water level or firing rate goes awry, avoiding boiler explosions.

In pharmaceuticals, they're essential for sterilization equipment and pressure vessels used in drug manufacturing. During the production of injectable medications, autoclaves use safety valves to maintain safe pressure during sterilization cycles.

In essence, wherever fluids are stored or processed under pressure, safety valves are vital to prevent equipment failure, accidents, and ensure the smooth running of industrial operations. When the pressure in a system exceeds a preset value, a safety valve opens automatically to discharge fluid, reducing the pressure. Once the pressure drops to a safe level, it closes tightly to maintain system pressure.

Classification of Safety Valves

Safety valves can be classified based on the medium they handle and structural/operating principles, as shown in the diagram:

1. Common Gas Safety Valve

• Natural Gas Safety Valve: Designed for natural gas systems, with materials and structures resisting corrosion from natural gas components. It ensures safe pressure relief in natural gas pipelines and equipment.
• Air Nitrogen Safety Valve: Suitable for air and nitrogen systems, commonly used in industries such as metallurgy and electronics where air or nitrogen is the working medium.

2.Safety Valve for Corrosive Gas

• Hydrogen Sulfide Safety Valve (Bellows & Spring-loaded): Hydrogen sulfide is highly corrosive. The bellows structure prevents medium leakage, and the spring-loaded design ensures accurate pressure control, used in oil and gas industries with hydrogen sulfide-containing media.
• Chlorine Gas Safety Valve (Bellows & Spring-loaded): Chlorine gas is toxic and corrosive. The bellows and spring-loaded combination guarantees tight sealing and reliable pressure relief for chlorine gas systems.

3.Low-density Safety Valve

• Liquid Ammonia Safety Valve (Spring-loaded & Pilot-operated & Bellows): Liquid ammonia has low density and is volatile. The pilot-operated mechanism enables large-capacity relief, and the bellows prevents ammonia leakage, used in refrigeration and chemical industries with liquid ammonia.
• Oil Safety Valve (Spring-loaded & Pilot-operated & Bellows): For oil systems, the spring-loaded and pilot-operated design meets pressure relief needs for different oil viscosities and pressures, with the bellows preventing oil leakage.

4.Saturated Steam Safety Valve

• Low-pressure Saturated Steam Safety Valve (Spring-loaded): Used in low-pressure saturated steam systems (e.g., small boilers), the spring-loaded type is simple and reliable for pressure relief.
• Medium-pressure Saturated Steam Safety Valve (Spring-loaded): Applied in medium-pressure saturated steam scenarios (like industrial boilers), providing accurate pressure control.

5. Superheated Steam Safety Valve

• High-pressure Safety Valve for Power Plant (Spring-loaded): Tailored for high-pressure superheated steam in power plants, with a robust spring-loaded structure to withstand high temperatures and pressures, ensuring the safe operation of power plant boilers and steam turbines.

6. Gas-liquid Mixed Safety Valve

• Gas-liquid Mixed Safety Valve (Pilot-operated & Bellows): For systems with mixed gas and liquid media, the pilot-operated type allows for flexible pressure adjustment, and the bellows prevents medium interaction and leakage, used in complex chemical reactors.

7.Safety Valve for Highly Toxic Media

• Hydrofluoric Acid Type Safety Valve (Bellows): Hydrofluoric acid is extremely toxic and corrosive. The bellows structure ensures no leakage of hydrofluoric acid, protecting the environment and personnel, used in industries handling hydrofluoric acid.

In conclusion, different types of safety valves are developed to meet the specific requirements of various media and operating conditions, playing an irreplaceable role in industrial safety.