1. Safety Valve Fundamentals

1.1 Definition and Function

A safety valve (pressure relief valve) is an automatic safety device designed to protect pressurized systems from overpressure conditions. When system pressure exceeds a predetermined set point, the valve automatically opens to discharge fluid, preventing potential equipment failure or hazardous situations.The main safety valve product names of China Safety Valve Network include:Freezer-used Safety Valve,Gas Specific Fall Lift Safety Valve,GA49H-DN20 Pulse Safety Valve,High Temperature and Pressure Fall Lift Safety Valve,Hydraulic Safety Valve,Impulse Safety Valve,Impulse Spring Safety Valve,JIS Safety Valve,Main Safety Valve,Overflow ValveOil Refining Specific Safety Valve,Pulse Safety Valve,Pilot Safety Valve,Pressure Safety Valve

1.2 Operating Principle

The valve's disc remains closed under normal operating conditions, held in place by a spring or other loading mechanism. When system pressure overcomes the spring force, the disc lifts, allowing controlled fluid discharge. Upon pressure normalization, the spring force reseats the disc, restoring system integrity.

2. Safety Valve Classification and Selection

2.1 Classification by Lift Height

d₀ = Minimum nozzle bore diameter

2.2 Classification by Design

• Spring-loaded: Most common, compact design

• Lever and Weight: Simple adjustment, limited application

• Pilot-operated: High accuracy, suitable for high pressure/vacuum

• Bellows: Balanced design for variable backpressure

2.3 Body Configuration

• Closed Bonnet: Discharge directed to piping system (hazardous/corrosive media)

• Open Bonnet: Discharge to atmosphere (air, steam, non-hazardous gases)

2.4 Selection Criteria

• Set Pressure: Must exceed normal working pressure by 10% minimum

• Capacity: Based on maximum possible system inflow

• Medium: Compatibility with valve materials

• Temperature: Affects material selection and spring performance

• Backpressure: Considered in balanced valve selection

Critical Note for Spring Valves: Within one nominal pressure (PN) range, multiple spring ranges exist. Always specify exact set pressure when ordering to avoid receiving maximum pressure configuration.

3. Safety Valve Installation Requirements

3.1 Installation Position

• Vertical installation mandatory for proper disc guiding

• Mount directly on equipment nozzle or short, straight inlet piping

• Ensure unobstructed access for maintenance

3.2 Piping Considerations

• Inlet piping: Minimum pressure drop (max 3% of set pressure)

• Outlet piping: Adequate diameter, low backpressure

• Drain holes: Provided in discharge piping for condensate removal

• Support: Proper piping support to avoid valve stress

3.3 Pre-installation Verification

• Pressure testing of connected system

• Set pressure verification at test bench

• Seat tightness inspection

• Cleaning of protective covers and internals

4. Maintenance and Inspection Protocol

4.1 Regular Inspection Schedule

• Visual inspection: Monthly for signs of leakage, corrosion

• Operational test: Quarterly manual lifting test

• Bench testing: Annual full performance verification

• Internal inspection: Every 3-5 years or as required

4.2 Maintenance Procedures

1. Isolation: Secure system and depressurize completely

2. Disassembly: Carefully remove valve following manufacturer guidelines

3. Cleaning: Remove deposits from disc, seat, and guiding surfaces

4. Inspection: Check for wear, corrosion, or damage

5. Replacement: Install new components as needed

6. Reassembly: Follow torque specifications for bolting

7. Testing: Verify set pressure and seat tightness

4.3 Common Issues and Solutions

5. Industry Standards and Compliance

• ASME BPVC Section I & VIII: Design and certification requirements

• API 520/521: Sizing and selection guidelines

• ISO 4126: International safety valve standards

• National/Regional Regulations: Local pressure equipment directives

6. Best Practices Summary

1. Proper Sizing: Calculate required capacity accurately

2. Correct Selection: Match valve characteristics to service conditions

3. Professional Installation: Follow manufacturer and code requirements

4. Documentation: Maintain complete valve history and test records

5. Training: Ensure personnel competence in operation and maintenance

6. Spare Parts: Maintain critical spare components for critical services                         Do you still need to know or purchase the following safety valve products:

7. • JIS Safety Valve
   • Main Safety Valve
   • Overflow Valve
   • Oil Refining Specific Safety Valve
   • Pulse Safety Valve