Overpressure Protection: Relief Valve Working Principles
Essential Safety Systems for Gas Pipeline Pressure Control
⚠️ Critical Safety Note
Overpressure protection is a fundamental consideration in all pipeline system designs. Its purpose is to maintain the downstream pressure of the regulator at a safe maximum value. Without proper protection, system failure can result in catastrophic consequences.
Understanding Overpressure Protection
A high-pressure transmission and distribution system delivers natural gas through a regulator to a low-pressure system serving individual users. The regulator, piping, and gas handling equipment are protected against overpressure conditions by relief valves.
The relief valve setpoint is adjusted to a pressure level determined by the minimum maximum rated pressure value of the low-pressure system components.
How Overpressure Occurs
Overpressure occurs when system pressure exceeds the setpoint of the equipment controlling it. This indicates an error in the system (typically at the upstream regulator). If this pressure is not limited, it can lead to complete system failure.
To implement overpressure protection:
- Identify the weakest part of the system
- Limit excessive pressure below the maximum rated pressure of that component
Maximum Pressure Considerations
Check the following components to determine the weakest part of the pressure-containing system:
🔧 Downstream Equipment
The downstream component with the smallest maximum rated pressure (appliances, burners, boilers, etc.) determines the highest pressure value for all downstream equipment.
⚙️ Main Regulator
Regulators have different pressure ratings: inlet pressure, outlet pressure, and internal pressure. The minimum of these determines the maximum allowable pressure.
🔄 Piping
Piping is limited by its pressure-containing capacity. Besides physical limitations, practical applications must comply with one or more applicable rated pressure codes or regulations.
Key Principle: 그만큼 lowest value among these three maximum rated pressures becomes the maximum allowable pressure for the entire system.
Relief Valve Function
Relief is accomplished through a device that vents fluid to another low-pressure system (usually the atmosphere) to maintain the downstream pressure of the regulator at a safe maximum value.
⚠️ Important Safety Requirement
Relief valve discharge must be directed to a safe location. Proper venting is essential for safe operation.
Relief valves are considered the most reliable overpressure protection method available and come in many different forms.
Fisher Relief Valve Series
Note: Fisher relief valves are NOT ASME safety valves. They are designed specifically for gas pressure regulation applications.
YUNRUI provides complete Fisher relief valve solutions for natural gas systems.
Common Fisher Relief Valve Series
| 시리즈 | 유형 | 응용 프로그램 |
|---|---|---|
| Fisher H200 Series | 릴리프 밸브 | Low-pressure gas systems |
| Fisher H800 Series | 릴리프 밸브 | Medium-pressure applications |
| Fisher 289 Series | 릴리프 밸브 | Commercial/industrial systems |
| Fisher 627 Series | Relief Valve/Backpressure | Direct-operated regulators |
| Fisher 630 Series | 릴리프 밸브 | High-capacity relief |
| 피셔 MR98 시리즈 | 릴리프 밸브 | Compact design applications |
| Fisher EZR Series | 릴리프 밸브 | High-pressure transmission |
| Fisher 63EG Series | 릴리프 밸브 | Pilot-operated systems |
Selection Guidelines
압력 등급
Select valve based on system maximum allowable pressure and required relief capacity.
유량 용량
Ensure adequate flow capacity for worst-case overpressure scenarios.
Vent Location
Plan safe discharge routing away from ignition sources and occupied areas.
결론
Proper overpressure protection is essential for safe gas system operation. Relief valves provide the most reliable protection by venting excess pressure to a safe location before system components are damaged.
When selecting relief valves, always consider the weakest component in your system and ensure the relief valve setpoint is below its maximum rated pressure. Fisher relief valves offer proven performance across a wide range of pressure ratings and applications.
핵심 요약
- Overpressure protection is fundamental to pipeline safety
- Identify the weakest system component first
- Set relief valve below minimum rated pressure
- Ensure safe venting to atmosphere
- Fisher relief valves are NOT ASME safety valves
