Safety Relief Valves for Natural Gas Systems
USG safety relief valves are engineered to protect gas systems from dangerous over-pressurization in transmission, distribution, metering, and industrial applications. When regulators, bypass valves, or other pressure-control devices fail or leak, relief valves provide a critical last line of defense by automatically venting excess pressure to the atmosphere and maintaining system integrity.
Designed for large-capacity relief applications, USG mechanical relief valves offer dependable performance, rugged construction, and economical installation. They are widely used in natural gas systems where pressure buildup during low-load or off-peak conditions can otherwise lead to unsafe operating conditions.
Specifications
Available Models
- Model 257-S: Spring-operated safety relief valve featuring a roll-out diaphragm and double-ported soft-seat valve for large-capacity relief with minimal pressure buildup.
- Model 250-S: Spring-loaded safety relief valve with angled body and deep molded diaphragm for high flow capacity.
- Model 250-DW: Dead-weight loaded safety relief valve offering precise relief pressure control for low-pressure applications.
Construction
Body Materials: Cast iron (ASTM A126 Class B)
Diaphragm: Buna-N with fabric reinforcement (model dependent)
Valve Trim: Soft-seat designs for tight sealing and reliable reseating
Housing & Internal Components: Heavy-duty construction for durability, corrosion resistance, and long-term reliability
Pressure & Size Ranges
- Pipe Sizes: 2", 3", and 4" (NPT and ANSI flanged configurations available)
- Relief Pressure Ranges: Approximately 2 oz to 100 psi, depending on model and spring selection
- Maximum Working Pressure: Up to 175 psi (model dependent)
For detailed sizing guidance, capacity tables, spring selections, and dimensional data, refer to the product documents above.
Safety Relief Valve Features
Large-Capacity Pressure Relief
Designed to safely discharge excess gas volume and maintain pressure below predetermined limits.
Mechanical Spring-Loaded or Dead-Weight Loaded Design
Opens automatically when system pressure exceeds the set point and reseats tightly when pressure returns to normal.
Roll-Out Diaphragm Technology (Model 257-S)
Minimizes pressure buildup above set point while delivering maximum relief capacity and accurate repeatability.
Angled, High-Flow Body Design (Models 250-S & 250-DW)
Large exit areas support high flow rates and allow valve removal without disturbing piping.
Weatherproof & Watertight Construction
Suitable for indoor or outdoor installations in utility and industrial environments.
Ball-Check Diaphragm Sentry (Select Models)
Maintains relief protection in the event of diaphragm failure.
Benefits
- Improved System Safety: Protects downstream piping, meters, and equipment from over-pressurization events.
- Reliable Final Pressure Protection: Provides a dependable safeguard when regulators or bypass valves fail.
- High Discharge Capacity: Supports large gas volumes in distribution and industrial applications.
- Simple Installation & Operation: No external power or controls required. It operates automatically based on system pressure.
- Long Service Life: Heavy-duty materials and proven designs ensure dependable performance over decades of service.
Capability
USG safety relief valves are designed for a wide range of gas system protection requirements.
- Application Types: Gas distribution systems, district regulator stations, metering sets, city gate stations, industrial gas systems
- Gas Compatibility: Natural gas, propane (LP gas), nitrogen, dry COâ‚‚, air, and other non-corrosive gases
- Installation:
- Indoor or outdoor installations
- Typically installed vertically with discharge piping to a safe vent location (not recommended for buried service)
- Relief Pressure Ranges: From ounces of pressure through high-psi relief applications (model dependent)
Talk to an Industrial Gas Control Expert
Whether you’re specifying industrial gas regulators, selecting industrial relief valves, or upgrading critical gas infrastructure, we can help you identify the right solution for your application.
