Spirax Marshall Safety Valve: Reliable Industrial Overpressure Protection

Manufactured by Forbes Marshall, the Spirax Marshall Safety Valve is an automatic overpressure protection device designed for steam boilers, air receivers, and process pipelines. It automatically lifts at a pre-set pressure threshold to discharge excess volume, preventing pressure spikes from causing equipment failure.

Available in sizes ranging from 15 NB to 200 NB, these valves are built across various body materials—including cast iron (such as the SV11 model), carbon steel, and stainless steel—to suit diverse thermal and chemical applications.

Core Performance & Features

• Automatic Overpressure Discharge: Opens rapidly at set pressure to vent media, maintaining system operating parameters within safe thresholds.
• Broad Material Selection: Cast iron (SV11), carbon steel, and stainless steel options handle non-corrosive steam, compressed air, or aggressive fluids.
• Wide Pressure Spectrum: Adjustable set pressure ranges support low-pressure boilers up to high-pressure industrial lines exceeding 200 bar.
• Cost-Effective Utility Security: Entry-level standard configurations typically start around ₹3,900.
• Multiple Connection Styles: Available in screwed (BSP/NPT) or flanged end connections to match standard piping layouts.

Technical Specifications

Selection & Sizing Best Practices

• MAWP Alignment: Set pressure must be configured to match or remain below the Maximum Allowable Working Pressure (MAWP) of the protected vessel.
• Capacity Sizing: Calculate discharge capacity strictly in accordance with ASME or API sizing standards to ensure the valve can handle total boiler output during emergency conditions.
• Media Matching: Match internal trim and body metallurgy directly to process media to avoid premature seat pitting and leakage.
• Routine Inspection: Conduct periodic pop-tests and seat inspections to clear scale build-up and verify free movement of the spring assembly.