SV615 Safety Valve

Installation and maintenance

1. Safety information

Confirm the valve is suitable for the fluid, material, pressure and temperature conditions. Determine the correct installation position and flow direction, and prevent external pipe stresses from acting on the valve.

• Provide safe access, adequate lighting and suitable lifting equipment where required. Equipment above 20 kg should be handled with suitable lifting assistance.
• Identify hazardous fluids, gases, temperatures, pressure and environmental risks before work begins.
• Isolate and safely vent pressure; do not assume zero gauge pressure means the system is depressurised.
• Allow hot equipment to cool and use appropriate protective clothing, tools and genuine replacement parts.
• Work must be performed or supervised by competent personnel under the site's permit-to-work system.
• Protect non-self-draining equipment against freezing where necessary.

Product-specific warning: Do not dismantle the valve before releasing spring compression. The SV615AV and SV615BV soft-seal variants contain Viton/FPM. Material exposed near 315 °C may decompose and form hydrofluoric acid. Avoid contact with dust or fumes and follow current disposal guidance.

2. Spirax Sarco SV615 product information

The SV615 is a full-lift, full-nozzle safety valve for steam, air, inert industrial gases and non-hazardous liquids. It is available in DN15-DN50 with a bronze body and stainless-steel nozzle.

The SV615 complies with EN ISO 4126:2004. Seat tightness complies with ASME/API STD 527 Revision 2002. A Typical Test Report is standard, and EN 10204 3.1 material certification is available on request.

Pressure and temperature reference

Principal material specifications

Principal specifications include BS EN 1982 CC491KM bronze, BS 970 S29 stainless steel, BS 3146 ANC2 stainless steel, ASTM A276 stainless steel, BS 2803 A50 spring steel, BS 2872 and BS 2874 brass, BS EN 12165 CW617N brass, and BS 2056 S42 stainless steel. The Viton soft-seal insert designation is F81.

3. Supply

The valve is normally supplied set to the required pressure and sealed. Setting must only be performed by authorised, competent personnel.

4. Handling

• Transport the valve upright.
• Do not drop it or subject it to sudden shock or heavy impact.
• Keep it in the supplier's packaging until required.
• Never carry a safety valve by its lifting lever.

5. Before fitting the SV615

1. Confirm the proposed installation follows the system arrangement requirements.
2. Blow through the pipework before installing the valve to remove foreign matter that could damage the seat.
3. Confirm the valve has the correct set pressure.

6. Installing the SV615 safety valve

Caution: Prevent liquid jointing compounds and thread sealants from contaminating internal seating faces.

1. Mount the valve vertically upright with its main axis vertical.
2. Use the shortest practical connection to the pipework or vessel.
3. Do not install an intervening valve or fitting that could isolate the safety valve.
4. The inlet connection must not be smaller than the safety valve inlet.
5. Size the discharge system so built-up backpressure does not exceed 10% of gauge set pressure.
6. Route discharge to a safe point and support the discharge pipe independently.
7. Provide a drain at the lowest point where discharge pipework rises.
8. Give each safety valve its own unrestricted discharge pipe.
9. Do not lag the valve. Protect personnel against sudden discharge, heat and noise.
10. Use a wrench on the inlet hexagon; do not grip the body or apply excessive leverage.

7. Damage prevention

Excessive inlet pressure loss can cause rapid opening and closing, reduced capacity, seat damage and leakage. Install the valve 8-10 pipe diameters downstream of bends or converging/diverging fittings. Use a branch radius not less than the inlet diameter, or an inlet area approximately twice the valve inlet area.

8. Commissioning

1. Check inlet and outlet connections for leakage.
2. Raise system pressure and confirm the valve operates at the correct set pressure.
3. Reduce pressure to normal operating pressure and confirm the valve reseats.

9. Testing during use

Include operational testing in a documented and controlled procedure. The test interval depends on application and system conditions and should be agreed by the user or relevant insurer.

Lever test: Do not operate the lever unless system pressure is at least 85% of set pressure. Use hand force only; never use a tool or extension.

10. SV615 setting guidelines

Setting must be performed only by authorised, competent personnel. Adequate differential is required between maximum system operating pressure and set pressure so the valve can reseat. The SV615 achieves rated capacity at 5% overpressure on steam and 10% on air.

Under the BS 5500 setting guidance cited by the source document, the maximum set pressure is the safe working pressure of the protected plant and rated capacity must be achieved with no more than 10% overpressure. The setting-range diagram uses A = 10% of set pressure, with a 0.3 bar minimum, and B = normal system pressure variation.

For metal-seated valves in steam service, Spirax Sarco recommends cold setting on a test rig at 3% above the required set pressure. This does not apply when setting on steam. Unset valves supplied to approved agents must be tagged with the final set pressure. A selection example is SV615AN, DN15, BSPF x BSPF, set at 6 bar g.

11. SV615 safety valve maintenance

All safety valves require planned maintenance. Read the safety information before work. Spirax Sarco recommends periodic return to an authorised local agent for overhaul, testing, resetting and sealing in accordance with industry procedures.