Fail-Safe Electric Ball Valve

A fail-safe electric ball valve combines a quarter-turn ball valve with an electric actuator that uses stored energy to move the valve toward a predefined fail-safe position when a specified failure condition occurs.

Unlike a standard electric actuator that may remain in its last position after power loss, a fail-safe configuration is designed to perform a defined return action, subject to the actuator mechanism and operating conditions.

Key Selection Factors

• Fail-Safe Position: Select fail-open or fail-closed according to the process safety requirements.
• Failure Trigger: Specify whether the required action is triggered by power loss, control signal loss, or an emergency shutdown command.
• Actuator Torque: Verify that the actuator can operate the valve under the specified differential pressure and process conditions.
• Return Time: Define the required fail-safe travel time and confirm it for the selected valve-actuator assembly.
• Important: Power-loss response, signal-loss response, and emergency shutdown functions are separate requirements. Confirm each function during technical selection.

Available specifications depend on the valve model, actuator configuration, materials, and applicable design requirements.

Applicable Standards
The following standards may be relevant depending on the selected valve design, connections, testing requirements, and installation environment.
Valve Design: API 608, ISO 17292, or ASME B16.34, where applicable.
Dimensions and Connections: ASME B16.10, ASME B16.5, EN 558, or EN 1092-1, as applicable.
Pressure Testing: API 598 or the specified applicable test standard.
Fire-Safe Design: API 607 or ISO 10497, where the valve design is qualified.
Actuator Mounting and Enclosure Protection: ISO 5211 and IEC 60529, respectively, where applicable.
Compliance must be verified against the actual product design and supporting documentation. Listing a standard does not establish that every configuration complies with it.

Fail-Open vs. Fail-Closed

• Fail-Open: Moves the valve toward the open position under the specified failure condition. It may suit applications requiring continued circulation, subject to system safety analysis.
• Fail-Closed: Moves the valve toward the closed position to isolate a line when required by the process safety strategy.
• Application-Specific Selection: The appropriate fail position depends on fluid hazards, equipment protection, process response, and the consequences of loss of flow or isolation.

Failure Triggers & Return Performance

• Power Loss: Confirm whether the actuator can complete the required return movement using its stored energy.
• Signal Loss: Verify whether signal failure initiates a return action or requires separate control logic.
• Emergency Shutdown: Confirm the required command interface, response sequence, and any associated safety-system requirements.
• Return Time & Torque: Validate the specified travel time against valve torque, differential pressure, and actuator operating limits.

Typical Application Areas
Chemical Process Lines: Automated isolation or flow-path control, subject to media compatibility and the process safety assessment.
HVAC & Cooling Systems: Fail-safe positioning in selected circulation, bypass, or isolation circuits.
Water & Wastewater Treatment: Automated valve positioning in treatment, dosing, and filtration systems where compatible with the process.
OEM Equipment & Skid Packages: Integration into packaged systems requiring a defined valve response under specified failure conditions.
Application suitability must be confirmed against operating pressure, temperature, fluid properties, required flow conditions, and the system's safety design.

Product Verification
Pressure Testing: Confirm the applicable shell and seat leakage tests and acceptance criteria.
Material Traceability: Request material certificates and heat or batch traceability where required.
Fail-Safe Function Testing: Verify the specified trigger, return direction, and travel time for the supplied configuration.
Documentation: Request applicable test reports, inspection records, drawings, and certificates for the ordered assembly.
Testing scope and documentation availability should be agreed upon before order confirmation.

Provide the following information to support technical selection and quotation.
Valve & Process Conditions

• Valve Specifications: DN/NPS, pressure rating, body material, seat material, and end connection.
• Operating Conditions: Fluid composition, minimum and maximum temperatures, operating pressure, and maximum differential pressure.
• Valve Requirements: Two-way or three-way configuration, required flow path, and any leakage acceptance criteria.

Actuator & Project Requirements

• Fail-Safe Logic: Fail-open or fail-closed, triggering conditions, and target return time.
• Electrical Requirements: Supply voltage, control mode, input signals, and enclosure protection.
• Safety & Compliance: Applicable hazardous-area requirements, functional-safety requirements, and required certificates.
• Order Details: Quantity, delivery destination, required documentation, and target delivery schedule.

Technical selection should be confirmed before finalizing the valve-actuator combination.

Technical Datasheets: Request model-specific specifications, operating limits, and actuator details.

Dimension Drawings & CAD Models: Request available 2D drawings and 3D files for installation review.

Engineering Selection: Submit operating conditions, valve requirements, fail-safe logic, and electrical specifications for technical evaluation.

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