Actuators deployed in India

Sarah Kellett reveals how intelligent electro-hydraulic ROSOV actuators were specified for a tank farm expansion project

The latest generation of Rotork Skilmatic SI3 electro-hydraulic actuators have been supplied to one of India's leading state-owned oil companies to operate 42in and 48in triple offset butterfly valves on vital safety-related tank farm duties.

The operator was constructing additional storage tank capacity and had to comply with the safety regulations laid down by the MB Lal Committee, requiring the installation of failsafe actuators for critical tank farm applications.

These valves, known as remote operated shut-off valves (ROSOV), now provide tank overfill protection at the majority of storage facilities owned by the Indian oil industry. The local engineering company appointed as the consultant for design and engineering was initially unclear about the specification of actuators for ROSOV, and was opting to go with a pneumatic failsafe solution.

The Rotork Skilmatic SI range of self-contained electro-hydraulic actuators, combining the simplicity of electrical operation with the precision of hydraulic control and the reliability of mechanical spring-return, has been widely adopted for ROSOV applications around the world. Rotork therefore worked very closely with the consultant and the end user, providing Skilmatic tank farm application details and reference lists, organising technical presentations and live product demos.

This resulted in the decision to adopt the electro-hydraulic solution in the specification for the project. Reliability and safety were key factors for the application together with a requirement for a self-contained, fully integrated actuator with intelligent non-intrusive features and a hand-held setting tool.

Enhanced specification

The latest generation SI3 actuator supplied on this contract has an enhanced specification and increased torque output range of 65Nm to 500,000Nm. The SI3 also offers a wide range of operating speeds, additional ESD options with single or dual inputs, and communication capabilities to suit many diverse applications.

Designed for functional safety applications to SIL2 (1oo1) and SIL3 (1oo2) for use on safety critical applications, the actuators are also offered with enhanced partial stroke testing (PST), enabling valves to be function tested without affecting the process.

Performed either locally with the setting tool or remotely from the control room via hardwire or fieldbus communications, PST tests all the final elements (actuator and valve) by measuring the time to move to a set position whilst monitoring the pressure. PST results are recorded by the integral datalogger, shown on the display screen and optionally remotely indicated.

All actuators are available with hazardous area certification encompassing ATEX, INMETRO, IEC, FM, CSA and GOST. The double-sealed electric enclosure is watertight and dustproof in ratings up to IP68 (submersed to a depth of 7m for 72 hours).

Specifiable for single-phase, three-phase or DC electrical power supplies, the Skilmatic SI3 range delivers a range of part-turn torque or linear thrust outputs that are suitable for valves of virtually any size and design.

Sarah Kellett is with Rotork.