Production • Processing • Handling
Digital valve monitoring and partial stroke testing
Richard Hudd reports on how smart valve monitoring delivers a networked solution for increased partial stroke test functionality.
installation in the Middle East. Te system is designed to deliver predictive maintenance information from widely distributed areas for use by the operators to reduce shutdowns and improve overall plant efficiency. Tis is made possible by the ability of the SVM to be integrated into an existing Ethernet and fibre optic infrastructure, enabling over one hundred monitored valve actuators on wellheads at numerous locations to be networked over distances of 10km or more.
T
Te SVM field control units on this project are attached to the ESD circuits for shut off valves installed in sets of two and four on more than fifty wellheads. Analysis is performed on the SVM server computer in the centralised control room. Communication between the wellhead sites and the computer is fully integrated within the operator’s existing network infrastructure. Te SVM field units are incorporated into the
Ethernet network that links other equipment and instrumentation at each wellhead site. A fibre optic link is then used to transmit the data to intermediate engineering and control stations at two manifold sites. From these sites, fibre optic links are again used to transmit data from all the wellheads to the centralised control room. Partial stroke testing (PST) is a function used in a safety instrumented system (SIS) to enable the operator to identify possible failure modes on a shutdown or emergency shutdown (ESD) valve without the need to completely close the valve and hence disrupt the process. Partial stroke testing is an accepted hydrocarbon industry standard technique that is quantified in detail by regulatory bodies such as the IEC and ISA. Te partial valve stroke prevents unexpected
failure on demand of the safety function and demonstrates that certain potential problems that would otherwise go undetected, such as spring fractures in the spring chamber of the pneumatic
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he Rotork Smart Valve Monitoring (SVM) system has been selected to provide a networked solution for digital valve monitoring and partial stroke testing on a large scale oilfield
actuator, are not present. Consequently, the interval for testing for these otherwise undetected errors can be extended.
Te Rotork Smart Valve Monitor incorporates several features that are not available from other systems, as well as providing detailed diagnostic data that allows the operator to plan for strategic preventative maintenance. Te key to the SVM’s reliable performance is its separation from the valve’s control system. Tis enables the operator to design the control system exactly to suit the routine and safety requirements without having to compromise for the testing programme. Te SVM system is powered by the control signal to the actuator’s solenoid valve. Te monitoring function is then provided by a pressure transmitter located between the solenoid valve and actuator which records the instrument pressure changes
Fig. 1. The Rotork SVM field unit is incorporated on the valve actuator control panel for hazardous area applications.
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