Valve actuators - vital elements for fireproofing and overall plant safety
In any oil and gas installation the requirement for safety is paramount and recent accidents at refinery and tank farm sites offer vivid illustrations of the catastrophic consequences of such events.
Valve actuators have an important impact on safety as vital components for the movement and isolation of bulk liquids, providing not only the muscle to open and close the valves but also the brains to communicate their activities and operating condition. The advent of digital communication technology has dramatically enhanced the functionality of modern actuators whilst a long history of development in the oil and gas industry environment has produced a comprehensive range of designs and technologies to meet isolating, modulating, failsafe and ESD (emergency shut down) duties.
Valve actuation company Rotork has extensive experience of tank farm installations. In the early 1960s Rotork began to develop design features in its electric actuators that have become benchmark industry standards. Probably the most significant is O ring double-sealing, born out of the environmental challenges of east Asia, where the practice of fitting breathers and drains to explosionproof equipment caused problems with condensation leading to breakdowns and high maintenance costs with traditionally designed actuators.
Rotork’s solution was to adopt circular spigoted flamepaths as an alternative to the customary flat flanges and fit them with O rings to provide environmental sealing. The result was the first electric actuator designto feature an explosionproof and watertight enclosure. The double-sealing aspect of the design concerned the terminal compartment, where covers could be removed for days on site whilst wiring up was in progress, once again leaving the internal electrics vulnerable to the elements. Double-sealing prevented this through the introduction of a separately O ring sealed terminal bung. As a result, when the terminal cover was removed any ingress of water or condensation could not reach any part of the actuator’s internal electrical parts.
