Oilfield equipment provider Rotork has received an order to supply 220 pneumatic actuators for the Phase II of the Nasr full field development project in Abu Dhabi.
The aim of the project operated by Emirati oil giant ADNOC is to increase the field’s oil production capacity to 65,000 barrels per day (bpd) from the existing capacity of 22,000 bpd.
Awarded by Hyundai Heavy Industries, the order included spring-return pneumatic actuators to operate 30″ and 36″ Class 1500 ball valves, with the specification that the maximum actuator output torque at a design pressure of 9.4 bar should not be in excess of 90% of the valves’ maximum allowable stem torque (MAST).
Due to the huge force required to compress the spring, this requirement is beyond the performance limits of the standard range of Rotork GP pneumatic actuators.
However, faced with this challenge, the Rotork’s Research & Development department successfully created an innovative and simple solution.
Rotork engineers added a second pneumatic cylinder, mounted between the GP scotch yoke centre body and the spring-return cylinder. Both cylinders are pressurised in the same direction at the same time, so one delivers torque for valve movement, satisfying the valve MAST requirement, whilst the other independently applies the torque to compress the spring.
The resulting actuator is the largest GP350 actuator built to-date, with a total length of 8.5 metres and weighing 19 tonnes.
