The National Gas Company of Trinidad and Tobago Limited is using the largest Dantorque™ actuator ever produced by Emerson to help expand its gas distribution network on the Caribbean nation of Trinidad and Tobago. The actuator, which is 2.4 meters tall and 1.64 meters in diameter, will be used to isolate the gas being supplied from Trinidad’s northern offshore gas fields in the event of an emergency situation.
The multi-million dollar project covers a range of valve automation products from Emerson, including a Dantorque subsea gear operator and one smaller spring return actuator, three Shafer™ subsea actuators and 11 Shafer gas-over-oil actuators installed on the offshore-platform and land portions of the pipeline.
The development of new gas fields off the northeast shores of Trinidad required new pipelines to be connected to the existing pipeline infrastructure, which is all in the south. The tie-in to the large 91 cm diameter existing pipeline required a spring return actuator with ROV (Remote Operated Vehicle) override capability. To meet this requirement, Emerson supplied a DTUS 171/1350 Dantorque actuator which has a spring ending torque of 102,500 Nm (907,800 in-lbs) and weighs nine metric tons (9.92 short tons).
The National Gas Company of Trinidad and Tobago Limited (NGC) has been a long-time user of Shafer rotary vane actuators and gas-over-oil actuators. The Dantorque actuator met all of the requirements for optimum envelope dimensions and diver-assisted installation and retrieval capability.
The Dantorque DTUS actuator converts the linear motion of a spring into rotation through helical spline gearing technology. The mechanical spring return package is based on the Belleville (disc) spring principle, which is well proven. Through this unique combination of the helical gearing mechanism and the Belelville disc spring principle, the Dantorque DTUS provides an extremely compact package for the amount of torque being produced.
[mappress] Subsea World News Staff , January 30, 2012; Image: Emerson