Rotork Thailand’s Site Services Team assists new pipeline installation

Photographed at the PTT Gas Block Valve Station PN1 on the Bangplee to Saraburi natural gas pipeline, Rotork Thailand’s Site Services Team is supervising a local contractor during the installation of a Rotork GO gas-over-oil actuator on a new emergency shutdown valve.

The Rotork GO actuator (model number GO-100S-140F/D1) is designed to immediately shut the 12 inch, ANSI Class 300 ball valve if a large pressure drop, indicating a leak in the pipeline, is detected.  The actuator uses the pressure of stored gas from the pipeline itself to operate the valve and is equipped with accumulators to allow a minimum of two operating cycles without replenishment.  In this way the actuator can always operate the valve when commanded by the automatic line break system, irrespective of the prevailing pipeline and power supply situation at the time of the emergency.  Operating speed is inherently as fast as conventional hydraulic actuation.

At the centre of the Rotork GO actuator design, a multi-function manifold block integrates the gas and hydraulic functions to meet the specific demands of each application.  These can include altering the speed of valve travel to enable very fast operation during an emergency, with much slower operation to prevent damage to the pipeline during routine operations or partial stroking maintenance programmes.

An additional Rotork safety feature is the TLD torque limiting device, which measures and limits the differential pressure between the gas on the supply side and the oil on the return side of the accumulators to protect both valve and actuator from damage caused by too much torque.  Hydraulic manual override is also provided as standard.

Features such as these have proved to be attractive to end user operators and have helped Rotork Singapore to sell over sixty GO units during the last year.  As illustrated by this application, customer support in the country of final installation is also an important contributor to the success of Rotork’s products.  This actuator was inspected by engineers from PTT (Petroleum Authority of Thailand) at Rotork Thailand’s workshop, prior to site installation under Rotork supervision.

The PTT Gas Bangplee to Saraburi pipeline is 99 kilometres in length and a central element in Thailand’s growing natural gas transmission network.  Each block valve station on the pipeline network is equipped with a gas transmission control system, remotely supervised by SCADA systems at 24 hour-a-day operation centres.