Many operators no longer use limit switches for control of Xmas tree valves as they are considered unreliable and unsuitable; limit switch technology only provides valve status as fully open or fully closed with no continuous feedback.
To compensate for this, an alternative method has been to infer the position of the valve by trending the pressure in the hydraulic lines. However, accuracy of the pressure measurement versus valve position is poor, as is reliability, due to transmitter blockages that require maintenance.
The consequences of incorrect valve position control can include process failures, shutdown and most importantly impact on a safe working environment. Such loss of production can incur massive costs.
For a continuous direct valve position measurement, ABLE have developed a universal valve position transmitter (v-Trakka) which can be retrofitted to most leading types of surface Xmas tree valves to provide an accurate and repeatable 4-20mA output correlating to the actual physical valve position.
Once installed, the v-Trakka requires no maintenance. The v-Trakka is a compact, lightweight mechanical instrument suitable for installation in the harsh well environment. The 316 st/ st cover and rigid base provides significant protection from dirt and everyday impacts. The cover also provides added safety by preventing personnel from standing in front of the valve stem. The high-viz position marker can be viewed through the toughened-glass window slots.
In order to facilitate installation across the myriad of Xmas tree valve designs v-Trakka is available in two variants. Model VT1 for continuous direct valve position measurement on valves that have a central stem and Model VT2 for applications involving top side trees that use the indicator window design.