A wide variety of torque tools are used for actuation and measurement at offshore and subsea locations, frequently manipulated using robotic vehicles or ROVs. Robotics has revolutionised the range and scope of projects that can be undertaken in a hostile deepwater environment such as the challenging undersea terrain encountered in the construction of the Langeled pipeline.
The 1200km pipeline links the Norwegian Ormen Lange gas field to the UK and can supply approximately 2 billion cubic metres of gas annually when in full production. Ormen Lange was the first offshore gas field where all production stations were located on the seabed and the 1m diameter gas pipes cross an incredibly rough seabed terrain, requiring complex routing past underwater peaks, rockfields and gulleys.
At each junction, fasteners securing the pipe sections had to be tightened to a precise torque using a calibrated instrument. The specification required a torque multiplier that was sufficiently robust to work on pipeline connection points, each located at a terminator platform where the flow could be shut at need to repair the system.
Working at extreme depths of up to 1500m and at sub-zero temperatures, the tool had to generate a high level of torque with total accuracy to actuate the wet pipe connector clamps. This would normally require a substantial steel-bodied instrument, but this was out of the question, since the device needed to be light enough to be carried by an ROV with a maximum payload of 60kg when immersed in sea water.
The solution was to manufacture a customised torque multiplier, meeting the required torque up to 63,000Nm and constructed of high strength aluminium to accommodate the weight limit for a standard ROV. Manipulator handles allow for both vertical and horizontal operation and the device has been successfully in service since 2005.
Torque tools for offshore and subsea applications are required to comply with the international oil and gas industry standard ISO 13628 -8:2002(E), which includes the rotary torque standard. As well as wet pipe connector clamp tools such as used for Langeled, Norbar’s portfolio includes valve intervention tools, wet intervention torque multipliers plus torque multipliers and transducers for use in intervention tools, including gearboxes with or without integral torque transducers.
For more information:
Norbar Torque Tools NZ Ltd
Tel: 09 579 8653
Email: [email protected]