In the early years of North Sea development, torque tools used in factories, refineries and offshore or subsea operations were generally modifications of standard models. It wasn’t long before specific oil and gas torque tools were brought to market, with Norbar one of the pioneers.
Nowadays, a wide variety of torque tools are used for actuation and measurement at offshore and subsea locations, frequently manipulated using remote operated vehicles (ROVs). Robotics has revolutionised the range and scope of projects that can be undertaken in a hostile deep water environment, such as the challenging undersea terrain encountered in the construction of the Langeled pipeline which links the Norwegian Ormen Lange gas field to the UK.
There are a number of issues surrounding the use of torque multipliers in deep sea applications. The first issue is robustness. With Langeled, for example, the fasteners securing the pipe sections had to be tightened to a precise torque using a calibrated instrument which required a torque multiplier that was sufficiently robust to work on pipeline connection points.
Secondly, accuracy is very important. Working at extreme depths and sub-zero temperatures means tools have to generate a high level of torque with total accuracy. This would normally require a substantial steel-bodied instrument, but this is not possible with ROVs which have a maximum payload of 60kg when immersed in sea water.
Which brings us to our third issue, namely weight. Minimising weight is a critical consideration in the manufacture of torque instruments for use by ROVs. Increases in weight mean that more buoyancy is required on the ROV, which leads to increased costs and impaired manoeuvrability. Materials therefore need to be chosen for lightness while being able to deliver on the required strength and torque.
Norbar has engineered numerous customised torque multiplier tools, up to 300,000 N·m, specifically for the oil and gas industry and in both aluminium and steel. Norbar’s oil and gas torque multiplier has been so successful that it is now the torque multiplier of choice for many in the industry.
By Mark Woodward, Technical Manager.