Posted to News on 16th Jul 2008, 00:00
Torque multiplier gives accurate subsea actuation
Norbar Torque tools has developed an innovative torque multiplier for the subsea tools market. Designed as an adapter to allow API 17D Class 4 intervention torque tools to generate the torque required to handle Class 7 applications, the new torque multiplier delivers a higher level of accuracy than alternative solutions, and increased flexibility in use through its added-value features and its ability to be configured in two standard lengths.
Gear adapters have become popular as a means of extending a Class 4 tool (which would generate up to 2,700Nm of torque) up to Class 7 (34,000Nm). To date, the trade-off for this added convenience has been accuracy, with extended Class 4 tools failing to offer the precise torques of dedicated Class 7 tools. But Norbar's innovative design has overcome this problem, enabling a Class 7 torque to be generated from a Class 4 torque input to an accuracy of better than +/-5 percent.
The function of the gear is to operate as a torque multiplier, but the ratios have to be exactly right to achieve the correct torque and the specified speed from the Class 4 tool. At the same time, the gear has to be able to function reliably in a subsea environment at extreme temperatures and pressures. It also has to be easy to handle. Norbar was able to meet all of these requirements.
The company's newly developed torque multiplier is designed to withstand the corrosive environment and is pressure compensated to allow operation at typical subsea pressures. It is designed to be suitable for use with the standard Class 4 torque tools that, operated by ROVs, are used to remotely actuate the wet valves. There is also a restriction on the weight that ROVs can manipulate so considerable design work has gone in to keeping the tool weight down to an acceptable level.
