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One of the things I enjoy most about my job is being a UK delegate for international standards development.
In the early 1980s my father Ian became involved with BSI (British Standards Institution), the national business standards body for the UK and I continued after he retired. Currently I am involved with two ISO (International Standards Organisation) committees to revise torque tool standards and both have had meetings in the last week.
On Monday we continued the revision of ISO 6789 2003 which has the wonderfully descriptive but rather elongated title: ‘Assembly tools for screws and nuts -- Hand torque tools -- Requirements for design conformance testing, quality conformance testing and recalibration procedure’. The Working Group is largely comprised of torque wrench manufacturers from around the world. Some fellow committee members I have known for 20 years. We know and respect each other and that really helps when we have different views on the standards, because it is easier to give way ...
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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 ...
Although many methods exist to join two or more parts together, the ease of assembly and disassembly provided by threaded fasteners make them the ideal choice for many applications. The object of a threaded fastener, such as a bolt, is to clamp parts together with a tension greater than the external forces trying to separate them. The bolt then remains under constant stress and is immune from fatigue under normal circumstances.
Why then, I hear you ask don’t we just tighten our bolts as much as we possibly can? No chance of anything coming apart then.
Unfortunately, it isn’t that simple. If the initial tension is too high, the tightening process may cause bolt failure. If that bolt is holding a wheel onto a Formula 1 car the consequences are obvious. Equally, if the tension is too low, varying loads act on the bolt and it will also quickly fail.
There is therefore an optimum tension and the most reliable way of ensur ...
Norbar has devised easy-to-use online calculators that support the correct application of torque in three key areas:
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