22 August 2014
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Measurement fasteners do it underwater

One of the major benefits of RotaBolt's measurement technology is its ease of use. In maintenance, it only requires a finger and thumb 'instant' check to see if the RotaCap is still locked on the head of the bolt indicating that the correct tension is being maintained across the joint, the James Walker Group company claims.

However matters become slightly more complex if the maintenance check is underwater and you are wearing a diver's suit complete with neoprene gloves.

RotaBolts have been used on subsea pipelines and platform installations since the mid-1980s and it wasn't long before the difficulty of checking for correct tension with heavy gloves surfaced as an issue. It was still possible to carry out the checks, and they were still much quicker than conventional systems, but it presented a challenge to the technical team at RotaBolt to see if they could overcome the problem and come up with an innovative solution.

The RotaBolt Divers Wheel proved a viable solution. The tool is a female checking device which is manufactured to fit over the different sizes of RotaBolt indicator cap and is made up of four essential components: a nose piece containing the form of the indicator cap; a body which is gripped by the operator; and a ball bearing and spring assembly that provides the required ratchet operation to indicate when the RotaCap indicator on the head of the fastener is locked meaning the bolt is at the correct design tension level setting.

All Divers Wheels are in-house calibrated to a specific resistance force of 21 to 28N.cm before they ratchet. This force was derived from hundreds of physical tests measuring the force applied, on a torque meter, from the finger and thumb grip applied by several different personnel.

This ensured that the Divers Wheel emulates the physical finger and thumb grip operation which is a standard feature/check of a RotaBolt.

As the RotaBolt is tightened the Divers Wheel, which is now engaged on the RotaCap, is lightly rotated. At the point when the RotaCap locks the will ratchet-click on the ball bearing/spring mechanism providing a very simple, accurate and effective physical indication felt by the operator that the bolt design tension setting has been achieved.

Paul Gay

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Related Companies

James Walker RotaBolt Ltd

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