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Tension Control Bolting

RotaBolt® - Assurance through measurement

RotaBolt90% of all bolted joint failures can be attributed to low bolt tension on installation tightening. Achieving and maintaining the correct installed design tension will eliminate failures from fatigue, vibration loosening, structural slip and pressure containment.

Bolted joint reliability technology is an established science but the vast majority of bolted joints in engineering are tightened in an uncontrolled manner; the bolt tension achieved at the end of the tightening cycle is unmeasured and unknown.

RotaBolt technology is the science of measurement, it accurately measures tension so that it can be correctly achieved, maintained and monitored. With the right joint design, component quality and installed tension, integrity of the bolted joint is assured.

RotaBolt 1RotaBolt 1
A standard bolt is converted with a RotaBolt indicator and RotaCap. Component materials are compatible with the parent bolt to nullify in-service thermal and galvanic effects. It is 100% load test calibrated with an accuracy of ±5%. As the fastener is stretched under load, internal airgap technology locks the RotaCap at the specified, load test calibrated tension value. As soon as tension reduces, the RotaCap immediately rotates freely, to give a clear indication of tension loss.

RotaBolt 2RotaBolt 2
RotaBolt 2 provides an even greater range of tension control on installation tightening and in-service checking, by offering two tension settings in a single sensor. A dual load indicator cap has an outer cap for high tension setting, and an inner cap for low tension, giving the choice of an operational tension range, either for overload or maintenance control.

RotaBolt VisionRotaBolt Vision
RotaBolt Vision gives a clear, visual indication of loss of tension across the bolted joint. Using the same internal air-gap technology, it has a specially developed indicator which appears as an unbroken yellow line across the head of the fastener. As soon as any tension is lost, the load indicator fastener instantly rotates by ninety degrees to show a distinct right angle break in the yellow line. This is clearly visible up to 25 metres away and is ideally suited for locations where access is restricted and close inspection difficult.

Breakbolt successfully delivers an accurate breakaway mechanism as a primary safety feature and has been used on specialist sub-sea applications. The Breakbolts are engineered to break at a pre-set Ultimate Tension Stress (UTS). They have a specially machined waist, which reduces the cross sectional area, allowing the bolt to shear once it has reached the necessary tolerance. The bolts are tested to destruction at an independent test house and are certificated to their desired UTS.

Indicating Rod BoltIndicating Rod Bolt
RotaBolt technology has been applied to the standard Indicating Rod Bolt outlined in ASME PCC-1-2000, to develop new bolts which are a generational step forward. An Indicating Rod Bolt uses direct length measurement to gauge the delivery of load. The RotaBolt version gives a highly accurate measurement of bolt tension from the length extension to guarantee the uniform delivery and maintenance of load. Bolts are individually 100% load test calibrated and fitted with a special indicator to measure extension. Every bolt’s extension measurement is individually certified.

ASME PCC-1 WashersASME PCC-1 Washers
Where RotaBolts are being used in pressure boundary applications or as part of an ASME PCC-1 plant regime, then ASME PCC-1 Appendix M Washers are recommended, as these are specifically designed for pressure boundary bolted flanged connections. ASME washers take into consideration fastener dimensions, diameters and material operating conditions specifically used in pressure boundary flange joints. The material used for the ASME washers is also the same as the material used to manufacture the fasteners; it therefore has the same mechanical and chemical properties.

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