RotaBolt load indicating fasteners are modified bolts and studs that allow a specific tension to be applied. A finger-feel registering device – useable when wearing protective gloves or diving equipment – indicates achievement, maintenance or loss of the designed fastener tension.
A standard bolt or stud 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 load indicator fastener is stretched, internal air-gap 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 2 load indicator fastener provides an even greater range of tension control on installation tightening and in-service checking than RotaBolt 1, 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 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 at a distance 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 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 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. Where plant policy is to follow ASME PCC-1 guidance, then the Appendix M washer is an integral part of the route to compliance.