Bolts designed to shear at pre-determined tension

The "BreakBolt" is a unique safety fastener that is designed to deliberately shear at a predetermined tension level: first applications have been on umbilical risers in the North Sea and Nigeria

James Walker RotaBolt, world leaders in bolted joint technology and tension control, have successfully developed the "BreakBolt" - a unique safety fastener that is designed to deliberately shear at a predetermined tension level.

The new fasteners also incorporate the award winning RotaBolt technology, constantly and accurately measuring the tension across the bolted joint at the same time.

The BreakBolts have been supplied to Vetco and are currently being used on specific offshore well head applications where a breakaway potential was required as a primary safety feature in the design of the riser system.

The BreakBolt is engineered to shear at a pre-set ultimate tensile load and has a specially machined waist, which reduces the tensile stress area, allowing the bolt to break once it has reached the required tolerance.

The bolts are tested to destruction at an independent test house and are certificated to their desired break load.

"Designing a RotaBolt that would perform a controlled break under set conditions seemed a relatively straightforward task to begin with," commented Rod Corbett, managing director of RotaBolt, "but it has been a major learning curve and has taken a great deal of research and development to perfect the procedure.

We are delighted that the new BreakBolt not only incorporates all the advantages of our original technology so that it constantly monitors tension, but it also performs exactly as required, breaking away as specified under very challenging conditions".

The bolts have been supplied by Vetco as part of wellhead applications in the North Sea and in Nigeria.

Vetco clients had requested that the umbilical riser systems should have a break safety feature built into the design.

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