Strandjacks

Strandjacks were developed in the early seventies. Meanwhile they are recognized as the most sophisticated lifting devices.

The principle

The strandjack lifting technique originates from the Concrete Post Tensioning Principle. A strandjack can be compared to a single-part winch.

In a strandjack a bundle of steel cables is guided through a hydraulic cylinder. Above and below the cylinder you will find an anchor system with a number of grips. Those grips can clamp the cable bundle. By stroking the cylinder in and out while the grips are engaged in the anchors a lifting or lowering movement is achieved.

The motion of the cylinders is driven by hydraulic power packs. They can be electric or diesel powered. A sophisticated software program synchronizes the motion of the strandjacks and adjusts the motion to the loads per lifting point. This program can operate and control up to 20 strandjacks simultaneously. During operation all loads and anchor positions are displayed on the screen of the control unit.

Technical basics

There are two types of strands used for lifting applications: a dyform of  15.7mm and one of 18mm. The 15.7mm strand can work with a dynamic load of 110kN. The 18mm strand can work with a dynamic load of 155kN. The number and type of strands used in a jack determine the safe working load of a jack. For lifting applications Hydrospex strandjacks are calculated with a 2.5 safety factor against breaking load to working load.

Strandjack applications

Hydrospex strandjacks are applied in the lifting industry, the offshore industry, the petrochemical industry and in marine salvage operations.

Buyers information

Hydrospex Strandjack Systems are available from 15 up to 850Te capacity. Units from 15 to 300Te can either be supplied from stock or be made and shipped in a short time. All systems are certified and tested under Lloyd’s whiteness. Each installation is delivered with an instruction and operation manual in English.