CASAR - Special Wire Ropes

CASAR Drahtseilwerk Saar GmbH is a manufacturer of rotation-resistant special steel wire ropes for cranes and other offshore devices, including pull-in-risers and riser-tensioners.

Since its founding in Germany in 1948, CASAR has stood for innovative product developments. With qualified products, the company has an increasing production capacity to fulfil market requirements. To remain at the forefront, investment continues in new technologies to improve products and technical facilities. The company is accredited to ISO EN 9001.

STARLIFT - ROTATION RESISTANT SPECIAL WIRE ROPE

In a conventional rope, an external load creates a moment which tries to untwist the rope and rotate the load. A rotation-resistant CASAR special wire rope such as the Starlift does not show any tendency to untwist even when loaded to the safe working load of the application. They have a steel core which is an independent rope, closed in the opposite direction to the outer strands. Under load, the core tries to twist the rope in the one direction, the outer strands try to twist it in the opposite direction. The geometrical design of a rotation-resistant CASAR special wire rope is such that the moments in the core and the outer strands compensate each other. Even with great lifting heights no rope twist occurs.

In single fall operations the use of non-rotating ropes is mandatory for lifting of unguided loads. For multiple fall operations non rotation-resistant ropes achieve a higher service life than rotation-resistant ropes when operating under identical conditions. Because of their larger strand diameter, non rotation-resistant ropes are more robust and have lower tendency to birdcage under twisting forces caused by large fleet angles.

With no specific conditions that require the use of rotation-resistant ropes, non rotation-resistant ropes should be used in multiple fall loads. But under certain geometric loads there is danger that the falls could cable whilst underload. This is most likely with great lifting heights or under the influence of additional moments created by wind or the slewing of the crane. In such a situation, rotation-resistant ropes, or pairs of left and right hand lay non rotation-resistant ropes should be used.

If a crane is supplied with rotation-resistant ropes by the manufacturer, subsequent replacement should always be rotation-resistant.

PLASTIC LAYER ROPES

Ropes with a plastic layer between the steel core and the outer strands combine the advantages of a fibre core (the soft bed for outer strands) with the benefits offered by full steel ropes. The plastic layer forms a custom moulded cushion layer for the outer strands. This fixes the elements of the rope in relation to each other, acting rather like a corset which maintains rope stability, even under the highest external forces. The most effective remedy against birdcaging is to use a CASAR Special Wire Rope with an internal plastic layer. By sealing the core, the plastic traps lubricant and ensures a maintenance free core with lifetime lubrication. At the same time it also excludes water and abrasive elements that could penetrate conventional ropes.

BREAKING LOADS AND SAFETY

CASAR special wire ropes have highest breaking loads, giving the user a high factor of safety. The ropes are designed by a combination of various technologies:

• A large number of strands increasing the metallic area of the rope
• A plastic layer reducing internal stresses
• Compacted strands increasing the fill factor of the rope elements
• Parallel lay leads to a more compacted rope construction

ADVANTAGES

CASAR special wire ropes offer the user the following advantages:

• Design advantages by reducing the sheave and drum diameters and the size of motor and gearbox; thereby cost-reduction already in the construction process of new units
• Increased safety
• Longer service life due to lower specific stress on the rope
• Ideal cost efficiency
• Ideal return on investment

CASAR special wire ropes' service life is up to three times longer than that of conventional wire ropes! CASAR is world-wide well represented through a number of partners in various countries.

REFERENCES

CASAR supplies the following companies, amongst others, with its special wire ropes: Agip, Amoco, BP, Conoco, ELF, Ferrostaal, Kenz, Liebherr, MacGregor, Petrobras, Shell and Stalprodukter.