The correct size raising line is critical to ensure safe raising and lowering of the mast and substructure. Using the proper size line increases the longevity of the entire raising system and optimizes the life span of the line and sheaves. Using an improper size may result in raising system failure causing catastrophic results.
Following are the most common properties to consider when selecting a raising line for mast and substructure;
Rope Strength
Raising rope must be fabricated from IWRC ropes. The published rope capacity is considered for new, unused rope. A rope should never be considered for its full strength for operation. During its useful life, a rope loses strength gradually due to natural causes such as surface wear and metal fatigue. The minimum breaking force for a rope must be divided by the appropriate design factor in order to determine the allowable load on the rope for mast raising or lowering.
Fatigue Resistance
Fatigue resistance involves fatigue of the wires that make up a rope. To have high fatigue resistance, wires must be capable of bending repeatedly under stress – passes over a sheave during operation. Increased fatigue resistance is achieved in a rope design by using a large numbers of small diameter wires due to their ability to bend as the rope passes over sheaves. To overcome the effects of fatigue, ropes must never bend over sheaves with a diameter so small that it bends the wires excessively.
Crushing Resistance
Crushing is the effect of external pressure on a rope, which damages it by distorting the cross-section shape of the rope, its strands and core. When a rope is damaged by crushing, the wires, strands and core are prevented from moving and adjusting normally during operation. Compacted-strand ropes are more crushing resistant than standard round-strand ropes.
Resistance to Metal Loss and Deformation
Metal loss refers to the actual wearing away of metal from the outer wires of a rope, and metal deformation is the changing of the shape of outer wires of a rope. This reduces rope strength.
Resistance to Rotation
During mast raising and/or lowering, torque is created within the raising line as wires and strands try to straighten out. The raising line is designed to operate with this mast raising-lowering induced torque.
With locations in both the KSA and UAE, Lee C. Moore, A Woolslayer Company alongside our partner, United Caravan Trading and Contracting is ready to serve our Middle East customers. Bridle/Raising lines are just one of the many products we manufacture, in addition to our field service and inspection capabilities.
Please contact Contact Casey Halford +966-55-885-7448 or Jerry Murray +966-53-380-6378 for your next project or for additional information. Or email us at ksa-ops@lcm-wci.com.
