When using rotation-resistant ropes in boom hoisting reeving systems, the sheave pitch diameter must be a minimum of what ratio?

The correct choice specifies that the sheave pitch diameter must be a minimum of 18 times the diameter of the rotation-resistant rope being used in boom hoisting reeving systems. This requirement is crucial because it helps to prevent excessive wear and stress on the rope as it moves over the sheaves.

Rotation-resistant ropes are designed to reduce the likelihood of twisting, which can occur under load. By maintaining a proper sheave pitch diameter ratio, operators can ensure that the ropes have enough freedom of movement to function effectively without becoming entangled or damaged. The larger diameter allows for smoother operation and helps to prolong the rope's life by minimizing bending and crushing forces.

If the sheave diameter is too small relative to the rope diameter, it can lead to rapid degradation of the rope fibers, ultimately jeopardizing safety and operational efficiency. Therefore, adhering to the 18 times ratio ensures that the reeving system operates within safe and effective parameters, maintaining both equipment integrity and operational reliability.