What is the maximum included angle for cables or chains used to lift a tank?

The maximum included angle for cables or chains used to lift a tank being 30 degrees is significant for safety and efficiency reasons. When chains or cables are used to lift heavy objects like tanks, the angle at which they are positioned can greatly affect the distribution of force. At steeper angles, there is an increased risk of the force pulling the lifting equipment off-axis, which could lead to equipment failure or loss of control of the load being lifted.

30 degrees is considered the ideal angle as it strikes a balance between minimizing stress on the lifting apparatus and ensuring maximum lift capability. Angles steeper than 30 degrees can lead to an increase in the horizontal component of the force, which might result in swaying or tipping of the load. In the context of lifting heavy objects like tanks, adhering to this angle is crucial to maintaining safety protocols and ensuring that the lifting operation is conducted as smoothly as possible.

The other options represent angles that are either too steep or too shallow, which can lead to unsafe lifting conditions. Thus, 30 degrees is set as the standard maximum for lifting operations involving chains or cables in tank lifting scenarios.