A ball valve is designed to be 100% open or 100% closed.

A globe valve can be throttled to adjust the flow rate. A ball valve would be damaged being partially open.

Ball valves share a small obstruction of its fluid and a lower operating sound;
Such kinds of valves possess a simple structure without any restrictions of its installment, a small relative volume, a light weight and a undemanding repairing;
The medium of ball valves take a divergent flowing without any vibrations;
Ball valves take a high accuracy of its processing with an expensive cost;
Throttling doesn’t belongs to the ball valve’s employment.

Ball valves are durable, performing well after many cycles; and reliable, closing securely even after long-term of misusing. On the flip side, ball valves lacking the fine-controlling in the throttling applications offered by globe valves.

The ball valves are probably the best valves for isolation purpose. Since their sealing surface hardly comes in contact with the flow of steam.