🔍 Key Concepts

• Main propulsion steam turbine warm-up procedures and the need to avoid thermal shock • Function of ahead vs. astern throttle valves in controlling steam admission direction to the turbine • Purpose of bleed valves (HP/LP) in draining and warming lines versus driving the rotor

💭 Think About

• Ask yourself: when you want to start warming the rotor itself, do you send steam through a throttle that actually turns the turbine, or through a valve mainly used for line warming/drainage? • Which direction of rotation and which turbine casing (high pressure or low pressure) is normally brought up first during a controlled warm-up? • Consider which valve is designed for controlled, gradual admission of steam to the main turbine for normal ahead operation.

✅ Before You Answer

• Identify which components are primarily for drain/line warm-up (bleeds) versus throttle/operating control (ahead/astern valves). • Confirm standard practice: during initial warm-up, steam is usually admitted in the normal operating direction of rotation to prevent machinery damage. • Check that the chosen valve would allow slow, controlled opening to gently admit steam while monitoring speed, vibration, and temperature.