When starting a steam turbine it is customary practice to

• A. First, rotate the shaft by hand to see if it turns freely.
• B. Check the lube oil and start the lube oil cooler before starting the turbine.
• C. Close the turbine casing drains and steam trap bypasses until the turbine is fully warmed.
• D. Overspeed the turbine to test the operation of the overspeed trip, before continuing with the turbine warm-up.

Answer: (B)

Proper pre-start preparation for a steam turbine centers on getting the lubrication and cooling systems up and ready before any rotation. The lube oil system must be circulating, with oil pressurized and at the correct temperature and viscosity so the bearings and gears are protected from metal-to-metal contact and excessive wear as soon as the shaft turns. Starting the lube oil cooler before the turbine begins to rotate ensures the oil isn’t too hot and is maintained at the right viscosity throughout the warm-up, which helps prevent overheating and reduces bearing stress during the initial run.

Rationale for not doing other options: turning the shaft by hand is unsafe and not a routine or reliable way to verify readiness. Closing casing drains and steam trap bypasses until the turbine is warmed can trap condensate and disrupt proper drainage and venting, leading to pressure and moisture issues. Overspeed testing before warm-up is hazardous and not part of normal startup practice; overspeed protection is tested under controlled conditions and separate from the standard warm-up sequence.