USCG Exam PracticeMaintenance, machine tools, drawings, and tables
During steam turbine warm-up, what is the primary hazard associated with admitting steam to a cold turbine too rapidly, and what protective measure directly addresses it?
- A. Rapid steam admission causes condenser flooding; the low-vacuum alarm protects against this
- ✓ Uneven heating bows the rotor, causing destructive rubbing and vibration; slow warm-up with the turning gear engaged addresses thisCorrect
- C. Rapid steam admission causes lube-oil overheating; the gravity tank maintains oil flow to prevent bearing failure
- D. Thermal shock cracks the turbine casing; the overspeed trip shuts steam before rotor speed becomes excessive
Why B is correct
NAVEDTRA 14104 §5-2 states that uneven heating bows the rotor and causes destructive rubbing and vibration, and that a cold turbine must be warmed slowly and rolled to heat it evenly. The turning gear (jacking gear) keeps the rotor rotating slowly to ensure even heating whenever the turbine is hot but not in use.
Cited:NAVEDTRA 14104 §5-2