Turbines often have segmental carbon ring sealing glands that are held in place by

• A. Set screws
• B. Woodruff keys
• C. Oil pressure
• D. Garter springs

Answer: (D)

The key idea is that segmental carbon ring sealing glands need a way to apply even, continuous pressure around the entire circumference while allowing for movement from thermal expansion and wear. Garter springs provide that function. They are placed around the outside of the sealing segments and exert a constant radial force, clamping the carbon ring segments together and against the seal surface. This keeps the seal seated and maintains tight contact as temperatures rise and the rings wear, without relying on rigid fasteners that could create uneven loading or loosen over time.

Rigid set screws would produce point pressures and can loosen with vibration, disrupting the seal. Woodruff keys are meant for torque transmission between rotating parts and wouldn’t hold the ring circumferentially. Oil pressure might contribute to sealing in some designs, but it cannot reliably hold the segments in place under varying operating conditions, especially when oil pressure fluctuates or drops. Garter springs uniquely provide the continuous, adaptable retention needed for these seals.