Behavior of marine thruster lip seals under typical operating conditions

Marine thruster lip seals pose a condition monitoring challenge, yet they are seldom studied tribologically. The present work studies the behavior of a 300 mm diameter NBR marine thruster lip seal (n = 3) under typical operating conditions. Frictional torque and subsurface temperature were measured under 27 combinations of oil temperature, oil pressure, and rotational speed. The frictional torque increased with increasing oil pressure and decreased with increasing oil temperature. The subsurface temperature increased with increasing oil temperature, oil pressure, and rotational speed. There was no clear relation between the frictional torque and subsurface temperature. The frictional torque ranged 9.6–14.4 Nm, and subsurface temperature 57–94 °C. Preliminary wear measurements showed a wear track width of 0.2–0.3 mm and a wear rate of 0.031 ± 0.001 mm³/hour.