Amidst a concerning rise in propeller shaft bearing damage, particularly on older vessels using environmentally acceptable lubricants (EALs), this newsletter addresses the emerging trends, potential causes, and essential safeguards for the maritime industry. The dnv source.
- Increasing cases of propeller shaft bearing damage on older vessels using environmentally acceptable lubricants (EALs) prompt concerns and require preventative measures.
- Potential causes of damage include contaminated lubricants, reduced design margins, operational factors, and challenges posed by EALs in aft sealing arrangements.
- Periodic verification of shaft sealing arrangement integrity, as recommended by DNV rules, is crucial for protecting both bearings and the environment in the face of these challenges.
Emerging Trends in Propeller Shaft Bearing Damage
Recent operational data points to a concerning uptick in reported damages to propeller shaft bearings, particularly affecting older vessels aged over a decade. These vessels are operating with environmentally acceptable lubricants (EALs), and this technical news sheds light on this growing issue, offering insights on mitigating propulsion safety risks and preventing costly damages.
Probable Causes of Bearing Damage
This article explores the probable causes behind the observed damages, which include partial or complete wiping of aft bearings, often accompanied by leaking propeller shaft aft seals. It delves into factors such as continued operation with contaminated lubricants, design and operational margins, shaft alignment sensitivity, and operational conditions, highlighting their contributions to bearing deterioration.
Challenges with EALs and Aft Sealing Arrangements
One significant challenge lies in the aft sealing arrangement. Operating with EALs introduces the risk of biodegradation and accelerated lubricant deterioration in the tiny barrier chamber space between sealing rings. This deterioration can affect the compatibility of sealing ring materials, potentially leading to damage and water contamination of the main stern tube bearing lubricant system.
Ensuring Shaft Sealing Arrangement Integrity
To prevent such issues, it’s crucial to periodically verify the tightness of the shaft sealing arrangement, a practice included in DNV rules as part of bottom and propeller shaft-related surveys. This proactive approach helps maintain the integrity of the system, safeguarding both the bearings and the environment.
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