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A Condition-Based Maintenance Concept for CALM Buoy Bearings and Swivels to Improve Offshore Crude Export Availability
Subject area: Science,Engineering and Technology · Area of research: Buoy Bearings and Swivels
DOI: https://doi.org/10.64388/IREV2I6-1722579
Abstract
Catenary Anchor Leg Mooring (CALM) buoys remain the dominant terminal solution for offshore crude oil export in many producing regions, particularly in West Africa, the Middle East, and Southeast Asia. The availability of a CALM terminal is governed to a large extent by two rotating subsystems: the main bearing, which allows the buoy turntable to weathervane with the moored tanker, and the fluid swivel, which transfers crude oil from the geostatic piping to the rotating product path. Failures of these components are infrequent but highly consequential, since repair typically requires demobilisation of the export system, specialist offshore intervention, and in severe cases dry transport of the buoy to a repair yard. This paper presents a condition-based maintenance (CBM) concept, formulated in 2018, for the main bearing and product swivel of CALM buoys. The concept replaces the prevailing calendar-based and dive-inspection-driven maintenance philosophy with continuous condition monitoring built around rotational torque trending, vibration and acoustic emission measurement, grease and wear-debris analysis, seal cavity pressure monitoring, and temperature surveillance, integrated through an ISO 13374-aligned data processing architecture. A failure mode analysis is used to map each dominant degradation mechanism to at least one measurable condition indicator, and an availability assessment is developed to quantify the benefit of early fault detection against the baseline of run-to-failure and periodic overhaul strategies. The analysis indicates that a well-instrumented CBM programme can materially reduce unplanned terminal downtime, extend the interval between major interventions, and convert emergency repairs into planned campaigns aligned with tanker scheduling windows. Implementation considerations for unmanned, power-limited, hazardous-area buoy environments are discussed, together with the organisational and data management prerequisites for a successful deployment.
Keywords
CALM buoy, single point mooring, condition-based maintenance, main bearing, fluid swivel, availability, offshore crude export, condition monitoring, prognostics.
How to cite this paper
@article{1722579,
author = {Paul Chibuike Obetta, Nwakamma Ninduwezuor-Ehiobu},
title = {A Condition-Based Maintenance Concept for CALM Buoy Bearings and Swivels to Improve Offshore Crude Export Availability},
journal = {Iconic Research And Engineering Journals},
year = {2018},
volume = {2},
number = {6},
pages = {385-410},
issn = {2456-8880},
url = {https://www.irejournals.com/formatedpaper/1722579.pdf},
abstract = {Catenary Anchor Leg Mooring (CALM) buoys remain the dominant terminal solution for offshore crude oil export in many producing regions, particularly in West Africa, the Middle East, and Southeast Asia. The availability of a CALM terminal is governed to a large extent by two rotating subsystems: the main bearing, which allows the buoy turntable to weathervane with the moored tanker, and the fluid swivel, which transfers crude oil from the geostatic piping to the rotating product path. Failures of these components are infrequent but highly consequential, since repair typically requires demobilisation of the export system, specialist offshore intervention, and in severe cases dry transport of the buoy to a repair yard. This paper presents a condition-based maintenance (CBM) concept, formulated in 2018, for the main bearing and product swivel of CALM buoys. The concept replaces the prevailing calendar-based and dive-inspection-driven maintenance philosophy with continuous condition monitoring built around rotational torque trending, vibration and acoustic emission measurement, grease and wear-debris analysis, seal cavity pressure monitoring, and temperature surveillance, integrated through an ISO 13374-aligned data processing architecture. A failure mode analysis is used to map each dominant degradation mechanism to at least one measurable condition indicator, and an availability assessment is developed to quantify the benefit of early fault detection against the baseline of run-to-failure and periodic overhaul strategies. The analysis indicates that a well-instrumented CBM programme can materially reduce unplanned terminal downtime, extend the interval between major interventions, and convert emergency repairs into planned campaigns aligned with tanker scheduling windows. Implementation considerations for unmanned, power-limited, hazardous-area buoy environments are discussed, together with the organisational and data management prerequisites for a successful deployment.},
keywords = {CALM buoy, single point mooring, condition-based maintenance, main bearing, fluid swivel, availability, offshore crude export, condition monitoring, prognostics.},
month = {December},
doi = {https://doi.org/10.64388/IREV2I6-1722579}
}