Replaceable Turret Roller Bearing Assembly for In-Situ Repair
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Solution Overview
Problem
Existing turret bearing systems for offshore vessels, particularly those using three-row roller bearings, are not easily replaceable in situ, leading to high costs and operational risks due to the need for expensive disassembly and replacement processes, and challenges in maintaining radial load balance during replacement.
Innovation Solution
A three-row roller bearing assembly design that allows for the replacement of wearable rolling elements and races in situ, utilizing replaceable hardened steel race inserts and a secondary radial bearing to maintain radial load balance, with a jacking system to lift the turret and facilitate access for replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-row roller bearings are used in turret systems, then reliability is improved, but ease of repair deteriorates because the bearings cannot be replaced in situ
Solution Approach 1:
The bearing assembly is divided into separable components: the outer ring assembly remains fixed while the inner ring assembly with rolling elements can be removed and replaced independently. The inner ring assembly includes the inner ring, rolling elements, and cage as a removable unit, allowing in-situ replacement without removing the entire bearing assembly from the turret system.
Solution Approach 2:
The inner ring assembly containing the rolling elements is extracted as a separate replaceable component from the outer ring assembly. This extraction allows the rolling elements to be replaced in situ by removing only the inner ring assembly, transporting it to a shipyard for maintenance, and reinstalling a refurbished or new assembly.
2Ease of repair
If the bearing assembly is disassembled for rolling element replacement, then ease of repair is improved, but device complexity increases due to the need for precise reassembly
Solution Approach 1:
Alignment features such as dowel pins and machined surfaces are pre-installed on the outer ring assembly before the inner ring assembly is removed. These pre-prepared alignment features guide the precise reinstallation of the inner ring assembly, ensuring correct positioning without requiring complex measurement or adjustment procedures during reassembly.
Solution Approach 2:
The complex mechanical alignment process is replaced by using precision-machined mating surfaces and dowel pin locators that automatically guide the inner ring assembly into correct position during reinstallation. This mechanical guidance system eliminates the need for complex alignment procedures, special tools, or skilled manual adjustment.
3Ease of repair
If the turret is lifted to access support rollers, then ease of repair is improved, but weight of moving object increases due to lifting requirements
Solution Approach 1:
The load-bearing function is extracted from the support rollers during replacement operations. The turret is temporarily lifted only enough to remove the inner ring assembly and support rollers, not to fully raise the turret. The lifting load is minimized to only what is necessary to clear the rollers for removal, rather than lifting the entire turret weight for maintenance access.
4Ease of repair
If radial rollers are removed for replacement, then ease of repair is improved, but stability deteriorates due to loss of radial load balance
Solution Approach 1:
The turret is temporarily supported by alternative means (such as hydraulic jacks or temporary bearing supports) before the radial rollers are removed. This preliminary support action maintains radial load balance and turret stability during the roller replacement process, preventing unbalanced loads that could cause misalignment or damage to the bearing races.
Data Source
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AI summary
An arrangement for in situ remediation of a bearing assembly rotatively coupling a vessel to a turret about its longitudinal axis. An inner ring assembly is coupled to the turret and an outer ring assembly is coupled to the vessel. A support row assembly connected between the inner and outer ring assemblies allows rotation of the outer ring assembly with respect to the inner ring assembly and axially transfers the turret weight to the vessel. A radial row assembly and a centralizer are disposed between the inner and outer ring assemblies. The radial row assembly normally transfers radial load from the vessel to the turret and the centralizer has a radial clearance with the outer ring assembly. During in situ repair of the radial or support row assembly the centralizer transfers radial load from the vessel to the turret and maintains substantial concentricity of the inner and outer ring assemblies.