Lifting Block Load Sharing for Deep Water Depth Limits
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Solution Overview
Problem
Current lifting equipment in the oil industry faces limitations in depth range due to the self-weight of steel wires, which can reduce the lift capacity to zero, especially when handling heavy loads in deep water operations.
Innovation Solution
A method and apparatus that utilize a lifting block system with two lifting devices, allowing load sharing between a primary and secondary lifting device, with the first connection element bearing against the lifting block and the second connection element attaching to the secondary lifting device, enabling the load to be supported by both devices, thereby reducing the effective weight on the primary lifting device and extending the operating depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If steel wires are used as lifting medium to handle heavy loads, then lifting capacity is sufficient, but the self-weight of the wires significantly reduces the available lift capacity and limits operating depth
Solution Approach 1:
The lifting system is divided into two separate lifting devices (first and second lifting devices) that operate independently but coordinate to lift the same load. Each device handles a portion of the total load, effectively segmenting the lifting function to overcome the depth limitation imposed by wire self-weight in a single-system configuration.
Solution Approach 2:
Two lifting devices are combined to work together on a single load, merging their lifting capacities. The load is shared between both devices, allowing the system to achieve greater operating depth while maintaining sufficient lifting capacity that neither device alone could provide at such depths.
2Length of moving object
If synthetic fibre ropes are used to overcome self-weight limitation, then operating depth is extended, but specially designed winches are required and resonance problems arise due to elasticity
Solution Approach 1:
The invention uses conventional steel wire ropes with existing lifting devices rather than expensive specially designed winches required for synthetic fibres. The system accepts the self-weight limitation of steel wires but overcomes it through the two-device configuration, avoiding the need for costly specialized equipment while maintaining operational effectiveness.
3Length of moving object
If pennant wire is introduced to increase depth range, then operating depth is extended, but the rigging train complexity increases
Solution Approach 1:
Instead of adding pennant wire to extend the single lifting device's reach, the system segments the lifting function into two separate devices, each operating within their optimal depth ranges. This approach achieves extended effective depth range without complicating the rigging train of any single device.
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A lifting block and a method of using it for supporting a load (8) from a first lifting device (2) or sharing the load between the first lifting device (2) and a second lifting device (3), particularly for use on a vessel (1) and deep water applications. The lifting block (7), with at least one sheave (10), has first and second connection elements (14, 15) associated with it. In one arrangement (single fall) a lifting wire or rope (4) is fed around the sheave (10) and terminated in an end stop (14) which also provides the first connection element. When the first lifting device (2) is operated alone, the end stop (14) rests on the block (7). When the second connection element (15), secured to the lifting wire or rope (5) of a second lifting device (3), is joined to the first connection element (14) the load is snared between the two lifting devices (2, 3) which can then be operated in unison to position the load at a required, deeper position.