Rotating Locking Device Secondary Release Mechanism
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Solution Overview
Problem
Traditional locking mechanisms in subsea hydrocarbon drilling operations, such as those used in Christmas trees and subsea control modules, can fail due to corrosion or contamination, preventing the retrieval of subsea control modules for maintenance or repair.
Innovation Solution
A rotating locking device with a secondary release mechanism, featuring a locking arm, plunger, and load pin, which allows axial translation to engage a biasing profile and transition the load pin to a breakaway position, enabling decoupling of the locking arm from the locking head even if the device is stuck.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional nut-and-screw locking mechanism is used to resist separation forces, then the locking mechanism provides reliable locking, but corrosion or contamination may prevent the nut from unthreading and hinder retrieval
Solution Approach 1:
The locking mechanism is divided into two independent systems: a primary locking system (locking arm with load pin) and a secondary release system (plunger with biasing profile). The secondary system can independently activate to release the primary system, ensuring retrieval capability even if the primary system becomes stuck due to corrosion or contamination.
Solution Approach 2:
The plunger acts as an intermediary component that, when axially translated, engages the biasing profile to force the load pin out of the locking arm. This intermediary mechanism provides a controlled way to override the primary locking system without directly manipulating the stuck nut-and-screw arrangement.
2Strength
If a locking mechanism is designed to resist strong separation forces, then the locking strength is improved, but the device becomes more complex with additional components
Solution Approach 1:
The secondary release mechanism is integrated within the existing locking arm structure. The plunger is disposed inside the throughbore of the locking arm, and the biasing profile is formed on the plunger itself. This merging approach adds the release capability without requiring entirely separate external mechanisms, thus limiting the increase in overall device complexity.
3Duration of action of stationary object
If the locking arm is made robust to withstand subsea environmental conditions, then the durability is improved, but corrosion and contamination may still prevent normal unlocking operation
Solution Approach 1:
The biasing profile is pre-formed on the plunger, and the load pin is pre-positioned in the locking arm. When the plunger is axially translated (by rotating the lifting mandrel), the biasing profile automatically engages and forces the load pin out without requiring manual manipulation of the locking components. This preliminary arrangement of components enables automatic release action that overcomes corrosion or contamination issues.
Data Source
AI summary
A rotating locking device includes a locking arm, including a throughbore, coupled to a housing and axially rotatable relative to the housing. The rotating locking device also includes a plunger including a biasing profile disposed within the throughbore and a locking head coupled to a distal end of the locking arm, the locking head including a recess to at least partially receive the distal end of the locking arm. The rotating locking device further comprises a load pin that couples the locking head to the distal end of the locking arm and is configured to resist separation of the locking head and the locking arm when in a securing position. Axial translation of the plunger causes the biasing profile to engage the load pin and cause the load pin to transition to a breakaway position.