Corrugated Energizing Ring for Wellhead Locking
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Solution Overview
Problem
Current wellhead systems face issues with relative axial movement between concentric tubular members due to high pressures and thermal expansion, leading to wear and potential loss of integrity, and existing energizing rings often fail to provide sufficient locking forces or a predictable set position, requiring additional tools and devices.
Innovation Solution
A corrugated energizing ring with a positive stop mechanism that ensures contact between lock ring flanks through the stack-up tolerance range, eliminating the need for additional lockdown devices and providing a reliable interference fit to maintain the set position without excessive setting loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a straight engaging surface is used on the energizing ring, then the structure is simple, but the locking force is insufficient and relative axial movement cannot be prevented
Solution Approach 1:
The energizing ring incorporates a corrugated profile with curved engagement surfaces instead of straight surfaces. The corrugated shape creates mechanical interlocking with the lock ring, generating sufficient radial interference and locking force to prevent relative axial movement between wellhead members while maintaining structural simplicity
2Reliability
If a tapered energizing ring is used to ensure contact throughout stack up tolerance range, then locking reliability is improved, but an additional lock down device is required increasing complexity
Solution Approach 1:
The corrugated energizing ring is designed to self-lock within the lock ring through its corrugated profile. The mechanical interlocking geometry automatically maintains engagement and prevents reverse movement without requiring separate locking mechanisms or additional lockdown devices, thereby improving reliability while reducing system complexity
3Reliability
If increased radial interference is applied to ensure lock ring contact, then locking force is sufficient, but setting load limits are exceeded
Solution Approach 1:
The corrugated profile distributes the locking force through its geometric shape rather than relying on high magnitude radial interference. The curved engagement surfaces create mechanical advantage, achieving sufficient locking force with moderate setting loads that remain within operational limits
4Ease of operation
If the energizing ring position is not controlled, then installation is simple, but the set position is unpredictable reducing precision
Solution Approach 1:
The corrugated energizing ring features a self-positioning mechanism where the corrugated profile automatically engages with corresponding features on the lock ring at a predetermined position. This self-aligning geometry ensures accurate set position without requiring complex positioning controls or additional adjustment procedures, maintaining installation simplicity while achieving precise positioning
Data Source
AI summary
A wellhead assembly includes first and second wellhead members. An annular lock groove is located on an inner or an outer diameter surface of the first wellhead member. An annular lock ring is supported on an annular shoulder of the second wellhead member and is radially moveable between an unset position and a set position where a locking profile of the annular lock ring engages the annular lock groove. The second wellhead member is positioned concentrically with the first wellhead member, defining an annulus between the first and second wellhead members. An energizing ring is positioned in the annulus and axially movable between an unengaged position and an engaged position. The energizing ring has an engaging portion with a corrugated shape in cross section that is interference fit between the annular lock ring and the second wellhead member when the energizing ring is in the engaged position.