Wedge Threadform Relief Spaces to Prevent Hydraulic Locking
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Solution Overview
Problem
Existing tubular connectors in the oil and gas industry face challenges in accommodating sufficient thread compound volume, leading to hydraulic locking and premature connection failure due to insufficient voids, which affects torque readings and assembly/disassembly accuracy.
Innovation Solution
Designing a tubular connection threadform with thread compound relief spaces extending along the entire axial length, creating a continuous void between crests and roots to accommodate more thread compound, enhancing flexibility and ease of machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thread compound volume is increased to improve lubrication and filling, then assembly quality improves, but hydraulic locking occurs causing inaccurate torque readings
Solution Approach 1:
The threadform is segmented into distinct zones: engagement areas where threads contact to transmit load, and relief areas where thread compound is contained. This segmentation allows the compound to be distributed in controlled portions along the axial length, preventing accumulation that would cause hydraulic locking while ensuring adequate lubrication in critical zones.
Solution Approach 2:
Different regions of the threadform are given different properties: engagement areas have precise dimensional tolerances for load transmission, while relief areas have modified geometry (reduced crest height or increased root depth) to create void space. This local differentiation allows the same threadform to simultaneously achieve accurate torque readings in engagement zones and adequate compound containment in relief zones.
2Quantity of substance
If voids are created to contain thread compound, then compound retention improves, but connection strength may be reduced due to reduced material
Solution Approach 1:
The threadform is divided into engagement areas that maintain full structural integrity for load bearing, and relief areas that provide compound containment. The engagement areas preserve complete thread crests and roots for maximum contact area and strength, while relief areas are strategically positioned in zones where reduced material has minimal impact on overall connection strength.
Solution Approach 2:
The relief areas are positioned in specific locations along the axial length where they provide compound containment without compromising the load-bearing engagement zones. The modified geometry in relief areas (reduced crest or increased root) is localized to prevent compound migration while maintaining sufficient material in critical load transmission regions.
3Quantity of substance
If threadform geometry is modified to create relief areas, then thread compound accommodation improves, but manufacturing complexity increases
Solution Approach 1:
The relief areas are created as discrete segments along the axial length rather than continuous modifications. This segmentation allows standard threading operations to create the basic threadform, followed by simpler secondary operations (such as light turning or milling) to create the relief zones, reducing overall manufacturing complexity compared to completely custom threadform geometry.
Solution Approach 2:
The geometric modifications to create relief areas are localized to specific axial positions and involve relatively simple dimensional changes (reducing crest height or increasing root depth) rather than complex profile modifications. This allows the use of standard threading tools for the majority of the threadform, with only localized adjustments needed in relief areas.
Data Source
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AI summary
A connection includes a first tubular member having a first screw threadform defined by a first plurality of crests, roots, and flanks, where each flank separates each crest from each root. The connection also includes a second tubular member having a second screw threadform defined by a second plurality of crests, roots, and flanks, where each flank separates each crest from each root. The crests and roots are substantially axial to the tubular members and the flanks are substantially radial to the tubular members. The first tubular member and the second tubular member are configured to connect when the first threadform engages with the second threadform. Thread compound relief spaces are formed between the first plurality of crests and the second plurality of roots and between the second plurality of crests and the first plurality of roots when the first and second tubular members connect.