Threaded Connection Perturbed Flanks Seal
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Solution Overview
Problem
Existing thread connections for tubulars, particularly free-running threads, fail to form effective thread seals due to large clearance gaps between pin and box threads, leading to difficulties in sealing high-pressure differentials and increased stress during make-up, while wedge threads face challenges in sealing gases and have indeterminate make-up issues.
Innovation Solution
Introducing perturbations on the thread crests, flanks, and roots of both pin and box members to reduce clearance gaps and increase contact pressure, allowing for a selected thread seal formation by varying thread leads and heights, which enhances sealing capabilities and reduces stress on the connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If free-running threads are used with broad crests and roots, then ease of manufacture is improved, but sealing capability deteriorates due to large clearance gaps
Solution Approach 1:
The patent applies local quality by introducing perturbations only at specific locations on the thread flanks and crests, rather than modifying the entire thread geometry. These localized perturbations create targeted reduced clearance gaps at critical sealing positions while preserving the overall broad crest and root geometry for ease of manufacture. The perturbations are positioned to specifically address sealing gaps without compromising the general thread form.
Solution Approach 2:
The patent employs parameter changes by modifying the thread geometry through introduced perturbations that alter the clearance gap dimensions at specific locations. The perturbations change the local dimensional parameters of the thread flanks and crests, creating variable clearance gaps along the thread length. This allows the majority of the thread to maintain manufacturing-friendly broad dimensions while specific sections have reduced gaps for sealing.
2Reliability
If wedge threads are used to form thread seals, then sealing capability is improved, but make-up determinacy deteriorates due to indeterminate make-up issues
Solution Approach 1:
The patent applies local quality by concentrating the sealing function in specific localized perturbations rather than relying on the entire wedge thread geometry. The perturbations are positioned at specific locations to create localized reduced clearance gaps that form the thread seal, while the rest of the thread maintains a more deterministic geometry. This localization allows the seal to form at predetermined positions without requiring indeterminate make-up conditions.
Solution Approach 2:
The patent applies segmentation by dividing the thread seal formation into discrete localized perturbations rather than a continuous wedge geometry. The perturbations are segmented along the thread length, with each perturbation creating a localized sealing zone. This segmentation allows the thread to have deterministic overall geometry while creating localized sealing regions that do not require indeterminate make-up conditions.
3Reliability
If perturbations are introduced to reduce clearance gaps, then sealing capability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by introducing perturbations only at specific critical locations on the thread rather than modifying the entire thread geometry. This localized approach creates the necessary reduced clearance gaps for sealing while minimizing the overall geometric complexity. The perturbations are confined to specific segments of the thread, leaving the majority of the thread geometry simple and straightforward to manufacture.
Solution Approach 2:
The patent applies partial action by introducing perturbations at only the critical sealing locations rather than modifying the entire thread length. This partial modification is sufficient to achieve the sealing function without the excessive complexity that would result from uniform perturbations along the entire thread. The perturbations are applied selectively where needed for sealing, maintaining simplicity elsewhere.
Data Source
AI summary
A threaded connection including a pin member and a box member, and methods for manufacturing and forming said threaded connection. The pin member has a pin thread with a pin thread crest, a pin thread root, a pin load flank, and a pin stab flank. The box member has a box thread with a box thread crest, a box thread root, a box load flank, and a box stab flank. At least one of the pin thread crest, the pin load flank, the pin stab flank, the box thread crest, the box load flank, and the box stab flank has at least one perturbation formed thereon. Upon a selected make-up of the pin member with the box member, a reduced clearance gap exists between the pin thread and the box thread at the at least one perturbation.