Variable-Pitch Tubular Connection for Reliable Seal Positioning
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Solution Overview
Problem
Existing threaded connections for tubular components in hydrocarbon wells face issues with unreliable sealing due to manufacturing tolerances, leading to improper relative positioning of sealing surfaces, which can result in sealing defects or degradation, despite the use of visual markers and buttressing surfaces.
Innovation Solution
A tubular connection system with variable tooth width threads and a reference mark positioned based on actual component characteristics, using equations to correct for manufacturing tolerances, ensuring precise and reliable relative positioning of sealing surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If visual markers and buttressing surfaces are used to ensure proper relative positioning of sealing surfaces, then sealing reliability is improved, but device complexity and radial space requirements increase
Solution Approach 1:
The patent removes the buttressing surfaces from the connection design, extracting the problematic element that caused stress concentration and radial space occupation. Instead of using physical buttressing surfaces to control relative positioning, the invention relies on the variable-width thread geometry itself to achieve proper sealing surface alignment, thereby simplifying the overall device structure while maintaining sealing reliability
Solution Approach 2:
The patent applies local quality through variable-width sealing surfaces where the width varies axially along the sealing surface. This localized variation in geometry allows the sealing surfaces to self-align properly during assembly without requiring additional buttressing structures, achieving both simplified design and reliable sealing through locally optimized geometric properties
2Reliability
If visual markers and buttressing surfaces are used to ensure proper relative positioning of sealing surfaces, then sealing reliability is improved, but manufacturing precision requirements increase due to tolerance accumulation
Solution Approach 1:
The patent changes the geometric parameters of the thread profile by implementing variable tooth width that varies axially. This parameter variation creates a self-aligning mechanism where the geometry itself compensates for manufacturing tolerances, eliminating the need for high-precision positioning that would otherwise be required when using visual markers and buttressing surfaces
Solution Approach 2:
The variable-width thread geometry provides self-service by automatically compensating for manufacturing tolerances during assembly. The non-uniform thread profile ensures proper engagement and alignment of sealing surfaces without requiring external positioning aids or exceeding normal manufacturing precision capabilities, making the system self-correcting regarding tolerance accumulation
3Reliability
If variable-width threads with interference are used to ensure high torque and sealing, then sealing performance is improved, but risk of seizing and damage to sealing surfaces increases
Solution Approach 1:
The patent applies local quality by varying the thread tooth width along the axial direction, creating regions of different interference characteristics. This localized geometric variation ensures adequate interference for sealing in critical areas while maintaining lower interference in other regions, preventing excessive stress concentration that could lead to seizing or damage of sealing surfaces
Solution Approach 2:
The patent changes the thread geometry parameters by implementing variable tooth width, which modifies the interference distribution along the thread engagement length. This parameter variation allows optimization of the balance between sufficient interference for sealing and limited interference to prevent seizing, resolving the contradiction between sealing performance and damage risk
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a tubular connection (1) comprising a first tubular component (2) and a second tubular component (3), each tubular component (2, 3) comprising a thread (8) and a sealing surface (9, 7, 13, 15), the threads (8, 14) having a variable thread pitch, the threads (8, 14) being intermeshed when the tubular connection (1) is in a mounted state, the sealing surfaces (7, 9, 13, 15) being in sealed contact when the tubular connection (1) is in the mounted state, the tubular connection (1) comprising a reference mark (26), the reference mark having an optimal relative position between the tubular components (2, 3), characterised in that the optimal relative position corresponds to a nominal optimal relative position to which a correction is applied, the correction being dependent on the characteristics of the one from among the first tubular component (2) and the second tubular component (3) on which the reference mark is arranged and on a target torque of the tubular connection (1).