Intermediate-Shoulder Threaded Connection for Thin-Wall Pipe Sealing
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Solution Overview
Problem
Existing threaded tubular connections for hydrocarbon transport face challenges in maintaining mechanical strength and fluid tightness under varying stresses, requiring thicker pipes to ensure geometric and mechanical integrity while adhering to API standards.
Innovation Solution
A threaded tubular connection design featuring a female portion with an inner and outer threaded portion offset radially, combined with a male portion having a domed and conical section for a fluid-tight seal, allowing for reduced pipe thickness without compromising mechanical strength or sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pipe thickness is increased to ensure mechanical strength and geometric integrity, then structural strength is improved, but device complexity and material usage increase
Solution Approach 1:
The patent applies local quality by creating an intermediate shoulder with non-uniform wall thickness distribution. The shoulder portion has increased thickness specifically where needed to handle stress concentrations, while other portions maintain standard thickness. This localized thickening provides enhanced mechanical strength exactly where required without increasing overall pipe thickness throughout the entire structure.
Solution Approach 2:
The pipe end is segmented into distinct functional zones: a first portion with standard thickness, an intermediate shoulder with increased thickness, and a second portion with standard thickness. This segmentation allows each zone to be optimized for its specific function - the shoulder handles stress concentration while the thinner portions reduce overall material usage and complexity.
2Device complexity
If pipe thickness is reduced to minimize material usage, then device complexity is decreased, but mechanical strength and sealing performance deteriorate
Solution Approach 1:
Instead of uniformly reducing pipe thickness, the invention applies local quality by maintaining standard thickness in non-critical areas while selectively increasing thickness only at the intermediate shoulder where stress concentrations occur. This ensures mechanical strength is preserved at critical locations while minimizing overall material usage and device complexity.
3Ease of manufacture
If uniform wall thickness is used throughout the pipe end, then manufacturing is simplified, but stress concentration and plastic deformation increase under cyclic loading
Solution Approach 1:
The intermediate shoulder creates a local quality variation with increased wall thickness at the transition zone. This localized thickening specifically addresses stress concentration areas under cyclic loading, improving resistance to plastic deformation and fatigue failure, while the rest of the pipe maintains standard manufacturing practices.
4Reliability
If standard threaded connection design is used, then compatibility with API standards is maintained, but sealing performance under varying stresses is insufficient
Solution Approach 1:
The threaded connection is segmented into distinct functional zones including an intermediate shoulder portion. This segmentation creates specialized areas for different functions - the shoulder provides stress distribution and sealing support, while threaded portions provide mechanical connection. This structured segmentation improves sealing performance under varying stresses while maintaining organized, manageable complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design achieves a fluid-tight seal with reduced pipe thickness, maintaining mechanical strength and compatibility with API standards, while minimizing plastic deformation and enhancing service load capacity under stress cycles.
Implementation Method 1
The domed portion and the conical section contact to form an internal fluid tight seal once the male portion is connected to the female portion. Such internal fluid tight seal is set up by defining a seal interference, determined radially, prior make up, between respectively the domed portion outer diameter and the conical section inner diameter.
Data Source
Figure 1
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AI summary
A threaded tubular connection (10) comprises a first tubular component (12) and a second tubular component (14). The first tubular component (12) includes a female portion (16) defined on an interior surface of the first tubular component (12). The female portion includes an inner threaded portion (16d) and an outer threaded portion (16b) which are offset radially with respect to a longitudinal axis of the first tubular component by a first shoulder (16c). The second tubular component (14) includes a male portion (18) defined on an exterior surface of the second tubular component (14). The male portion is to be inserted into the female portion, and includes an inner threaded (18b) portion and an outer threaded portion (18d) which are offset radially with respect to a longitudinal axis of the second tubular component by a second shoulder (18c). The second shoulder is to abut the first shoulder once the male portion is connected to the female portion. The threaded tubular connection comprises an inner short length fluid tight seal (50, 52).