Tapered Thread Oil Well Pipe Coupling Structure
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Solution Overview
Problem
Existing oil well pipe coupling methods face challenges such as prolonged welding times, reduced workability, limited axial strength, increased hole sizes for deeper wells, and leakage issues due to deformation or cracking under high temperatures or loads.
Innovation Solution
A coupling structure featuring oil well pipes with external and internal thread portions, where the external thread has a first straight portion and a second tapered portion, and the internal thread has a corresponding configuration, allowing for enhanced axial strength and sealing performance without increasing pipe sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If welding is used to couple oil well pipes, then the connection strength is improved, but the working time increases and workability deteriorates
Solution Approach 1:
The patent replaces the welding process (thermal/chemical system) with a mechanical threading system. The external thread portion on one pipe engages with the internal thread portion on another pipe through screwing, achieving strong mechanical coupling without welding. This substitution eliminates the time-consuming welding process while maintaining connection strength through precise thread geometry and material properties.
2Ease of manufacture
If straight threads are used for pipe connection, then the manufacturing is simpler, but the axial strength is limited to less than 50% of total cross-sectional strength
Solution Approach 1:
The patent transforms the thread geometry from straight (cylindrical) to tapered (conical), changing the dimensional parameters along the thread length. The external thread portion has a larger diameter at the base that tapers toward the tip, while the internal thread portion has a corresponding inverse taper. This parameter change enables the threads to engage over a longer effective length with progressive load distribution, achieving axial strength exceeding 50% of total cross-sectional strength while remaining manufacturable through standard threading processes.
3Strength
If tapered threads are used to improve axial strength, then the strength increases to approximately 70% of total cross-sectional strength, but the connection still lacks sufficient strength under high temperatures or heavy loads
Solution Approach 1:
The patent divides the threading system into two distinct segments: an external thread portion and an internal thread portion with complementary but different geometries. The external thread has a taper angle that is greater than the internal thread's taper angle, creating a interference fit when engaged. This segmentation allows each thread portion to be optimized for its specific function while working together to provide both the 70%+ axial strength and the sealing reliability needed for high-temperature and heavy-load conditions.
4Strength
If larger hole sizes are used for deeper well installations, then the pipe strength and load-bearing capacity are improved, but the operational costs increase
Solution Approach 1:
The patent creates a composite threading structure where the external thread and internal thread portions work together as an integrated system. The combination of tapered geometries, interference fit, and extended engagement length produces a composite effect that maximizes load-bearing capacity within the existing pipe dimensions. This eliminates the need for larger hole sizes during installation while maintaining the required strength for deeper well applications, thereby reducing operational costs.
Data Source
AI summary
Provided is means for connecting oil well pipes together with a compact/simple structure and the strength that significantly exceeds the limits of prior art even without the flange, etc. An oil well pipe coupling structure includes a first oil well pipe and a second oil well pipe, the external thread portion has a first external thread portion, a substantially tapered second external thread portion, and a third external thread, the internal thread portion has a first internal thread portion, a substantially tapered second internal thread portion, and a third internal thread portion the first external thread portion is screwed to the first internal thread portion, the second external thread portion is screwed to the second internal thread portion, the third external thread portion is screwed to the third internal thread portion, and the first oil well pipe and the second oil well pipe are coupled