Oil Well Pipe Screw Joint With Minimum Thread Length
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Solution Overview
Problem
The existing screw joints for oil well pipes face challenges in optimizing screw length to balance productivity and shear fracture strength, leading to increased processing and construction times due to excessive screw lengths required for safety.
Innovation Solution
A screw joint design is implemented with a minimum necessary screw length defined by the expression L min = t × D − t / α t × D t / √ 3 × joint efficiency, ensuring the screw length is optimized to prevent shear fracture while maintaining sufficient strength, thereby reducing processing and construction times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the screw length is increased to ensure sufficient strength and prevent shear fracture, then the joint strength is improved, but the processing time and construction time are increased
Solution Approach 1:
The patent applies parameter changes by optimizing the screw length to a specific minimum value defined by the expression Lmin = t×D−t/αt×Dt/√3×joint efficiency. This mathematical formulation transforms the screw length from an arbitrary or excessively long dimension to a precisely calculated optimal value that satisfies both strength requirements and time efficiency, directly resolving the contradiction between joint strength and processing/construction time.
2Productivity
If the screw length is optimized to reduce processing and construction times, then productivity is improved, but the shear fracture strength may be compromised
Solution Approach 1:
The patent uses parameter changes by establishing a minimum screw length threshold through the mathematical expression Lmin = t×D−t/αt×Dt/√3×joint efficiency. This parameter optimization ensures that the screw length is not arbitrarily reduced but is precisely calculated to maintain sufficient shear fracture strength while maximizing productivity, thus resolving the contradiction between productivity and strength.
Solution Approach 2:
The patent replaces empirical or overly conservative mechanical design approaches with a mathematically rigorous formulation. By substituting the traditional trial-and-error or excessive-length methodology with the precise expression involving joint efficiency, shear stress, and geometric parameters, the invention achieves both strength assurance and productivity improvement simultaneously.
Data Source
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AI summary
Provided is a screw joint for an oil well pipe in which an efficient screw length of a joint portion is achieved, and a processing time and a construction time are reduced. The present invention provides a screw joint for an oil well pipe of an integral type, including a pin that is provided with a male screw portion which is a male taper screw, at one end of a steel pipe; and a box that is provided with a female screw portion which is a female taper screw fitted to the male screw portion, at one end of the steel pipe, in which a structure, in which the pin and the box are in metal contact with each other to seal a fluid, is provided at least at one place of a seal portion on an outer peripheral surface side of a pipe end side of the pin and a seal portion on an inner peripheral surface side of a pipe end side of the box, in which a minimum value Lmin (mm) of a screw length L (mm) in screw rows of the male taper screw and the female taper screw is defined by expression (1), and in which the screw length L (mm) in the screw rows satisfies expression (2). Lmin=t×D−t/αt×Dt/√3×jointefficiency Lmin×1.0≤L≤Lmin×2.5