Pin End Axial Extension for Accurate Threaded Tubular Gauging
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Solution Overview
Problem
The existing threaded tubulars in the oil and gas industry face challenges in accurately measuring the diameter of pin ends due to the presence of external thread profiles and irregular chamfers, which obstruct precise diameter measurements during the manufacturing process.
Innovation Solution
The design incorporates an axial extension on the pin end that terminates the external thread profile, providing a gauge surface unobstructed by threads, allowing for accurate diameter measurements and improving quality control, while also enhancing torque performance and reducing the risk of axial collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threading extends along the entire pin end, then the structural integrity and torque performance are improved, but accurate diameter measurement becomes impossible
Solution Approach 1:
The pin end is segmented into two functional zones: a threaded portion for structural connection and torque transmission, and an unthreaded axial extension for measurement purposes. This segmentation allows each zone to fulfill its specific function without interfering with the other, resolving the contradiction between maintaining threaded integrity and enabling accurate diameter measurement.
Solution Approach 2:
The measurement function is extracted from the threaded portion by creating a separate unthreaded axial extension. This extracted measurement zone provides a clear, unobstructed surface for diameter measurement while the threaded portion maintains its structural and torque-transmission functions, eliminating the measurement obstacle caused by threading.
2Strength
If threading extends along the entire pin end, then the connection strength is improved, but manufacturing quality control becomes difficult
Solution Approach 1:
The pin end structure is divided into threaded and unthreaded sections, with the unthreaded axial extension serving as a dedicated quality control reference. This segmentation provides a clear manufacturing benchmark for verifying outer diameter accuracy and thread engagement depth, enabling effective quality control without compromising connection strength in the threaded portion.
3Force
If the external thread profile extends to the pin end face, then the torque performance is maximized, but the risk of axial collapse increases
Solution Approach 1:
The external thread profile is extracted from the extreme axial end of the pin end, creating an unthreaded axial extension. This extraction removes the stress concentration and structural weakness at the pin end face, reducing the risk of axial collapse, while the threaded portion maintains sufficient length to provide adequate torque performance for connection.
Data Source
AI summary
A tubular member includes a pin end terminating in a pin end face, an external thread profile defined on an outer circumference of the pin end and terminating at a thread termination location axially offset from the pin end face, and an axial extension provided on the pin end and extending axially from the thread termination location to the pin end face, the axial extension defining a gauge surface for obtaining diameter measurements of the pin end. An angle of the gauge surface aligns with an angle of a root plane provided by the external thread profile.