Inspection Gauge for Self-Locking Tubular Threading Verification

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Solution Overview

Problem

Conventional self-locking threadings for hydrocarbon well connections are complex to machine and have uncertainties in the locking point, making them incompatible with abutment surfaces, and require precise positioning for sealing surfaces to ensure tightness, necessitating an inspection method to verify conformity.

Innovation Solution

A self-locking threading assembly with an inspection gauge that adapts to the threading by having threads with specific dimensions and curvature to match the shape of the self-locking threading, allowing for precise locking and verification of the locking position, and a method to mark and measure the locking position to ensure correct alignment and torque application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If self-locking threadings are used to increase make-up torque, then the locking reliability is improved, but the manufacturing complexity increases and the locking point becomes uncertain

Engineering Contradiction:
Improvelocking reliabilityVSAvoidthreading manufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The inspection gauge is designed with pre-defined thread dimensions and curvature that match the expected self-locking threading geometry. The gauge allows preliminary verification of the threading conformity before final assembly, ensuring the locking point is correctly positioned and the manufacturing tolerances are met, thereby reducing uncertainty in the locking point while maintaining the complex self-locking design

Inventive Principle:
Principle #10Preliminary action

2Strength

If self-locking threadings are used to achieve high make-up torque, then the connection strength is improved, but the compatibility with abutment surfaces deteriorates due to random locking points

Engineering Contradiction:
Improveconnection strengthVSAvoidcompatibility with abutment surfaces
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The inspection gauge provides feedback on the threading conformity and locking point position. By verifying that the self-locking threading meets the specified tolerances and that the locking point is correctly positioned relative to the abutment surfaces, the system ensures compatibility between the self-locking mechanism and the abutment surfaces, preventing random locking points from compromising the connection

Inventive Principle:
Principle #23Feedback

3Reliability

If precise positioning is used for sealing surfaces to ensure tightness, then the sealing reliability is improved, but the inspection complexity increases

Engineering Contradiction:
Improvesealing reliabilityVSAvoidinspection complexity
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The inspection gauge acts as an intermediary tool that simplifies the verification of precise positioning. The gauge is designed with features that directly indicate when the sealing surfaces are correctly positioned relative to the self-locking threading. By using the gauge to verify the locking point and its relationship to the sealing surfaces, the complexity of detecting and measuring precise positioning is reduced while maintaining high sealing reliability

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2344836B1Inspection assembly for a self-locking threading of a tubular connection used in the oil industry
Publication Date: 2021.12.15 NIPPON STEEL CORPORATION
  • EP2344836B1 patent drawingFigure 1~2
  • EP2344836B1 patent drawingFigure 3~4
  • EP2344836B1 patent drawingFigure 5~6

AI summary

The invention concerns a method and a gauge for inspecting a self-locking threading provided close to one end of a tubular component used for the exploration or operation of hydrocarbon wells, said threading having a lead with a constant width and thread root widths which increase in the direction of the distal surface of the tubular component, characterized in that the gauge is suitable to be displaced in the self-locking threading to a locking position, said locking position then being marked and compared with a reference locking position.