Multi-thread Gauging for Oilfield Tubular Connections

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Solution Overview

Problem

Conventional gauging techniques are unable to reliably test multi-start threads in oilfield tubular connections, as double-start gauges may indicate acceptable measurements while individual threads remain out of tolerance.

Innovation Solution

The method involves successively and simultaneously using single-thread and multi-thread ring and plug gauges to gauge each external and internal starting thread on a pin and box member, respectively, ensuring accurate measurement of stand-offs and stand-ins within acceptable limits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a double-start gauge is used to gauge multi-start threads, then the gauging process is simplified and time is reduced, but the measurement reliability deteriorates as individual threads may be out of tolerance while the gauge still indicates acceptable measurements

Engineering Contradiction:
Improvegauging speedVSAvoidmeasurement reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The gauging process is segmented into multiple independent measurements: one measurement using a multi-thread ring gauge for overall thread form verification, and additional measurements using single-thread ring gauges for each individual thread start. This segmentation allows the system to maintain both efficiency (through the multi-thread gauge) and reliability (through individual thread verification) by breaking down the complex gauging task into manageable components that address different aspects of thread quality.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If conventional gauging techniques are used for multi-start threads, then the gauging process is simple, but the measurement precision deteriorates as it cannot reliably detect individual thread tolerances

Engineering Contradiction:
Improvegauging process complexityVSAvoidthread tolerance detection precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

Single-thread ring gauges are introduced as intermediary measurement tools that target specific individual thread starts. These single-thread gauges act as mediators between the complex multi-start thread structure and the measurement system, allowing precise verification of each individual thread's tolerance. The multi-thread gauge provides the primary measurement framework, while the single-thread gauges provide the necessary detailed verification that conventional techniques cannot achieve.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP1837620B1Multi-thread gauging method
Publication Date: 2009.04.29 GRANT PRIDECO LP
  • EP1837620B1 patent drawingFigure 1~2
  • EP1837620B1 patent drawingFigure 3~4

AI summary

A system and method are provided for gauging multi-start threads on an oilfield tubular connection include a pin member 12 and a box member 42. One or more external starting threads are successively gauged with a single thread ring gauge 22, and the same threads are simultaneously gauged with a multi-thread ring gauge 32. Each of two or more internal starting threads are successively gauged with a single thread plug gauge 52, and the same threads are simultaneously gauged with a multi-thread plug gauge 62.