Pressure Test Plug With Annular Seal for Threaded Tubular Ends

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Solution Overview

Problem

Existing pressure test solutions for tubular components with superior threaded joints are inadequate, particularly for male threaded ends lacking axial abutment or featuring a path of escape, leading to significant leaks and compromising the quality of the upper threaded end during testing.

Innovation Solution

A pressure test assembly comprising a plug with a male thread, an inner annular groove, and a sealing ring, where the groove is positioned between the male thread and the free end, with a tapered bottom matching the inclination of the frustoconical sealing surface, ensuring homogeneous compression and preventing leaks, and a compatible thread that avoids radial interference to preserve the thread integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional plug is used for pressure testing male threaded ends, then the testing can be performed, but significant leaks occur and the thread integrity is compromised

Engineering Contradiction:
Improvesealing performanceVSAvoidthread damage and leaks
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A sealing ring is introduced as an intermediary element between the plug and the male threaded end. The sealing ring deforms under compression to fill gaps and create a reliable seal, preventing leaks without requiring direct metal-to-metal contact that could damage the threads. The sealing ring acts as a mediator that accommodates dimensional variations and surface imperfections.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The plug design incorporates a tapered portion with a specific inclination that matches the male threaded end geometry. By adjusting the dimensional parameters of the tapered portion and the compression force applied to the sealing ring, the seal quality is optimized. The parameter changes in the plug structure enable adaptation to different thread sizes and specifications.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the plug is designed to tightly seal the male threaded end, then leaks are prevented, but the plug becomes difficult to screw on and off

Engineering Contradiction:
Improvesealing performanceVSAvoidscrewing ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The plug features a tapered portion with a specific inclination that locally matches the male threaded end geometry. This localized geometric matching creates a self-aligning effect that guides the plug onto the thread during assembly, reducing the torque required and making the operation easier. The local quality of the tapered surface provides both sealing and operational benefits.

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If the plug design accommodates male threaded ends with path of escape, then versatility is improved, but sealing reliability deteriorates due to pressure leakage paths

Engineering Contradiction:
Improvecompatibility with different thread typesVSAvoidsealing performance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The plug is designed with a universal sealing mechanism that can accommodate different male threaded end configurations, including those with path of escape features. The sealing ring and tapered portion combination can adapt to various thread geometries and pressure conditions, making the plug versatile for testing different tubular components while maintaining sealing reliability through the flexible sealing ring design.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides a reusable, easy-to-screw cap that effectively prevents leaks during pressure testing, ensuring the integrity of the tubular component and maintaining the quality of the upper threaded end, while allowing for homogeneous compression and axial expansion absorption.

Implementation Method 1

a seal ring retained in said groove such that the seal ring is radially compressed between an outer periphery of the male threaded element and a bottom of said inner annular groove

Methodology Applied
Scientific EffectRadial compression: Compression

Implementation Method 2

a tapered bottom matching the inclination of the frustoconical sealing surface, ensuring homogeneous compression

Methodology Applied
Scientific EffectHomogeneous compression: Compression

Implementation Method 3

allowing for homogeneous compression and axial expansion absorption

Methodology Applied
Scientific EffectAxial expansion: Thermal Expansion

Data Source

PatentEP3347689B1Pressure test assembly comprising a plug and an improved tubular threaded component
Publication Date: 2022.07.13 VALLOUREC MANNESMANN OIL & GAS FRANCE
  • EP3347689B1 patent drawingFigure 1~5
  • EP3347689B1 patent drawingFigure 2~6
  • EP3347689B1 patent drawingFigure 3~4

AI summary

Plug (10) for a pressure test suitable for a tubular component, the tubular component comprising a male threaded element (1) at a free end (4), such that the male threaded element comprises a male thread (2) and a sealing surface (6), the plug comprising a thread (16) compatible with the male thread, an inner annular groove (19) and a sealing ring (20) held in said groove in such a manner that the sealing ring is radially compressed between an outer periphery of the male threaded element and a bottom (23) of said inner annular groove.