Steel Pipe AC Resistance Measurement Using Induction and Yoke

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Solution Overview

Problem

Existing methods for determining the linear electrical resistance in AC mode of steel pipelines are time-consuming, require grinding, and involve bulky equipment, making them inefficient for ensuring homogeneous heating power throughout the pipeline.

Innovation Solution

A method using an induction coil centered on the pipeline's longitudinal axis, housed in a ferromagnetic yoke, to generate a magnetic field and measure active power dissipation, allowing for rapid and non-invasive determination of linear AC electrical resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct power supply method is used to measure linear AC electrical resistance, then measurement can be performed, but measurement time is long (about 15 min for a 12 m pipeline section)

Engineering Contradiction:

Improvelinear AC electrical resistance measurementVSAvoidmeasurement cycle time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the direct electrical contact measurement system with an electromagnetic induction system. The induction coil generates a magnetic field that induces currents in the pipeline, allowing resistance measurement without direct electrical contact. This substitution of measurement mechanism enables rapid scanning of pipeline sections while maintaining measurement accuracy, reducing measurement time from 15 minutes to a few seconds per section.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If direct power supply method is used, then linear AC electrical resistance can be determined, but grinding of pipeline section is required at connection points

Engineering Contradiction:

Improvelinear AC electrical resistance measurementVSAvoidpipeline section preparation

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The invention replaces direct electrical contact requiring mechanical grinding with electromagnetic induction. The induction coil generates a magnetic field that penetrates the pipeline wall and induces currents without needing electrical contact. This eliminates the grinding requirement entirely, making the measurement process non-invasive and suitable for finished pipelines.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnetic field as an intermediary between the measurement system and the pipeline. Instead of direct electrical contact requiring ground connection points, the magnetic field serves as the mediator that transfers energy through the pipeline wall, inducing measurement currents without mechanical preparation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If direct power supply equipment is used for measurement, then resistance determination is possible, but equipment is quite bulky

Engineering Contradiction:

Improvelinear AC electrical resistance measurementVSAvoidmeasurement equipment size

Core Design Contradiction:

Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent replaces bulky direct power supply equipment with a compact electromagnetic induction system. The induction coil and control electronics can be housed in a portable unit that generates the necessary magnetic field without requiring large power supply apparatus. This substitution dramatically reduces equipment size and portability requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method significantly reduces measurement time and eliminates the need for grinding, while providing precise and efficient determination of AC electrical resistance on both inner and outer pipeline faces.

Implementation Method 1

generating in a pipeline portion to be measured an induced current resulting from the production of a magnetic field at a predefined frequency by means of an induction coil

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the induction coil being housed in a yoke made of ferromagnetic material in order to confine the magnetic field to a predefined surface of the pipeline portion

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Implementation Method 3

measuring the active power dissipated by the pipeline portion subjected to the magnetic field

Methodology Applied

Scientific EffectJoule effect: Joule Heating

Data Source

PatentUS12385864B2Method for determining the linear AC electrical resistance of a steel pipe and device for implementing such a method

Publication Date: 2025.08.12 SAIPEM SA

AI summary

A method for determining the linear electrical resistance in AC mode of a steel pipeline, including the steps of generating in a portion of the pipeline an induced current by means of an induction coil centered on a longitudinal axis of the pipeline and traversed by an AC current. The coil is housed in a yoke made of ferromagnetic material in order to confine the magnetic field to a predefined surface of the pipeline portion, measuring the active power dissipated by the pipeline portion subjected to the magnetic field, measuring the amplitude of the produced magnetic field, and determining the linear electrical resistance in AC mode of the pipeline portion from the measurements of the dissipated active power and the amplitude of the induced magnetic field. A device is provided for implementing such a method.