Stainless-Steel Derouging Composition for Magnetite Removal

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Solution Overview

Problem

Current methods for removing Type III Rouge (magnetite corrosion) from stainless-steel surfaces are inefficient, often requiring high temperatures, long treatment times, and use of hazardous acids, posing safety risks and substrate damage.

Innovation Solution

A liquid concentrate composition comprising oxalic acid, phosphonic acid, and amines, optionally with hydrotrope or wetting surfactants, effectively solubilizes and removes Type I and Type III Rouge by enhancing magnetite solubility without using strong acids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If stronger acids such as hydrochloric acid or hydrofluoric acid are used to remove corrosion material, then better efficacy in removing corrosion material is achieved, but further damage to stainless-steel occurs and significant safety and handling concerns arise

Engineering Contradiction:
Improvecorrosion removal efficacyVSAvoidstainless-steel damage and safety risks
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters by using oxalic acid (a weaker acid) combined with phosphonic acid and amine additives to achieve effective magnetite removal without the damaging effects of strong acids. This parameter change allows achieving good corrosion removal efficacy while avoiding stainless-steel damage and safety hazards associated with hydrochloric or hydrofluoric acid

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite chemical system consisting of oxalic acid, phosphonic acid, and amine additives working together synergistically. This composite approach enables effective magnetite corrosion removal while maintaining stainless-steel substrate integrity and eliminating the need for hazardous strong acids

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If weaker acids such as acetic acid or citric acid are used, then safety is improved, but poor solubilization of magnetite occurs and corrosion removal efficacy is insufficient

Engineering Contradiction:
Improvesafety and substrate damageVSAvoidcorrosion removal efficacy
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent combines oxalic acid with phosphonic acid and amine additives to create a composite formulation that overcomes the limitations of weaker acids alone. This composite system achieves both safety and effective magnetite solubilization, delivering superior corrosion removal efficacy compared to using weak acids by themselves

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The amine additives act as intermediaries that enhance the solubilization capability of the acid system toward magnetite. These intermediaries facilitate the interaction between the acid components and magnetite corrosion, enabling effective removal while maintaining the safety benefits of weaker acids

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If conventional derouging processes use high temperature and long treatment time, then corrosion removal capability is improved, but energy consumption increases and process complexity increases

Engineering Contradiction:
Improvecorrosion removal capabilityVSAvoidtemperature and treatment time requirements
Core Design Contradiction:
ProductivityVSUse of energy by stationary object

Solution Approach 1:

The patent changes the operational parameters by enabling effective corrosion removal at lower temperatures and shorter treatment times compared to conventional processes. The optimized formulation of oxalic acid, phosphonic acid, and amine additives achieves superior magnetite removal capability without requiring high temperature or extended treatment time, thereby reducing energy consumption and simplifying the derouging process

Inventive Principle:
Principle #35Parameter changes

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 composition achieves up to a 3-fold improvement in magnetite solubility, achieving 90-95% Type I Rouge removal and 15,000 ppm magnetite solubility, while being safe and substrate-friendly.

Implementation Method 1

The composition achieves up to a 3-fold improvement in magnetite solubility, achieving 15,000 ppm magnetite solubility

Methodology Applied
Scientific EffectSolubilization: Solvation

Implementation Method 2

The liquid composition comprises oxalic acid, or oxalic acid dihydrate, phosphonic acids, various amines... effectively solubilizes and removes Type I and Type III Rouge

Methodology Applied
Scientific EffectChemical dissolution:

Implementation Method 3

The use of an amine has generally been found to provide synergistic results in removal of Rouge III Type corrosion from various stainless-steel items

Methodology Applied
Scientific EffectSynergistic chemical interaction:

Implementation Method 4

various surfactants and water... surfactants that is capable of wetting, dispersing, or emulsifying said concentrate composition

Methodology Applied
Scientific EffectWetting: Wetting

Implementation Method 5

surfactants that is capable of wetting, dispersing, or emulsifying said concentrate composition

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Data Source

PatentEP3938483B1Liquid product for stainless-steel corrosion remediation
Publication Date: 2025.12.03 AMERICAN STERILIZER CO
  • EP3938483B1 patent drawingFigure 1
  • EP3938483B1 patent drawingFigure 2
  • EP3938483B1 patent drawingFigure 3

AI summary

A concentrate aqueous composition for removing Type I and Type III rouge from various stainless-steel items. The liquid composition comprises oxalic acid, a phosphonic acid, and various amines. The use of an amine has been found to provide synergistic results in removal of the noted types of corrosion from various stainless-steel items that include medical instruments, machines, equipment, pipes, tools, mixing and storage vessels, and the like.