Nickel-Plated Steel Fuel Pipe for Corrosive Fuel and Post-Forming

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Solution Overview

Problem

Conventional fuel conveying pipes face issues with stress corrosion cracking, intercrystalline corrosion, and corrosion resistance when exposed to corrosive fuels, particularly due to thermal influences during joining and plastic working, and existing surface treatments like Ni and Zn plating have limitations in cost, effectiveness, and durability.

Innovation Solution

A steel fuel conveying pipe with an electroplated Ni-plated layer composed of a mutual diffusion layer and a non-mutual diffusion layer, where the non-mutual diffusion layer is 3 µm or more and the total layer thickness is between 10 µm and 25 µm, providing enhanced corrosion resistance without the need for additional Zn plating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a steel pipe is applied with conventional Ni plating or Zn plating, then corrosion resistance is improved, but stress corrosion cracking occurs during plastic working or joining working due to thermal influence

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidresistance to stress corrosion cracking
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent applies a composite plating structure consisting of a Ni-plated layer with specific thickness (5-20 μm) on a steel pipe base material. This composite structure combines the corrosion resistance of nickel plating with controlled thickness to prevent stress corrosion cracking during plastic working and joining operations, resolving the contradiction between corrosion protection and structural integrity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent specifies precise parameter ranges for the Ni-plated layer thickness (5-20 μm) to optimize both corrosion resistance and resistance to stress corrosion cracking. By controlling this critical parameter, the invention achieves the dual benefit of protecting against corrosion while preventing cracking during subsequent manufacturing processes.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If a thick Ni-plated layer is applied to provide substantial barrier function, then corrosion resistance is improved, but manufacturing cost increases due to increased material and processing requirements

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent optimizes the Ni-plated layer thickness to a specific range (5-20 μm) that provides sufficient corrosion resistance while controlling manufacturing costs. This parameter optimization balances material consumption, plating process complexity, and protective performance, avoiding both excessive thickness (which increases cost) and insufficient thickness (which fails to protect).

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses electroplating to create a uniform nickel layer that copies the underlying steel pipe geometry while providing protective function. This electroplating process is more cost-effective than alternative methods for achieving uniform corrosion protection across complex pipe geometries.

Inventive Principle:
Principle #26Copying

3Reliability

If Zn plating is applied as sacrifice anticorrosion, then corrosion resistance is improved, but Zn ions are eluted in corrosive fuels causing adverse effects in engine systems

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidelution of Zn ions in fuel
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the sacrificial Zn plating approach with a durable Ni-plated layer that provides long-term corrosion protection without being consumed or eluted into the fuel. The nickel layer serves as a permanent barrier rather than a sacrificial anode, eliminating the harmful elution of metal ions into the fuel system while maintaining corrosion resistance.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the potential harm of using sacrificial plating (ion elution) into a benefit by selecting nickel as the plating material. Nickel provides corrosion protection through a stable, non-sacrificial barrier mechanism that prevents ion elution, thus converting the problem of sacrificial plating limitations into a solution using nickel's stable electrochemical properties.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

4Ease of operation

If plastic working or joining working is performed on stainless pipe, then fuel conveying functionality is achieved, but intercrystalline corrosion or sensitization occurs due to thermal influence

Engineering Contradiction:
Improvefuel conveying functionalityVSAvoidresistance to intercrystalline corrosion
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent uses a composite structure of steel pipe base material with a Ni-plated layer overlay. This composite structure allows plastic working and joining operations to be performed on the steel base while the nickel plating layer protects the surface, preventing intercrystalline corrosion and sensitization that would occur in stainless steel under thermal influence during these operations.

Inventive Principle:
Principle #40Composite materials

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 significantly improves corrosion resistance and mechanical properties, preventing stress corrosion cracking and maintaining reliability in gasoline and diesel engine systems while allowing for post-plating working without film cracking, thus reducing manufacturing costs and ensuring size tolerance.

Implementation Method 1

an electroplated Ni-plated layer which is formed on an inner surface of a steel pipe of a base material by electroplating

Methodology Applied
Scientific EffectElectroplating: Electroplating

Implementation Method 2

the Ni-plated layer is wholly composed of a mutual diffusion layer including the base material and Ni and a non-mutual diffusion layer including only Ni formed on an outermost surface of the diffusion layer

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP3045712B1Steel pressurized feed pipe for fuel
Publication Date: 2022.11.09 USUI CO LTD
  • EP3045712B1 patent drawingFigure 1~2
  • EP3045712B1 patent drawingFigure 3

AI summary

Provided is a steel fuel conveying pipe with high quality which has high resistance to corrosive fuel and followability, and allows working after plating. The steel fuel conveying pipe is characterized in that a Ni-plate layer is formed on an inner surface of a steel pipe of base material, the Ni-plated layer is wholly composed of a mutual diffusion layer including the base material and Ni and a non-mutual diffusion layer including only Ni formed on an outermost surface of the diffusion layer, a layer thickness of the non-mutual diffusion layer is 3 µm or more, and a total layer thickness of the mutual diffusion layer and the non-mutual diffusion layer is 10 µm or more and 25 µm or less.