Clad Steel Pipe Welding With Pre-Bent Edges to Preserve Corrosion Resistance

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Solution Overview

Problem

Conventional high-frequency longitudinal welding of clad steel pipes requires subsequent non-continuous processes for repair welding due to thinning of the clad layer at the weld, compromising corrosion resistance and efficiency.

Innovation Solution

The method involves bending both sides of the clad steel plate towards the base layer before forming, allowing for continuous high-efficiency welding without additional repair processes, ensuring the integrity of the clad layer and maintaining corrosion resistance by positioning the clad layer on either the inner or outer surface of the pipe blank.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high-frequency longitudinal welding is used to join the edges of the clad steel plate, then welding efficiency and continuity are improved, but the clad layer metal is extruded and thinned at the weld, reducing corrosion resistance

Engineering Contradiction:
Improvewelding efficiencyVSAvoidcorrosion resistance at weld
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The edges of the clad steel plate are bent towards the base layer side before welding. This preliminary action creates a geometric configuration where the opening faces are clad layer, positioning the clad layer to be extruded outward during welding rather than being thinned at the weld interface, thus preserving corrosion resistance while maintaining welding efficiency

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If the clad layer is scraped off after welding to remove burrs, then surface quality is improved, but the clad layer integrity is compromised and corrosion resistance is reduced

Engineering Contradiction:
Improvesurface qualityVSAvoidcorrosion resistance
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

By bending the edges before welding, the clad layer is positioned to form the opening faces of the pipe blank. This preliminary configuration ensures that during welding, the clad layer is extruded outward to form burrs that can be removed without compromising the clad layer at the weld interface, thus allowing deburring while maintaining corrosion resistance

Inventive Principle:
Principle #10Preliminary action

3Reliability

If repair welding is performed after initial welding to restore clad layer integrity, then corrosion resistance is improved, but the continuous production process is interrupted and productivity is reduced

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidproduction continuity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The edges are bent before welding to pre-position the clad layer for optimal extrusion during welding. This preliminary action eliminates the need for subsequent repair welding by ensuring the clad layer integrity is maintained throughout the welding process, thus maintaining both corrosion resistance and production continuity

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The bending configuration enables continuous high-frequency longitudinal welding without interruption for repair processes. The clad layer is positioned to be extruded outward during welding, maintaining integrity throughout the continuous welding process and eliminating the need for non-continuous repair operations

Inventive Principle:
Principle #20Continuity of useful action

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

This approach simplifies the manufacturing process, maintains corrosion resistance at the weld, and enhances mechanical properties by eliminating the need for off-line repair welding, while maintaining the efficiency of the high-frequency longitudinal welding process.

Implementation Method 1

high-frequency resistance welding method

Methodology Applied
Scientific EffectResistive heating: Joule Heating

Implementation Method 2

the base metal at the weld is melted

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

both sides of the clad steel plate are bent towards the base layer side

Methodology Applied
Scientific EffectPlastic deformation: Deformation

Implementation Method 4

the clad layer metal is extruded and becomes a part of the burr

Methodology Applied
Scientific EffectMetal extrusion: Extrusion

Data Source

PatentEP3603880B1Method for manufacturing clad steel pipe
Publication Date: 2024.12.25 BAOSHAN IRON & STEEL CO LTD
  • EP3603880B1 patent drawingFigure 1~3
  • EP3603880B1 patent drawingFigure 4~5
  • EP3603880B1 patent drawingFigure 6~7

AI summary

A method for manufacturing a clad steel pipe is provided, wherein the clad steel pipe is manufactured by using a clad steel plate as a raw material. The clad steel plate comprises a base layer (1) and a clad layer (2) roll-bonded with the base layer (1). The method for manufacturing a clad steel pipe comprises the steps of forming, welding, and deburring; both sides of the clad steel plate are bent towards the base layer (1) side of the clad steel plate, then the forming step is carried out, and after the forming step, the opening faces of the resultant pipe blank are all in a form of the clad layer (2). According to the method for manufacturing a clad steel pipe, a clad steel pipe is manufactured by using a clad steel plate as a raw material. Thus, continuance and high efficiency of a high-frequency longitudinal welding pipe unit is fully utilized, subsequent non-continuous processes are not necessary, and the corrosion resistance at the weld of the clad steel pipe is ensured