Pipe Flange Overhang Geometry for Single-Pass MAG Welding

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Solution Overview

Problem

High pressure fluctuations in hydraulic applications lead to material fatigue in welded joints of pipes, necessitating time-consuming and costly TIG welding processes for ensuring joint quality, which is inefficient and costly.

Innovation Solution

A method where an overhang on the pipe or flange part covers the weld joint, allowing for the use of faster and more cost-effective MAG welding processes, with the overhang serving as a centering aid and additional welding filler material, enabling a single pass weld and reducing processing time by a factor of 10 compared to TIG welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If TIG welding process is used to ensure joint quality, then welding quality is improved, but production time and cost increase significantly

Engineering Contradiction:

Improvewelding joint qualityVSAvoidproduction speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The pipe end is prepared with a specific geometric shape (beveled edge with overhang) before welding. This preliminary shaping creates a V-shaped groove that enables single-pass welding while maintaining joint quality, eliminating the need for multiple welding layers required by conventional TIG welding

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the geometric parameters of the pipe end (creating a beveled edge with specific overhang dimension), which transforms the welding process from multi-layer TIG welding to single-pass MAG welding, thereby improving both productivity and maintaining reliability

Inventive Principle:

Principle #35Parameter changes

2Reliability

If multiple weld layers are applied to ensure joint quality, then welding reliability is improved, but manufacturing time and complexity increase

Engineering Contradiction:

Improvewelded joint strengthVSAvoidwelding process time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The pipe end is pre-shaped with a beveled edge and overhang structure that creates a V-shaped groove. This preliminary action prepares the joint geometry to accept weld metal in a single pass, eliminating the need for multiple welding layers while ensuring complete penetration and joint strength

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The welding process is segmented into a single continuous pass rather than multiple layers. The V-shaped groove geometry allows the weld metal to be deposited in one continuous operation, reducing both time and process complexity while maintaining joint integrity

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If conventional welding without overhang is used, then manufacturing simplicity is maintained, but weld metal penetration into pipe interior occurs

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidweld metal penetration

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The overhang acts as an intermediary element that physically blocks weld metal from penetrating into the pipe interior. This simple geometric feature serves as a natural barrier, preventing contamination while maintaining the simplicity of the manufacturing process

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The overhang, which could be seen as an additional manufacturing step, actually simplifies the overall process by enabling single-pass welding and preventing weld metal penetration, thereby converting a potential complexity into a beneficial feature

Inventive Principle:

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

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 method significantly reduces production costs and time by enabling faster MAG welding of pipes with improved joint quality and precision, preventing weld metal penetration and ensuring accurate positioning.

Implementation Method 1

the overhang thus forms a kind of cover for the weld joint between the pipe and the flange part, i.e. the connection seam formed is covered in the direction of the pipe interior. This can prevent weld metal from penetrating the inside of the pipe via the weld joint during the welding process

Methodology Applied

Scientific EffectPhysical barrier effect:

Implementation Method 2

the tube and flange part can now be joined by means of MAG welding processes (metal active gas welding)

Methodology Applied

Scientific EffectArc welding:

Implementation Method 3

the overhang can serve as an additional welding filler material. As a result, welding filler material is not only introduced into the weld joint from above, but the excess is also heated and fused with the opposite part

Methodology Applied

Scientific EffectThermal heating and fusion:

Data Source

PatentEP3730826B1Method for producing a pipe with connecting flange

Publication Date: 2022.03.23 LIEBHERR FRANCE

Figure 1~2

AI summary

The invention relates to a method for manufacturing a pipe with a connecting flange, wherein the flange part is welded to an end face of the pipe and at least one projection of the pipe or the flange part is provided in the area of the flange connection, which, when the pipe and the flange part are brought together, rests against the inner wall of the other part in order to cover the weld joint formed to the inside of the pipe, and finally the pipe and the flange part are welded together.