Clad Welded Pipe Groove Welding to Limit Weld Width
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing electric-resistance-welded clad steel pipes or tubes face challenges in reducing the width of the weld metal while maintaining the mechanical properties and corrosion resistance, as excessive upset during welding can expose the base metal, degrading the properties and requiring post-treatments like weld overlaying or melting and solidification.
Innovation Solution
The method involves indenting the transverse ends of a clad steel strip to form a groove before welding, using a shielding gas with specific conditions to reduce oxygen concentration and prevent penetrator formation, and controlling the amount of upset to prevent base metal exposure, thereby reducing the weld width without post-treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of upset is increased during electric resistance welding to discharge oxidized melts, then penetrators are prevented from remaining in the weld, but the base metal is exposed at the cladding metal-side surface, degrading corrosion resistance
Solution Approach 1:
The patent applies preliminary action by forming a groove at the butted parts of the clad steel strip before welding. This groove is created by indenting the transverse ends, which prepares the geometry in advance to control metal flow during welding. The groove ensures that when upset is applied to discharge oxidized melts, the base metal remains contained and does not expose at the cladding metal-side surface, thus preventing degradation of corrosion resistance while still achieving weld strength.
2Strength
If the width of the weld metal is reduced by using electric resistance welding, then the mechanical properties of the weld are improved, but oxide-based penetrators occur in the weld, degrading toughness and strength
Solution Approach 1:
The patent applies the inert atmosphere principle by introducing a shielding gas environment during electric resistance welding. The shielding gas prevents oxidation of the metal at the weld zone, thereby preventing the formation of oxide-based penetrators. This allows the weld to maintain both high strength (through reduced weld width) and high toughness (by eliminating oxide inclusions that would degrade mechanical properties).
Solution Approach 2:
The groove formation before welding serves as preliminary action to control the welding process. The pre-formed groove geometry ensures proper metal flow and oxidation discharge during welding, working in conjunction with the shielding gas to prevent penetrator formation while maintaining weld integrity and mechanical properties.
3Reliability
If post-treatment such as weld overlaying or melting and solidification is performed to remove penetrators, then the mechanical properties of the weld are improved, but the production complexity and time are increased
Solution Approach 1:
The patent converts the potential harm of oxidized melts into a benefit by controlling their discharge. Instead of allowing oxidized melts to remain as harmful penetrators, the process uses the upset mechanism to deliberately discharge them through the groove, while the shielding gas prevents new oxidation. This eliminates the need for post-treatment removal operations, simplifying the production process while maintaining weld quality.
Solution Approach 2:
The welding process itself performs the function of removing oxidized melts through the upset mechanism, eliminating the need for separate post-treatment operations. The groove geometry and shielding gas work together during the welding process to self-cleanup the weld zone, discharging oxidized melts and preventing penetrator formation without requiring additional overlaying or melting steps.
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 results in a clad welded pipe or tube with improved mechanical properties and corrosion resistance by minimizing the weld width and preventing base metal exposure, maintaining the clad pipe's functionality without the need for post-treatments like weld overlaying or melting and solidification.
Implementation Method 1
subjecting the pair of butted parts to gas shielding during electric resistance welding
Implementation Method 2
electric resistance welding a pair of butted parts of the open pipe or tube
Data Source
AI summary
Provided is a clad welded pipe or tube that has improved pipe or tube mechanical properties by reducing the width of a weld without its function as a clad pipe or tube being impaired. A clad welded pipe or tube comprises: a first layer made of base metal; and a second layer placed on one surface of the first layer, and made of first cladding metal that is a material different from the base metal, wherein a pipe or tube circumferential length L1 of weld metal at a pipe or tube inner surface and a pipe or tube circumferential length L2 of the weld metal at a pipe or tube outer surface in a weld are each 0.0010 mm or more and 1.0 mm or less, and the base metal is not exposed at a first cladding metal-side surface of the clad welded pipe or tube in the weld.