Plated Steel Pipe Weld Edge Shaping for Corrosion Resistance
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Solution Overview
Problem
The corrosion resistance in the weld zone and its vicinity of electric resistance welded steel pipes, originally made from plated steel sheets, degrades due to evaporation of plating components during welding and removal of plating layers, necessitating post-repair which may not fully restore corrosion resistance.
Innovation Solution
The method involves shaping the end faces of a plated steel sheet with inclined portions to minimize the width of the weld bead, applying a plated layer to cover the end faces, and controlling the bead width during welding to less than 92% of the sheet thickness, followed by applying plating materials to the weld zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If welding is performed on plated steel sheet, then steel pipe is formed, but corrosion resistance degrades due to plating evaporation and removal
Solution Approach 1:
The end faces of the plated steel sheet are shaped with inclined portions before welding to minimize bead width. This preliminary geometric preparation reduces the amount of plating removed during subsequent welding and bead removal, thereby maintaining corrosion resistance while enabling efficient pipe production.
Solution Approach 2:
Plating materials are selectively applied to the weld zone after welding to restore corrosion resistance locally where it was degraded. This targeted repair approach addresses the corrosion issue at the specific affected area without requiring complete re-plating of the entire pipe.
2Shape
If bead is removed after welding, then weld appearance is improved, but plating layers are also removed exposing steel substrate
Solution Approach 1:
The end faces are pre-shaped with inclined portions to minimize the width of the weld bead generated during welding. This preliminary geometric preparation ensures that the bead width is reduced before the welding process, thereby minimizing the subsequent bead removal required and preserving more plating material.
Solution Approach 2:
After bead removal, the removed plating materials are recovered and reapplied to the weld zone through post-weld plating processes. This allows the steel substrate to be protected again, restoring corrosion resistance in the areas where plating was removed during bead removal.
3Reliability
If post-repair plating is applied, then corrosion resistance is partially restored, but it cannot be recovered to the same extent as other portions
Solution Approach 1:
The end faces are pre-shaped with inclined portions before welding to minimize bead width and reduce the extent of plating removal. This preliminary action reduces the area requiring post-repair plating, thereby maintaining corrosion resistance with minimal additional processing and preserving production efficiency.
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 inhibits the degradation of corrosion resistance in the weld zone and its vicinity by reducing the exposed substrate area and minimizing the need for post-repair, thereby enhancing the overall corrosion resistance of the steel pipe.
Implementation Method 1
places in and around a weld zone are locally subjected to a high temperature, leading to the evaporation of plating components
Implementation Method 2
performing electric resistance welding in such a way that a butt angle between the strip-material vertical end faces is within the range of ±1 degree
Data Source
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AI summary
Provided is a production method of an electric resistance welded steel pipe, including: an end face-shaping step of forming, on each of a first end face and a second end face on both sides in a width direction of a plated steel sheet, an outer inclined portion inclined in a sheet-thickness direction from a side of an outer surface toward a side of an inner surface or forming the outer inclined portion and an inner inclined portion inclined in the sheet-thickness direction from the side of the inner surface toward the side of the outer surface, the first end face and the second end face each being shaped in such a way that a sheet thickness decreases from a center in the width direction toward the end face; and a pipe-making step of welding the first end face and the second end face both undergone shaping end to end to make a pipe. Accordingly, in an electric resistance welded steel pipe, the original of which is a plated steel sheet, the degradation of corrosion resistance in the weld zone and its vicinity is inhibited.