Welded Piping Joint Structure Without Back Shielding
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Solution Overview
Problem
Conventional piping joint structures require large amounts of inert gas for back shielding to prevent oxidation on the inner surface of pipes during butt welding, which is costly and inefficient, especially in complex or long piping routes, leading to oxidized scale formation and increased construction times.
Innovation Solution
A piping joint structure that eliminates the need for back shielding by forming V-shaped bevels on the tubular materials, allowing inert gas welding from the outer surface while maintaining a sealed internal edge, preventing oxidation and reducing gas consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If back shielding is performed to prevent oxidation on the inner surface side, then oxidation prevention is improved, but inert gas consumption and cost increase significantly
Solution Approach 1:
The piping system is divided into segments with fitting portions at connection points. These fitting portions act as barriers to segment the internal space, preventing oxidized scale formation while limiting inert gas requirement to only the welding zone rather than the entire pipe length.
Solution Approach 2:
The fitting portion serves as an intermediary structure between the two tubular materials. It provides a mechanical connection while also functioning as a barrier to oxidation, eliminating the need for back shielding in long or complex piping routes.
2Reliability
If back shielding is performed to prevent oxidation, then oxidation prevention is improved, but construction time and complexity increase
Solution Approach 1:
The fitting portions are pre-formed on the tubular materials before welding. This preliminary preparation creates the oxidation barrier structure in advance, eliminating the need for time-consuming back shielding operations during the welding process itself.
Solution Approach 2:
The back shielding operation is extracted and eliminated from the welding process. The fitting portions provide passive oxidation prevention without requiring active inert gas filling and management, significantly reducing construction time and operational complexity.
3Reliability
If complex or long piping routes are welded with back shielding, then oxidation prevention is improved, but the difficulty and cost increase
Solution Approach 1:
Complex piping routes are divided into manageable segments by fitting portions at each connection point. Each fitting portion independently provides oxidation prevention, making the overall system manageable regardless of length or complexity without requiring continuous back shielding.
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 solution reduces costs by minimizing inert gas usage, shortens construction and repair times, and prevents oxidized scale from contaminating downstream components like power turbines, enhancing assembly efficiency and safety.
Implementation Method 1
a method of inert gas welding from the outer peripheral surface side is used, in which the welding is performed in a state in which air is excluded from the weld zone by an inert gas such as helium gas, argon gas, or the like
Implementation Method 2
so-called back shielding is performed in which the whole pipe is filled with an inert gas such as helium gas, argon gas, or the like
Implementation Method 3
an end of the second tubular material and an end of the third tubular material, which is located adjacent to the second tubular material, are joined by butt welding
Data Source
AI summary
An object is to provide a piping joint structure (10;20;30;50) that enables welding without back shielding, and in which oxidized scale does not occur on the inner surface side of the pipe. In a piping joint structure in which an end of a first tubular material (12;24;32;52) and an end of a second tubular material (13;25;33;53), which is located adjacent to the first tubular material, are joined by butt welding, an inner fitting portion (14a;24a;34a;54a) is formed around the circumference on the end of the first tubular material, and a first bevel (14b;24b;34b;54b) is formed on the radial outside of the inner fitting portion around the circumference, an outer fitting portion, which is fitted to the radial outside of the inner fitting portion, is formed on the end of the second tubular material, and a second bevel (15b;25b;35b;B) is formed around the circumference at a location that is at the end of the outer fitting portion and that faces the first bevel.