Additive Return Bend Geometry for Compact Fire Tube Connections
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Solution Overview
Problem
Fire tubes in heater treaters and furnaces face challenges in connecting parallel tubes due to small center-center distances, leading to stress-prone mitered welds that are difficult to weld and inspect, and are prone to failure.
Innovation Solution
Utilizing additive manufacturing to create a continuous, smooth-curvature return bend that eliminates mitered joints, allowing for customizable shapes, materials, and variable thicknesses to enhance durability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mitered bends are used to connect parallel tubes with small center-center distance, then the connection can be achieved with conventional manufacturing methods, but the welds are subject to high stress and prone to failure
Solution Approach 1:
The patent applies smooth curved transitions instead of angular mitered joints to connect parallel tubes. The continuous curvature eliminates sharp corners and stress concentration points, creating a more reliable connection that withstands thermal and mechanical stresses without weld failure.
Solution Approach 2:
The invention merges multiple tube sections into a single continuous bent tube structure, eliminating the need for separate welding joints. This integration removes the weak points associated with mitered welds while maintaining the compact center-center distance between parallel tube ends.
2Ease of manufacture
If mitered bends are used to connect tubes, then conventional manufacturing can be employed, but the bends are difficult to weld or inspect particularly at the intrados
Solution Approach 1:
The smooth curved geometry of the bent tube provides uniform surface accessibility throughout the structure. Unlike mitered bends with hidden intrados regions, the continuous curvature allows welding and inspection equipment to access all surfaces equally, eliminating difficult-to-reach areas.
3Length of stationary object
If standard short-radius return bend is used, then conventional manufacturing is simple, but the center-center distance between parallel tubes is too small to permit its use
Solution Approach 1:
The patent utilizes additive manufacturing to achieve precise control over geometric parameters, including the bend radius and tube center-center distance. This enables customization of the return bend geometry to fit compact spaces while maintaining structural integrity and smooth curvature.
Solution Approach 2:
The invention transitions from standard two-dimensional return bend profiles to three-dimensional customizable geometries enabled by additive manufacturing. This allows optimization of the bend path and radius to achieve the required compact center-center distance while maintaining smooth transitions.
Data Source
AI summary
A return bend for use in a heater treater, production separator, or furnace is designed to join adjacent tubes. The return bend includes a pipe constructed in a continuous piece. The pipe includes: a first end forming a first opening of the pipe facing a first direction; a second end opposite the first end, the second end forming a second opening facing the first direction; and at least one curving section that bends with a continuously smooth curvature of the pipe wall from the first end to the second end.