Lined Pipe Joint Structure for Heat-Safe Butt Welding
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Solution Overview
Problem
Existing methods for joining lined pipes during welding often damage the non-metallic liner due to heat generation, and require complex couplers or flared ends, which increase the pipe assembly's diameter and depend on precise alignment for effective welding.
Innovation Solution
A lined pipe assembly comprising a metallic pipe, a tubular metallic coupler, a tubular metallic sleeve, and a non-metallic liner, where the coupler and sleeve are designed to minimize heat transfer to the liner during welding, and a collar is used to align the couplers for welding while circulating a cooling fluid through an annular space to reduce heat buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If couplers are used to join lined pipes during welding, then the pipes can be connected, but the non-metallic liner is damaged or delaminated due to heat generation
Solution Approach 1:
A heat-resistant material (such as ceramic or refractory material) is introduced as an intermediary between the welding zone and the non-metallic liner. This intermediary material acts as a thermal barrier, absorbing and reflecting heat away from the liner during the welding process, thereby preventing heat damage and delamination while allowing the welding operation to proceed
Solution Approach 2:
The coupler structure is segmented into distinct functional zones: an outer welding zone for joining metal pipes, an intermediate heat-resistant material layer for thermal protection, and an inner zone for liner accommodation. This segmentation allows each zone to perform its specific function independently, protecting the liner from heat while enabling effective welding
2Reliability
If flared-out ends are provided on metal tubes, then heat shield collar can be inserted, but the device complexity increases
Solution Approach 1:
The coupler is designed as a universal component that performs multiple functions: it provides structural support for joining pipes, incorporates heat-resistant material for thermal protection, and includes alignment features for precise positioning. By integrating these functions into a single multi-functional component, the overall device complexity is reduced compared to using separate flared ends and heat shield collars
3Manufacturing precision
If precise alignment of coupler ends is required for welding, then welding quality improves, but the alignment process becomes more difficult
Solution Approach 1:
Alignment features such as radial protrusions and grooves are pre-formed on the coupler components during manufacturing. These preliminary structural features automatically guide and constrain the relative positioning of coupler ends during assembly, ensuring precise alignment is achieved through the natural mating of these features rather than requiring complex external alignment procedures
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
The solution effectively protects the non-metallic liner from heat damage during welding, reduces the overall diameter of the pipe assembly, and simplifies the alignment process for efficient butt welding, while maintaining the integrity of the liner.
Implementation Method 1
circulating a cooling fluid through an annular space to reduce heat buildup
Implementation Method 2
designed to minimize heat transfer to the liner during welding
Data Source
AI summary
A lined pipe assembly includes a metallic pipe and a tubular metallic coupler. The coupler is welded to the pipe and includes a coupler inner wall defining a coupler internal profile. A tubular metallic sleeve is pressed fit into the coupler internal profile. An outer wall of the sleeve and a proximal portion of the coupler inner wall define an annular space therebetween. A non-metallic liner lines an inner wall of the pipe, a distal portion of the coupler inner wall, and an inner wall of the sleeve. To join a pair of the lined pipe assemblies, a tubular collar is provided inside the first and second couplers to abut against bearing surfaces of the couplers, and define an annular space between an inner wall of the collar and outer walls of the pipes. The pipes are then welded at a location that axially overlaps the collar.