Multilayer Pipe Mechanical Expansion Bonding Process
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing multilayer pipes, such as clad and lined pipes, require multiple thermal treatment and forming steps, making them costly and inefficient, especially for producing seamless pipes with desired quality.
Innovation Solution
A process involving mechanical expansion of seamless inner and outer pipes, where the inner pipe is inserted into the outer pipe, with a mandrel providing relative longitudinal movement, and optional chemical preparation and heating steps to achieve a mechanical or metallurgical bond without additional thermal treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple thermal treatment and forming steps are used to produce multilayer pipes, then the quality and bond strength are improved, but the production cost and process complexity increase
Solution Approach 1:
The patent combines multiple separate operations (insertion of inner pipe into outer pipe, expansion, and bonding) into a single integrated mechanical expansion step. The mandrel simultaneously expands the inner pipe and creates the mechanical interlock with the outer pipe, eliminating the need for separate thermal treatment and forming steps while maintaining bond quality.
Solution Approach 2:
The patent extracts and eliminates the thermal treatment step from the traditional multilayer pipe production process. By using purely mechanical expansion through a mandrel, the process achieves bonding without heating or thermal cycles, thereby reducing process complexity and cost while maintaining manufacturing precision.
2Reliability
If traditional cladding processes are used, then corrosion resistance is achieved, but production time and cost increase
Solution Approach 1:
The patent skips the traditional multi-step cladding process by directly inserting the inner pipe into the outer pipe and achieving bonding through mechanical expansion alone. This eliminates intermediate steps such as separate heating, bonding, and cooling phases, thereby maintaining corrosion resistance while significantly improving production efficiency.
3Manufacturing precision
If seamless pipes are produced using current methods, then high quality is achieved, but additional welding or thermal steps are required
Solution Approach 1:
The patent segments the pipe production into two separate seamless pipes (inner and outer) that are subsequently assembled through mechanical expansion. This segmentation allows each pipe to be manufactured separately as seamless pipes, maintaining high quality while avoiding the need for additional welding or thermal steps that would compromise the seamless structure.
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 process reduces production efforts and costs while ensuring high-quality multilayer pipes with mechanical or metallurgical bonds, meeting industry standards for corrosion resistance and mechanical strength, and allows for seamless pipe production without additional welding or thermal steps.
Implementation Method 1
at least one mechanical expansion step, comprising providing a relative movement between a mandrel and the mounted pipes in the longitudinal direction
Implementation Method 2
the inner pipe having an elastic return smaller than the elastic return of outer pipe when both are deformed
Implementation Method 3
a heating step by induction of the outer and inner pipes, synchronizedly with a mechanical expansion step
Implementation Method 4
a chemical preparation step is performed in the following sequence: acid pickling of at least the inner surface of the inner pipe; neutralizing and washing of the at least the inner surface of the inner pipe
Data Source
AI summary
A process for producing a multilayer pipe by expansion is disclosed, with or without heating, in which a multilayer pipe (1) comprises at least one outer pipe of metallic material (10) and an inner pipe of metallic material (20), the inner pipe of metallic material (20) having a yield strength lower than the yield strength of the outer pipe (23) and an external diameter smaller than the internal diameter of the outer pipe. The process for producing the multilayer pipe comprises a mounting step (34) between the pipes (10, 20), wherein the inner pipe is inserted inside the outer pipe, and at least one mechanical expansion step (36), comprising moving a mandrel (2) longitudinally and internally in the inner pipe (20) while the outer pipe and the inner pipe are held at a fixed position, wherein at least part of the mandrel (2) has a greater external diameter than the internal diameter of the inner pipe. When the pipes are subjected to a process of cold expansion, a “lined pipe” is obtained, which is characterized by mechanical bonding between the pipes. When the pipes are subjected to a process of hot expansion, a “clad pipe” is obtained, which is characterized by metallurgical bonding between the pipes.