Electrofusion Connecting Sleeve for Sealed Lined Pipe Joints
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Solution Overview
Problem
Existing methods for assembling steel pipes with internal plastic liners face challenges in ensuring waterproof sealing, particularly at the junctions, which can lead to corrosion and leaks due to the heterogeneity of materials and mechanical stress from ocean currents and swell, especially in deep-sea applications.
Innovation Solution
A tubular junction sleeve made of thermoplastic material with a double spiral heating wire configuration is inserted between the pipe elements, ensuring a complete and reliable sealing by fusion welding, avoiding electrical short circuits and allowing for uniform electrofusion, and using a constricted sleeve design with thermal protection to prevent deformation during welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sleeve material is made homogeneous with the liner, then sealing reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The sleeve is segmented into three distinct portions along its length: two reduced thickness terminal portions at the ends and a constant thickness intermediate portion in the middle. This segmentation allows each section to be optimized for its specific function while maintaining overall manufacturing feasibility through a single-mold injection process.
Solution Approach 2:
Different portions of the sleeve have different thicknesses tailored to their specific functions. The terminal portions have reduced thickness to allow deformation and sealing contact with the liner, while the intermediate portion has constant thickness to provide structural strength and corrosion protection. This local quality variation is achieved through optimized mold design rather than complex assembly processes.
2Reliability
If the sleeve has reduced thickness terminal portions, then sealing capability is improved, but structural strength deteriorates
Solution Approach 1:
The sleeve features local quality variation with reduced thickness at terminal portions and constant thickness in the intermediate portion. This allows the terminal sections to deform and seal effectively with the liner while the thicker intermediate section maintains structural strength for corrosion protection and mechanical support.
Solution Approach 2:
The thickness parameter is strategically varied along the sleeve length. The terminal portions have reduced thickness to enable sealing deformation, while the intermediate portion maintains full thickness for structural integrity. The material composition and geometric parameters are optimized to ensure the reduced thickness sections still provide adequate strength for their sealing function.
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 provides a mechanically reliable and cost-effective method for assembling steel pipes with internal liners, ensuring waterproof sealing and preventing corrosion, even under high pressure and extreme environmental conditions, with reduced risk of weld failure and material deformation.
Implementation Method 1
a Joule heating wire, arranged in a spiral on the external surface of each said terminal part at the ends of the sleeve
Implementation Method 2
said sealed contact zone being a zone of fusion welding between the constituent materials of each said terminal part of the sleeve and respectively each said terminal part of said cladding in contact with each other
Data Source
Figure 1
Figure 1A~1D
Figure 2~2B
AI summary
The present invention relates to a pipe (1) comprising at least 2 steel pipe elements (11, 12) with internal liner (2) which are assembled end to end, in which the ends of the two pipe elements are welded (5) together. A tubular connecting sleeve (3) is interposed inside the pipe at the butt-jointed ends of the two pipe elements so that the terminal end parts (3a, 3b) of said sleeve are, at least in part, in fluidtight contact (4-1) respectively with the terminal parts (2a, 2b) at the ends of the said internal liners of the two pipe elements. The said fluidtight area of contact (4-1) is a zone in which the constituent materials of at least part of each said terminal part (3a, 3b) of the sleeve and each respective said terminal part (2a, 2b) of said liner in contact with one another are welded together by fusion. Said tubular connecting sleeve has, at each of said terminal parts (3a, 3b) of the sleeve in the region of said area of fluidtight contact, a joule-effect heating wire (6) laid in a double spiral on the external surface of each said terminal part at the ends of said sleeve.