Undersea Pipe Joint Welding With Compressive Sanded Beads
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Solution Overview
Problem
The existing methods for connecting steel catenary risers, such as J-lay and S-lay techniques, are time-consuming and often result in unacceptable weld quality, requiring grinding and manual inspection, which can lead to remakes and inefficiencies in fatigue strength due to high dynamic stress and deformation.
Innovation Solution
A method involving three distinct weld beads followed by controlled sanding to apply compression stresses, eliminating the need for grinding and improving fatigue strength by at least 300% through enhanced crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If grinding operation is performed on weld beads to eliminate geometrical discontinuities, then manufacturing precision is improved, but loss of time increases and productivity decreases
Solution Approach 1:
The invention extracts and eliminates the grinding operation from the welding process sequence. By using a welding technique that produces weld beads without significant geometrical discontinuities, the harmful grinding step is removed entirely, reducing connection time while maintaining weld quality.
Solution Approach 2:
The invention skips the grinding operation by using a welding method that directly produces acceptable weld geometry. The welding parameters and technique are optimized to create weld beads that meet quality standards without requiring subsequent mechanical removal of material.
2Manufacturing precision
If manual inspection is performed on weld beads to verify quality, then manufacturing precision is improved, but loss of time increases and productivity decreases
Solution Approach 1:
The welding process is designed to be self-verifying, where the welding parameters and technique inherently produce consistent, high-quality weld beads. The process controls and procedure design ensure quality without requiring external manual inspection intervention.
Solution Approach 2:
The invention skips the manual inspection step by using a welding method that produces consistently acceptable results. The welding technique and parameters are controlled to eliminate the need for subsequent verification, allowing the process to move directly to the next operation.
3Strength
If three distinct weld beads are deposited with controlled sanding, then fatigue strength is improved by 300%, but device complexity increases
Solution Approach 1:
The welding process is segmented into three distinct weld beads deposited in sequence, with controlled sanding between passes. This segmentation allows each weld bead to be optimized for specific functions: the first two beads provide base strength while the third bead, followed by sanding, creates compressive stresses that dramatically improve fatigue resistance.
Solution Approach 2:
The invention changes the welding parameters and sequence to deposit three distinct weld beads with specific characteristics. The controlled sanding operation between and after welding passes modifies the surface geometry to create beneficial compressive stress fields, transforming the weld structure to enhance fatigue strength by 300%.
4Manufacturing precision
If grinding operation is performed on weld beads, then manufacturing precision is improved, but ease of manufacture worsens due to additional operations
Solution Approach 1:
The invention extracts and eliminates the grinding operation from the welding process. By using a welding technique that produces weld beads with acceptable geometry directly, the harmful and complex grinding step is removed, simplifying the overall connection process while maintaining weld quality.
Solution Approach 2:
The invention skips the grinding operation by using optimized welding parameters and technique that produce weld beads meeting quality standards in a single continuous process, eliminating the need for subsequent mechanical finishing operations.
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 method significantly improves the fatigue lifetime of undersea fluid transport pipes by reducing crack initiation and propagation, and simplifies the connection process by eliminating grinding operations while ensuring high adhesion for protective coatings.
Implementation Method 1
controlled sanding of the weld beads in order to apply compression stresses on them
Implementation Method 2
welding being done by making three distinct weld beads
Data Source
AI summary
A method of connecting together two unit elements (2, 4) of an undersea fluid transport pipe that is subjected to fatigue, by welding together two metallic or bi-metallic unit pipe elements that have been put into abutment via their respective free ends (2a, 4a), the welding being done by making three distinct weld beads (6, 8, 10), with a last weld bead (8) being deposited between two lateral first weld beads (6, 10), and being followed directly by controlled sanding of the weld beads in order to apply compression stresses on them.