Underwater Pipe End Lining and Weld Joint for Corrosive Fluids
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Solution Overview
Problem
Existing methods for assembling underwater pipes to transport corrosive fluids, such as seawater or hydrocarbons, face challenges in ensuring reliable sealing, corrosion resistance, fatigue resistance, and mechanical performance while minimizing the number of welds and avoiding complex, costly tubular junction sleeves.
Innovation Solution
A method involving the application of a corrosion-resistant steel alloy layer on the internal wall of pipe elements, followed by a thermoplastic lining and a compression ring with corrugated annular parts for sealing and anchorage, allowing direct welding of pipe ends with a single corrosion-resistant steel alloy weld, eliminating the need for tubular junction sleeves and additional steel connecting pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tubular junction sleeves of anti-corrosion material are used to ensure continuity of protective coating at pipe ends, then sealing and corrosion protection are improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the tubular junction sleeve from the system by extending the thermoplastic liner continuously through the weld zone using a spool piece. This removes the complex intermediate component while maintaining the protective function through a simplified continuous liner configuration.
Solution Approach 2:
The invention merges the functions of the tubular junction sleeve and the thermoplastic liner into a single continuous liner system. The liner is extended through the weld area and anchored to the spool piece, combining what were previously separate protective elements into one integrated solution.
2Reliability
If multiple welds with anti-corrosion steel alloy and steel connecting pieces are used, then corrosion resistance and sealing are improved, but the number of welds increases and assembly complexity increases
Solution Approach 1:
The invention merges multiple separate welding operations into a single weld between two spool pieces. The thermoplastic liner is removed from the weld zone, allowing direct welding of the spool pieces without requiring anti-corrosion steel alloy coatings or multiple weld passes, thereby reducing both the number of welds and assembly complexity.
Solution Approach 2:
The spool piece acts as an intermediary component that provides a clean, unlined surface for welding. By positioning the spool piece at the end of each pipe element, it serves as a mediator that allows the thermoplastic liner to be discontinuous at the weld zone while maintaining protection elsewhere, simplifying the welding process.
3Reliability
If anti-corrosion steel alloy coating is applied at pipe ends before welding, then corrosion resistance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention extracts and removes the anti-corrosion steel alloy coating requirement from the weld zone by using a spool piece with a discontinuous liner configuration. This eliminates the need for complex coating applications at pipe ends, as the spool piece provides a suitable welding surface without requiring additional corrosion-resistant coatings.
Solution Approach 2:
The spool piece acts as a temporary, disposable component that simplifies manufacturing. Rather than applying expensive anti-corrosion coatings to pipe ends, the spool piece provides a simple, unlined surface for welding, reducing manufacturing complexity and cost while the liner extends to the spool piece to maintain corrosion protection.
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 method provides reliable sealing, corrosion protection, and resistance to fatigue with reduced mechanical resistance impact and fluid head losses, while simplifying the assembly process and reducing costs by minimizing the number of welds and eliminating the need for complex tubular junctions.
Implementation Method 1
a first annular part of length L4 of the compression ring to be crimped against a pressure side face of the terminal part of the protective coating of plastic material
Implementation Method 2
an outer side face which is corrugated, over a part at least of its length, preferably in the form of a plurality of first parallel circular peripheral grooves
Implementation Method 3
the welding of the free end of a second annular part of the compression ring against a second part of said layer of corrosion-resistant steel alloy
Data Source
AI summary
A method for producing a steel underwater pipe for carrying a corrosive fluid, includes the successive steps: applying a layer of corrosion-resistant steel alloy on a terminal part of the internal wall of each pipe element from its end to be welded; the application of a plastic coating, on the internal wall of each pipe element; covering only a first part of the layer of metal alloy, a terminal part of the layer of metal ally on the side of the end to be welded of each pipe element not being covered by the plastic coating; the coaxial insertion and the crimping of a compression ring against the terminal part of the plastic coating; and the assembly by welding directly together the ends of two pipe elements by a corrosion-resistant steel alloy weld.