Bimetallic Lined Pipe Bonding to Prevent Liner Slippage
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Solution Overview
Problem
Bimetallic mechanically-lined pipes face challenges such as wasteful cutting of expensive CRA material, slippage of the liner sleeve, and leakage issues during reel-lay operations due to plastic deformation and buckling, which increase costs and reduce the effectiveness of subsea pipeline installation.
Innovation Solution
Friction stir welding (FSW) is used to bond the CRA liner sleeve to the carbon steel outer pipe, forming a thermo-mechanically affected zone along a weld path in the previously unbonded outboard region, eliminating the need for expensive machining and filler materials, and ensuring a secure mechanical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hydraulic expansion is used to bond the liner sleeve to the outer pipe, then the bonding process is simple and cost-effective, but the liner sleeve slips and buckles during reel-lay operations due to plastic deformation
Solution Approach 1:
The liner sleeve bonding is divided into two distinct zones: an inboard region with hydraulic expansion bonding and an outboard region with friction stir welding bonding. This segmentation allows each zone to serve a specific function - the inboard region provides initial mechanical bonding while the outboard region prevents slippage during reel-lay operations.
Solution Approach 2:
The invention combines two different bonding methods - hydraulic expansion and friction stir welding - into a single liner sleeve assembly. The friction stir welded overlay is applied to the outboard region of the liner sleeve, merging the advantages of both bonding techniques to achieve both ease of manufacture and operational reliability.
2Loss of substance
If the liner sleeve is mechanically bonded without metallurgical bonding, then material costs are reduced, but cutting of expensive CRA material is required at the ends
Solution Approach 1:
The friction stir welded overlay is applied to the outboard region of the liner sleeve before final assembly and reel-lay operations. This preliminary action eliminates the need for subsequent cutting and machining of the liner sleeve ends, as the overlay provides sufficient bonding and structural integrity.
Solution Approach 2:
The invention changes the bonding mechanism in the outboard region from mechanical interference fit to metallurgical bonding via friction stir welding. This parameter change allows the liner sleeve to maintain its full length without requiring cutting, while still achieving reliable bonding to the outer pipe.
3Ease of manufacture
If friction stir welding is used to bond the liner sleeve to the outer pipe, then material and labor costs are reduced with simplified manufacturing, but the process complexity increases
Solution Approach 1:
The friction stir welding process is designed to be self-contained, with the welding tool performing all necessary functions - heating, stirring, and forging - in a single pass. The process eliminates the need for separate heating, cooling, and finishing operations that would otherwise be required, simplifying the overall manufacturing workflow despite the advanced welding technology.
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 reduces material and labor costs, simplifies the manufacturing process, enhances the quality and repeatability of the bonding, and prevents slippage and leakage, thereby improving the reliability and efficiency of bimetallic lined pipe joints.
Implementation Method 1
driving the FSW tool, when spinning about a spin axis, into the liner sleeve to form a thermo-mechanically affected zone (TMAZ) in which metal of the liner sleeve is bonded with metal of the host pipe
Implementation Method 2
both the liner sleeve and the outer pipe are expanded radially by internal hydraulic pressure applied to the liner sleeve
Data Source
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AI summary
A liner sleeve is secured within a host pipe of a bimetallic lined pipe by driving a spinning friction stir welding tool through the liner sleeve but not through the full wall thickness of the host pipe. This forms a thermo-mechanically affected welded zone in which metal of the liner sleeve is bonded with some metal of the host pipe. Relative movement between the spinning tool and the lined pipe extends the welded zone along a weld path. Where the pipe is mechanically lined, the welded zone extends along a previously unbonded outboard region that extends longitudinally from an inboard region at which the liner sleeve is bonded mechanically to the host pipe.