Process Pipe Liner With Thermal Buffer Against Fatigue Cracking
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Solution Overview
Problem
High cycle thermal fatigue in high temperature process pipes, particularly in areas with rapid temperature fluctuations and corrosive fluids, leads to crack initiation and propagation, resulting in costly repairs or replacements, as existing methods fail to effectively mitigate thermal stresses and corrosion.
Innovation Solution
A liner is inserted into the process pipe to create a gap between the pipe and the liner, reducing heat transfer and thermal loading, comprising segments connected by joints that allow movement and made from materials like carbon steel, stainless steel, or nickel-based alloys, with spacers and expansion joints to maintain a thermal buffer and prevent fluid communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the liner is tightly fitted to the pipe, then structural support is improved, but heat transfer increases and thermal fatigue is not mitigated
Solution Approach 1:
The liner is divided into multiple segments (first liner segment, second liner segment, etc.) that are positioned at different locations within the pipe. This segmentation allows the liner to provide structural support at key locations while maintaining gaps in other areas to reduce heat transfer and mitigate thermal fatigue.
Solution Approach 2:
The liner acts as an intermediary element between the corrosive process fluid and the pipe wall. It provides corrosion protection while the controlled gaps between the liner and pipe wall allow thermal insulation, thus mediating between the need for structural integrity and thermal protection.
2Reliability
If the liner is loosely inserted to reduce heat transfer, then thermal fatigue is mitigated, but structural support and fluid containment are weakened
Solution Approach 1:
The liner system is segmented into multiple sections that can be independently positioned. Some segments are placed in areas requiring structural support, while gaps are maintained in areas where thermal insulation is most beneficial for preventing thermal fatigue.
Solution Approach 2:
Different regions of the pipe receive different levels of liner coverage based on local requirements. Areas subject to high thermal fatigue stress maintain larger gaps for insulation, while areas requiring structural support have tighter liner fit or additional support features.
3Strength
If weld overlay is applied to the outside of pipe sections, then crack propagation is addressed, but corrosion resistance is not improved and costs increase
Solution Approach 1:
The corrosion protection function is extracted from the pipe wall itself and transferred to the liner element. The liner is made from corrosion-resistant materials and positioned inside the pipe to provide a protective barrier, separating the corrosive fluid from the pipe wall and eliminating the need for corrosion-resistant pipe materials or weld overlays.
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 liner significantly reduces thermal loading on the pipe, preventing cracking and extending its lifespan by creating a thermal buffer that minimizes heat transfer and reduces the impact of thermal gradients and corrosive effects.
Implementation Method 1
the liner sized to provide a gap between an outer wall of the liner and an inner wall of the pipe... decrease the rate of heat transfer between the process fluids flowing through the liner and the pipe
Data Source
AI summary
Provided herein is a liner that can be loosely inserted in process pipe to form a lined pipe and to decrease the rate of heat transfer between process fluids flowing through the liner and the process pipe. The liner provided herein can reduce applied thermal loading on the outer pipe resulting from, for example, turbulent mixing between fluids having different temperatures (with or without stratification), circumferential thermal gradients, and/or longitudinal thermal gradients. An annulus between the process pipe and liner can be at least partially filled by process fluids, thereby creating a thermal buffer to further decrease the rate of heat transfer between the fluids and the process pipe.