Cylindrical Thermal Sheath for Cable Protection
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Solution Overview
Problem
Conventional thermal insulation systems fail to protect elongated structural elements, such as post-tensioning cables and stay cables, from extreme thermal loading scenarios exceeding 1000°C, leading to steel relaxation, tendon failure, and anchorage slippage, which compromises the structural safety of civil engineering structures during fires.
Innovation Solution
A cylindrical thermal protection sheath with a sandwich-like composite insulation system having a thermal conductivity lower than 0.11 W/m°C at 800°C and a thickness less than 50 millimeters, designed to accommodate the elongated shape and movements of cables, featuring layers of reflective fabric, high-strength thermal fabric, fibrous ceramic wool, micro-porous thermal insulation material, and a durable inner layer for enhanced protection and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional thermal insulation systems are used, then the insulation thickness can be reduced, but the thermal protection against extreme temperatures exceeding 1000°C is insufficient
Solution Approach 1:
The patent employs a multi-layer composite insulation system consisting of different material layers (including ceramic fiber, refractory cement, and protective coatings) that work synergistically to achieve superior thermal protection at reduced thickness. Each layer serves a specific function: thermal insulation, structural support, and fire resistance, collectively providing protection against temperatures exceeding 1000°C while maintaining a compact profile.
Solution Approach 2:
The invention utilizes materials with temperature-dependent thermal conductivity properties that change phase or structure at critical temperature thresholds. The insulation system incorporates materials that maintain low thermal conductivity even at extreme temperatures, and the protective coating undergoes intumescence (volume expansion) when exposed to fire, creating an additional insulating barrier that enhances thermal protection dynamically.
2Adaptability or versatility
If the sheath accommodates cable movements and elongated shape, then the adaptability improves, but the structural integrity under thermal loading may be compromised
Solution Approach 1:
The sheath incorporates flexible joints and expansion compartments that allow the structure to dynamically adapt to cable movements, thermal expansion, and sag variations. The insulation layers are designed with controlled flexibility, using materials that can bend and flex without compromising their thermal insulation properties, enabling the sheath to move with the cable while maintaining protective function.
Solution Approach 2:
The sheath is divided into multiple segmented sections connected by flexible joints, allowing each segment to move independently to accommodate cable movements. This segmentation maintains overall structural integrity while providing adaptability, as the modular design allows the sheath to flex and conform to changing cable positions without creating stress concentrations that would compromise strength.
3Weight of moving object
If a thin insulation system is used, then the weight and wind drag are reduced, but the thermal protection duration at extreme temperatures is insufficient
Solution Approach 1:
The thin-walled sheath utilizes advanced composite materials with high strength-to-weight ratios, combining lightweight structural supports with high-performance insulation layers. This composite construction achieves adequate thermal protection duration despite reduced thickness and weight, as the materials are engineered to maintain structural integrity and insulation effectiveness under extreme thermal and mechanical loading conditions.
Solution Approach 2:
The protective coating incorporates intumescent materials that undergo phase transition when exposed to fire, expanding volumetrically to form a thick, insulating char layer. This phase transition creates an additional thermal barrier on-demand, extending the thermal protection duration beyond what the base thin wall structure could provide alone, while maintaining a lightweight profile during normal conditions.
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 effectively provides extended thermal protection against extreme temperatures, maintaining structural integrity by reducing thermal conductivity and accommodating cable movements, while minimizing weight and wind drag, thus ensuring the structural safety of civil engineering structures during fires.
Implementation Method 1
A cylindrical thermal protection sheath for covering a length of an elongated structural element, characterised by comprising a sandwich-like composite insulation system having a thermal conductivity lower or equal to 0.11 W/m°C at 800°C
Data Source
AI summary
The invention concerns a cylindrical thermal protection sheath for covering a length of an elongated structural element, comprising a sandwich-like composite insulation system which has a thermal conductivity lower or equal to 0.11 W/m.° C. at 800° C. and a thickness lower than 50 millimeters.