Pre-Stressed Concrete Pipe Without Corrosion-Prone Wires
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Solution Overview
Problem
Pre-stressed Concrete Cylinder Pipes (PCCP) face issues with hydrogen embrittlement and corrosion of high-tension wires, leading to potential pipeline shutdowns due to wire breakage, and existing concrete pipes lack the strength and durability to withstand water pressures and soil loads effectively.
Innovation Solution
A pre-stressed concrete pipe design featuring a metallic outer casing and a cast concrete tube with a pressurized solidifying compound, such as epoxy resin, between the metallic cylinder and the concrete tube, which maintains the concrete in compression, utilizing the maximum allowable stresses of both steel and concrete, and includes a bell clamp for secure pipe joints to prevent leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-tension wires are used to pre-stress the concrete pipe, then the pipe can withstand water pressures and soil loads, but the wires are prone to hydrogen embrittlement and corrosion leading to wire breakage
Solution Approach 1:
The patent removes the high-tension wire pre-stressing mechanism from the PCCP design. Instead of using wires that wrap around the concrete core, the invention uses a steel cylinder that is directly cast against the concrete tube, eliminating the need for separate pre-stressing wires and their associated corrosion protection systems.
Solution Approach 2:
The patent merges the pre-stressing function with the structural cylinder. The steel cylinder serves both as the pre-stressing element and as the protective outer casing, combining multiple functions into a single integrated component that eliminates the need for separate wire systems.
2Reliability
If cathodic protection and periodic inspection are implemented for PCCP, then wire corrosion is reduced, but the complexity and cost of maintenance increase
Solution Approach 1:
The patent eliminates the need for cathodic protection systems and periodic inspection requirements by removing the vulnerable wire components entirely. The design achieves corrosion protection through the inherent integrity of the cast steel cylinder and concrete tube interface, without requiring additional protection systems.
3Strength
If a single concrete core is used instead of two concrete cores separated by steel cylinder wall, then the pipe can utilize maximum allowable stresses of both steel and concrete simultaneously, but the manufacturing precision requirements increase
Solution Approach 1:
The patent combines the steel cylinder and concrete tube into a single integrated casting operation. The steel cylinder is positioned within the concrete tube during the concrete pouring process, ensuring precise alignment and intimate contact between the two materials, which eliminates the need for separate pre-stressing operations and reduces manufacturing complexity.
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 design significantly increases the pipe's line-load capacity, enhances strength and rigidity, reduces the risk of corrosion, and ensures reliable sealing at pipe joints, outlasting traditional pipes and minimizing the need for costly rehabilitation.
Implementation Method 1
injecting solidifying compound such as epoxy resin under pressure between them putting the concrete pipe in compression
Implementation Method 2
After the compound is solidified, the concrete pipe will remain in compression
Implementation Method 3
the epoxy's bonding also makes the steel cylinder and concrete pipe to become a more desired integral pipe
Implementation Method 4
the entire concrete wall and the layer of epoxy resin protect the steel wall from corrosion
Data Source
AI summary
A pre-stressed concrete pipe is made by casting a concrete pipe inside a metal cylinder and then being pre-stressed by injecting solidifying compound under pressure into the boundary between the metal cylinder and concrete pipe, and includes a pair of end rings within the metal cylinder, each having a metal ring with an annular groove and an elastic band having a curved end to provide a rounded corner on the concrete pipe. After the solidifying compound is solidified, the concrete pipe retains the compression increasing its strength to withstand pressure, and moments caused by external loads. The pre-stressed concrete pipe further includes a bell ring mounted at one end and a spigot ring having a gasket ring at the other end. A bell clamp is mounted on the bell ring.