For Pre-Stressed Concrete Cylinder Pipes (PCCP), ensuring structural integrity is crucial, and one of the critical concerns is the loss of preload in these pipelines. This loss can result from various factors, including hydrogen embrittlement cracking or corrosion of the reinforcing wires. Non-destructive testing (NDT) tools play a crucial role in addressing these issues. Below, we’ll explore two essential inspection techniques PICA uses: Near Field Testing (NFT) and Remote Field Testing (RFT). Continue reading to learn more about how this innovative technology grants you a clear picture of the condition of your pipelines.
The Importance of Preload in PCCP
Loss of preload in Pre-Stressed Concrete Cylinder Pipes (PCCP) is a serious issue that can lead to pipeline failure. Preload, which represents the tension in the pre-stress wires, can be lost when wires break due to corrosion and hydrogen embrittlement cracking. When the preload weakens, the risk of pipeline failure significantly increases.
Near Field Testing (NFT) Tools
PICA’s NFT tools are designed to detect and quantify broken wires within embedded cylinder PCCP. The technique relies on “transformer coupling” to induce an electric current in the wires, which is interrupted if the lines are broken. PICA’s NFT tools are particularly advanced, featuring several elements that set them apart from competitors.
One notable feature is the use of multiple frequencies simultaneously during electromagnetic (EM) inspections. Additionally, our tools incorporate several detectors to enhance the resolution and accuracy of wire break data. This results in high-confidence inspection results for our clients.
Applications and Limitations of NFT Tools
PICA‘s NFT tools are suitable for dewatered pipeline applications with a minimum 20-inch diameter manway access. They work best for embedded cylinder PCCP with steel cylinder thickness less than 0.25 inches. For PCCP with thicker steel cylinders and lined cylinder PCCP, another tool, Remote Field Testing (RFT), is employed to assess the condition of the steel cylinder and identify local changes in stress. This proactive approach can help identify areas of concern before the first wire break occurs.
The large-diameter NFT tools, suitable for pipelines ranging from 48 to 120 inches, offer several capabilities:
- Live data streaming.
- Can be equipped with high-resolution CCTV and LiDAR.
- Sensitive down to detecting as few as five continuous wire breaks.
- Modular components can be assembled inside the pipe.
- Electric drive wheel to convey the NFT through the pipe at approximately 45 feet per minute.
Remote Field Testing (RFT) Tools
While NFT tools are primarily designed for PCCP inspections, PICA’s RFT tools, like the EMIT Inspection Tool and SeeSnake Inspection Tools, can assess the condition of various pipelines in far greater detail. These tools are invaluable for inspecting a wide range of pipelines and identifying seam weld defects, wall thickness variations, preload loss, cracks and more. By proactively inspecting water pipelines, PICA’s team ensures you have a clear image of the condition of your pipelines, thus enabling you to make an informed decision regarding repairs and replacements.
Your Source for RFT and NFT Pipeline Inspections
PICA utilizes a comprehensive range of inspection tools designed to address pipeline maintenance and integrity assessment needs. Our NFT tools excel at detecting wire breaks in embedded cylinder PCCP, while our RFT tools serve a broader spectrum of applications. PICA’s NFT and RFT tools play a pivotal role in the maintenance of critical infrastructure, ultimately ensuring the continued and uninterrupted flow of vital resources.
Contact PICA today to learn more about our pipeline inspection services and how we use these innovative, non-destructive technologies.