In a critical environmental protection project in Oregon, Huntingdon Fusion Techniques HFT®'s USA Partner I successfully employed liquid nitrogen freezing technology to solve a significant challenge. The project involved creating new access to the Willamette River to support a salmon hatchery, but a 10-inch pipeline filled with potentially contaminated water obstructed the proposed access route. Cutting the pipeline without precautions would have risked releasing the polluted water into a sensitive and environmentally protected area.
To address this, the team used the Accu-Freeze™ System to create ice plugs within the pipeline, effectively isolating the section that needed removal. This approach allowed the pipe to be safely cut, containing the contaminated water and preventing environmental damage. The project was completed under challenging conditions, including high temperatures, demonstrating the system's reliability and robustness.
This case study highlights the effectiveness of liquid nitrogen freezing as a method for isolating sections of pipework during maintenance, repair, or environmental protection projects. The technology is crucial for preventing environmental contamination and offers a safe and efficient solution for various industrial applications, including nuclear facilities and even space exploration.
Key products like the Accu-Freeze™ System ensure controlled and efficient operations, providing a reliable alternative to draining entire systems. Thus, this technology minimizes environmental risks and avoids production disruptions. It has proven its value in diverse and critical situations, from environmental conservation to space missions.
The Challenge
In a recent project, Huntingdon Fusion Techniques HFT®’s USA Partner played a critical role in solving a significant environmental challenge in a remote area of Oregon. The project was part of an effort to replenish a salmon hatchery, which required constructing new access to the Willamette River. However, a 10-inch (254 mm) pipeline obstructed the proposed access, presenting a dilemma. The pipeline, previously isolated and abandoned, was filled with over 1 million 300 thousand gallons (5,000 m³) of water, which had likely become contaminated. Cutting the pipeline without precautions would have released this polluted water into a sensitive, environmentally protected area.
Faced with the potential environmental disaster of releasing contaminated water into protected land, the decision was made to use liquid nitrogen to create ice plugs in the pipeline. This approach would isolate the small section of the pipe causing the obstruction, allowing it to be safely cut while limiting the release of contaminated water. The released contaminated water could then be contained and removed from the site, minimising environmental impact.
The Process
Pits were excavated on either side of the pipeline to expose the section needing removal. After the anti-corrosion coating was stripped from the pipe, the freezing operation began using the Accu-Freeze™ System. This system creates an in-line ice plug capable of withstanding pressures up to 140 bar in pipes up to 12 inches (305 mm) in diameter. With available modifications, the system can also be adapted to handle larger diameters.
A specially designed insulated aluminium jacket was placed around the section of the pipe to be frozen. An advanced temperature-monitoring unit controlled the pipe's surface wall temperature to accurately and safely create a short ice plug that did not extend outside the jacket. The freezing operation took place under challenging conditions, including record-high temperatures and minimal shade, demonstrating the robustness and reliability of the Accu-Freeze™ System.
Once the ice plugs were securely in place, the pipe was cut on both sides of the obstruction. The remaining contaminated water was drained into disposal containers for removal, and welders quickly capped the open ends of the pipe. The freeze equipment was then shut down, and the ice plugs were allowed to thaw naturally. The project was completed successfully, allowing the river access refurbishment to proceed as planned, thus restoring a vital natural habitat.
Applications and Benefits of Liquid Nitrogen Freezing
The Accu-Freeze™ System is automatic and can be remotely operated, making it particularly useful for applications where engineer access is restricted, such as in nuclear facilities. Liquid nitrogen freezing is effective down to -184ºF (-120ºC), making it suitable for isolating sections of pipe-carrying petrochemicals. This allows for the maintenance or replacement of valves and other control devices without the expense and delays associated with draining the system.
Using liquid nitrogen for pipe isolation has proven effective in various critical applications, including resolving issues with NASA’s space shuttle Atlantis. During mission ST-101, a fault in the hydraulic power drive unit (PDU) was detected just before launch. The PDU controls the shuttle’s rear rudder, and its failure during flight could have been catastrophic. Using liquid nitrogen to freeze the hydraulic lines, engineers could isolate the faulty PDU, remove and replace it, and avoid a costly delay in the launch schedule.
Conclusion
Liquid nitrogen pipe freezing technology provides a reliable solution for isolating sections of pipework during maintenance, repair, or replacement of valves, couplings, and instrumentation. This technology eliminates the need to drain entire systems, thus avoiding production disruptions and reducing environmental risks. Using systems like Accu-Freeze™ ensures safe, controlled, and efficient operations, making it a valuable tool in various industrial applications, from environmental conservation projects to space exploration.
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