Our experienced engineers delivered a specialist pipe freezing and gate valve removal project at Lycée Français Charles de Gaulle School in South Kensington. The client required the removal of a redundant 2½” flanged gate valve on their calorifier pipework. A traditional drain-down of the system approach to replace the valve, would have created unnecessary disruption.
What’s more significantly extended the downtime of their heating and hot water systems. To keep the site operational, our team used liquid nitrogen pipe freezing to isolate the pipework safely, complete the valve removal, and reinstate the system with minimal interruption. Discover the full details about this project below:
Before
Removal of Redundant Gate Valve
The school needed to remove the existing 2½” flanged gate valve without draining the calorifiers or affecting the wider heating system. A drain-down would have impacted staff, students, and onsite operations. Additionally, the site wanted a fast, controlled method that maintained safety standards and avoided the risks associated with refilling and venting large hot water systems. Because of these requirements, pipe freezing offered the most efficient and least disruptive solution.
Ensuring Stable Conditions for Pipe Freezing
To establish a safe pipe freeze, the school isolated the boilers and calorifiers 24 hours before our arrival, which allowed the pipework to cool down to ambient temperature. This step ensured optimal conditions for forming solid ice plugs and prevented temperature-related complications during the freezing process.
After
Once on site, our engineers isolated the water service feeding the calorifiers and secured safe access to the pipework. This preparation allowed us to work efficiently and maintain full control of the system throughout the project.
Pipe Freezing Process
Applying Three Liquid Nitrogen Freezes
We applied three separate pipe freezes to isolate the system safely:
- 2½” calorifier line
- 2″ section
- 2″ open vent
We used professional-grade freeze jackets and liquid nitrogen to form solid ice plugs within each section. Throughout the process, we monitored temperature, freeze progression, and stability. This ensured the pipework remained fully isolated and secure before proceeding with any removal or replacement works.
Valve Removal and Modifications
Replacing and Securing the Pipework
After
After confirming the isolation points held correctly and the system was stable, we carried out the following works:
- Removed the existing 2½” flanged gate valve
- Installed two blanks on the corresponding outlets
- Plugged the open vent to secure the line
This sequence ensured the calorifier pipework remained sealed and structurally sound. The controlled freeze allowed our engineers to complete the replacement work without draining the system or causing disruption to the building.
Thawing, Testing and Final Checks
Ensuring the System Returned to a Safe Condition
Once the new components were installed, we allowed the pipe freezes to thaw naturally. Our engineers monitored the pipework closely throughout the thawing process to confirm the system remained stable. We then:
- Checked all joints and outlets for leaks
- Verified successful isolation of one calorifier, as requested
- Prepared the area for handover for the boilers to be reinstated by others following completion of our works
As part of our commitment to site safety and environmental responsibility, we cleared all redundant components and transported them to a licensed recycling and waste facility.
The school arranged for their team to reinstate the boilers following the completion of our works.
Project Benefits
1. No System Drain-Down
The use of liquid nitrogen pipe freezing eliminated the need to drain large calorifier vessels. This protected the system, saved time, and prevented extended downtime.
2. Reduced Disruption to Operations
Because the school remained operational throughout, teaching schedules, staff routines, and facilities usage continued without interruption.
3. Faster Delivery and Recommissioning
Pipe freezing created a controlled isolation point, which shortened project time and avoided the lengthy process of draining, refilling, reheating, and venting.
4. Lower Risk to the Heating System
Draining large systems can introduce air, corrosion risks, and imbalances. Pipe freezing removed these risks and preserved system integrity.
5. Cost-Effective Method
By eliminating draining and refill labour, pipe freezing delivered a more economical approach for the client.
Why Pipe Freezing Works Well for Calorifier Repairs
Pipe freezing offers a precise method of isolating sections of live pipework while maintaining full operation of the wider system. For schools, hospitals, commercial buildings and industrial facilities, this method supports:
- Minimal downtime
- Lower operational impact
- Controlled working conditions
- Safer valve and fitting replacements
Calorifier systems, in particular, benefit from pipe freezing because they hold large volumes of heated water that would require long drain-down periods. By forming ice plugs at targeted points, engineers work efficiently without affecting the entire heating network.
Frequently Asked Questions
What is Pipe Freezing?
It is a technique that stops pipework water flow to allow for building maintenance works to take place. To learn more about the process, please read our guide.
Can pipe freezing safely isolate larger pipe sizes?
The team freeze steel and copper in sizes ranging from small domestic lines up to commercial diameters of 12 inches, depending on system conditions. For plastic pipework we offer another technique.
How long does each freeze last?
A correctly applied freeze provides several hours of isolation. This window allows engineers to remove valves, install new fittings, or complete modifications without rushing.
Does pipe freezing damage pipework?
We use approved freeze jackets and controlled methods. The ice plug forms internally and expands in a way that protects the pipe wall and does not damage the pipework.
Is pipe freezing more efficient than draining?
In most cases, yes. Draining calorifiers and large heating systems takes considerable time and often results in airlocks. Pipe freezing removes these issues entirely.
Can operations continue during a pipe freeze?
This method isolates only the targeted section, so the wider system continues to function normally.
Speak to IDWe Ltd About Pipe Freezing and Valve Replacement
If your commercial or industrial site requires a valve replacement, calorifier repair, or controlled isolation in South Kensington our pipe freezing services offer a reliable and cost-effective solution.
Do you have Maintenance works planned?
Get in touch today for a quote or expert advice, please call 020 8302 7644 or email info@idwe.co.uk
We can adapt our services to suit your industrial and commercial needs, learn more about our pipe freezing services.
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