Freezing the Lines
A cost-effective alternative to draining and refilling pipes
A refrigeration contractor needed to install isolation valves on two 24-inch pipes servicing the 5-building government office complex in Columbia S.C. The overall project required tying a new piping system in to an old existing line. Draining the system posed too much risk of allowing air into the system, causing possible equipment failure and loss of costly treatments. Freeze Service, Inc., was called in to isolate the lines for valve installation.
The 24-inch supply and return lines fed numerous branch lines to the government buildings' chilled water supplies, including air handling units. Shutting off the water supply, draining the pipes and refilling the lines was not an option for the refrigeration company since doing so would cause severe work delays and equipment problems. Freeze plugging the pipes would take less than half the time of cutting and draining, and that's the direction the refrigeration company chose to go.
Work started on Friday afternoon with the 24-inch pipes, one freeze on the supply line and one on the return. Using liquid nitrogen, Freeze Service isolated the problem area in the pipe with solid freeze plugs of the water. Freeze Service's patented, highly efficient, pipe freezing equipment was used for this project. This meant less liquid nitrogen than other pipe freezing services use. Approximately half of a 6,000-gallon tanker was used on this project, compared to a full tanker used on other job sites.
After the first two freeze plugs were established and isolation valves were installed, workers moved farther downstream where one 18-inch and three 6-inch freezes were required for additional valves to be installed.
With these isolation valves in place, the mechanical contractor could finish tying in the new system with no time spent draining or refilling the pipe, no loss of water to building cooling/HVAC systems, and no equipment problems. Once the work was completed, the plugs were allowed to thaw naturally and the line was back in operation.
By early Sunday morning, approximately 30 hours after starting, all work was completed, and Freeze Service and its equipment were off the work site. Originally, work was scheduled to be completed Monday.
One challenge the Freeze Service crew faced in South Carolina was being in an underground tunnel beneath Columbia's city streets to work on the pipes. This confined work environment required a ventilation system to continuously supply the tunnel with fresh air.
Since the pipes weren't drained and refilled, there was less chance air could get into the lines. With several miles of underground piping, the refrigeration company had the potential for major problems. As people in the industry know, air in the system means potential for internal residue on the pipes to loosen, thus damaging or plugging equipment ? a much more costly and time-consuming dilemma to fix.
The Columbia, S.C., project is just one example of Freeze Service's pipe freezing capabilities. There are a variety of other applications. Please visit our website for more information about freeze plugging.
