Hot or cold: pipefitters and refrigeration mechanics find solutions.

And shifting from hot to cold was exactly the strategy, too, in a project at CERL, the Construction Engineering Research Laboratory. This collection of facilities is where the US Army Corps of Engineers conduct operations for the Department of Defense (DoD). CERL is described as the “premier center for developing technologies that provide high-quality facilities and realistic training lands to the DoD.”

The buildings are owned by the university but F&S pipefitters and refrigeration mechanics worked together to replace lines of hot and cold water with new pre-insulated pipe technology.

By Jim Smith, F&S Refrigeration Mechanics Sub-Foreperson

Being that it is off the main campus, it has its own facilities and operations. This includes a main boiler house that also serves as the chiller plant. The facility pumps heating and cooling water throughout to maintain operations across their campus.

The boiler house has battled a leak in the underground heating piping for several years. The leak would come and go with seemingly no rhyme or reason. There have been many attempts to find the leak, including pressure testing, ultrasonic testing, and infrared testing. All of which could not pinpoint the leak due to; too small for a pressure drop, too much surrounding noise, and the ground giving off too much heat. Eventually, maintenance noticed a sidewalk starting to settle in an odd location. It was decided to do an exploratory dig to see if that was the location of the leak. After a forty-foot by forty-foot hole was opened up, a leak was discovered. A metal support had been welded to the pipes and the welds had begun rusting away. The crack would open and close with the changes of heat in the pipe and heat in the ground, making it appear to go away and come back.

Now that the leak was found, the question became, “how to fix or should it be replaced?” The heating lines from the boiler house to the main building were 6″ steel pipe and travel ~275 feet, a supply pipe and a return pipe. The chilled water runs alongside the heating lines and is also 6″ steel pipe, supply and return. It was eventually determined to replace all 4 lines and eliminate ever having this problem in the future. This would require in-depth planning. Heating water can be turned off for the summer without much inconvenience. To have chilled water off in the middle of summer would be impossible, as it is what cools buildings on hot days. It would not be feasible to wait until winter to do the chilled water, the trench would collapse before the work could be completed, so they did the work in the summer.

It was decided to rebuild the bypasses on both ends of the underground piping. This would allow the heating lines to be isolated and replaced. Once they were completed, the chilled water could be diverted into the heating lines. This would allow the facility to maintain air conditioning in the hottest part of the summer. With the chilled water running in the heating lines, this would allow for the underground chilled water piping to be replaced. 

A specialty pipe was chosen for the project. It was actually invented for a project on the Urbana campus several years prior. It is an advanced thermoplastic material that has high strength and chemical resistance. An excellent product for buried water lines that comes with a 55-year warranty when installed by properly trained workers. The pipe has a secondary layer that is pre-insulated during the manufacturing process to eliminate the need to be insulated after installation. This results in less labor hours and a better-quality installation. The pipe is heat fused together during installation. This provides a seal from one pipe to the next that is actually stronger than the pipe itself. 

F&S Refrigeration Mechanics and Pipefitters shops were called to see if it was a job we could assist with. It was determined that the Refrigeration shop was able to do the work and the Pipefitters shop would assist as needed. We were able to adjust our work load to be able to spend as much time at once to this project. The workers went through the certification process and were able to receive the full warranty for the piping. Having this certification will also allow us to perform this work in the future on any similar projects on campus.

This was a pretty big project for F&S to be able to complete in-house. It was beneficial to the customer as well. They were able to save a considerable amount by not having an outside contractor come in to do the work.

There are many spokes to this wheel and we are just a part of it.