FOAMGLAS Insulation Protects Chilled-Water
FOAMGLAS Insulation Protects Chilled-Water
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Michigan's hostile weather environment can cause a number of problems for the
operation of any piping system, but this is true for chilled-water systems in
particular. That is why when Pharmacia & Upjohn, Inc. decided to connect the chilled-water distribution systems of its Portage Michigan chemical and pharmaceutical complexes, it had to find an insulation system that would protect the pipelines on the trestle against very severe elements.
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The engineering staff at Pharmacia & Upjohn chose Foamglas cellular glass insulation, manufactured by Pittsburgh Corning Corporation, to be used on all piping that transports chilled water, brine, steam and condensate.
The company has operated a plant in Portage, Mich., just outside Kalamazoo, since the early 1950's, which produces materials for pharmaceutical products manufactured by Upjohn as well as other drug manufacturers. Two primary operations take place at this plant: pharmaceutical manufacturing and chemical manufacturing.
The pharmaceutical manufacturing plant is a large indoor facility with a 10,000-ton underground chilled-water distribution system. The chemical manufacturing complex includes several buildings and uses a 6,000-ton chilled-water generation system and an underground distribution pipeline network. For both operations, chilled water is used for air-conditioning applications as well as process-cooling applications, which are vital to maintaining efficient and reliable production efforts.
To sustain site growth, the chilled-water capacity of the two manufacturing operations was increased by connecting them into one common district-cooling system. To do this, an existing above-ground trestle located between the two facilities was rebuilt to accommodate additional chilled-water piping.
Connecting the Chilled-Water Systems
Consolidating the chilled-water systems increased efficiency since it was
then possible for all buildings to be connected into one distribution system,
instead of each building having its own smaller system. Additionally,
connecting the two plants using the trestle system allows future buildings to
easily be tied into the system.
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Fig. 2. FOAMGLAS cellular glass insulation was specified for chilled water, steam and other pipelines because it performs well in a variety of weather conditions. |
The pipe trestle supports are elevated between 22 and 30 feet above ground level, allowing cranes and other equipment with high-clearance requirements to pass underneath. This trestle system now carries about 150 different piping systems, including electrical conduits, brine (a mixture of water and methanol), solvents, compressed air, steam, condensate and a number of chemicals.
Since the pipelines on the trestle are exposed to temperatures below 0(F in the winter as well as hot, humid conditions in the summer, specifying a proven insulation system was of the utmost importance. The steam and condensate pipelines were originally insulated with asbestos when the plant was built. To increase thermal performance, these pipelines were later overfitted with Foamglas insulation applied directly over the asbestos.
The efficiency of all outdoor and indoor chilled-water pipelines was maintained using Foamglas insulation. The two-inch thick, two-foot long half-round sections of insulation were butted together and sealed along the butt joints and longitudinal seams with a silicone elastic caulk to form a vapor barrier. The insulated pipes were finished with an aluminum jacket.
Foamglas insulation for indoor chilled water piping was field installed while the outdoor chilled water pipelines were pre-insulated and placed on the trestle in 40- to 60-foot sections to reduce labor and installation costs.
Today, the chilled-water system at the plant features main supply and return lines ranging in diameter from 16 in. to 24 in. and includes a total of 6,000 lineal feet of insulated piping on the trestle alone.
Specifying the Chilled Water Insulation System
for Freezing Winter Temperatures
During the winter months, chilled water, or any other liquid moving through
an outdoor piping system, can easily freeze when temperatures drop to -20(F
or lower. To minimize the potential for freezing, engineers at Pharmacia &
Upjohn said it is important to keep the water moving as much as possible
within the system and to properly insulate the pipelines.
Dan Guldenzoph, senior engineer/utilities engineering at Pharmacia & Upjohn, said his company specified Foamglas insulation for both the indoor and outdoor chilled-water systems because it performs well over a wide variety of temperatures and weather conditions and is impermeable to moisture, providing long-term insulating value.
"Impermeability and freeze protection were big factors in selecting an insulation," Guldenzoph said. "Pharmacia & Upjohn has had a pretty good history with using Foamglas insulation; therefore, our Standards Committee felt comfortable using the product because of its reputation for reliability."
John Rinehart, a trestle specialist at Pharmacia & Upjohn, is responsible for upgrading and maintaining the pipe trestle and its insulation system. He considers impermeability to be the most important characteristic when selecting an insulation.
"When an insulation absorbs moisture, it never has a chance to dry out," said Rinehart. "When that happens, the insulation doesn't do its job, the chilled water stops moving, the pipes freeze and can break. If that happens, we would need to shut the plant down, strip off the wet insulation, thaw and repair the pipe and then re-insulate it."
Even when freezing, the resulting damage and down time aren't the only concerns; moisture absorption is a leading cause of thermal insulation failure. Problems related to moisture absorption can occur just as easily in warm weather.
Protecting the Pipes from Summertime Humidity
According to Mark Wolthuis, Pharmacia & Upjohn construction specialist, the
company has been using Foamglas insulation on a regular basis since 1985
since it will not absorb moisture. He said, Foamglas insulation is great
for chilled-water piping systems because it's impermeable to water and water
vapor. With the correct sealant, the product makes for a vapor-tight system.
"High-humidity conditions cause even more severe problems for insulation. Unless you have a tight vapor barrier, moisture will migrate toward areas of low pressure, [i.e. chilled water piping]. When moisture comes in contact with the cold pipes, it condenses, and the insulation easily becomes saturated. Other insulations allow vapor to just drive right through. Wet insulation causes the system to lose energy and drives up the operating costs because the chillers need to work that much harder to keep the water cool." Wolthuis said that corrosion results when moisture gets into an insulation system. "When you have wet insulation that just lays against the pipes over a period of time, the pipes tend to rust out pretty quickly," he said.
If a permeable insulation absorbs just 4 percent moisture, it may lose 70 percent of its thermal efficiency. Wet insulation tends to act as a thermal conductor rather than an insulator. An insulation that is impermeable to moisture in both liquid and vapor forms will retain its thermal properties and will not promote metal corrosion. This translates into an extended service-life for both the insulation and the piping that it protects.
According to Wolthuis, compressive strength was another important factor in specifying the insulation. "Most insulation systems need a vapor retarder, which often become damaged because someone walks on, or bumps into the insulation and breaks the vapor barrier," he said. "Foamglas insulation not only acts as a vapor retarder, but its high compressive strength protects it from daily physical damage. Under normal conditions, the product holds up very well to everyday abuses."
While chilled water was the major focus of this project, Wolthuis said he likes the fact that the insulation product meets the needs of a variety of applications. "We have systems that run from -30(F to more than 350(F, and Foamglas insulation insulates just as well at both ends of the range," he said.
According to Rinehart, the insulation system has been performing well. He said, "The Foamglas insulation seems to be in good shape and has been holding up very well since it was first installed. From the looks of things, this insulation system is going to last a long, long time."
Pharmacia AB of Sweden and The Upjohn Company, Kalamazoo, Mich., merged in November 1995 to form Pharmacia & Upjohn, Inc., which is now the world's ninth-largest pharmaceutical company. The new company has 34,200 employees, a research and development budget of $1.1 billion and sales of $7 billion each year.
For more information: Pittsburgh Corning Corporation, 800 Presque Isle Drive, Pittsburgh, PA 15239, (412) 327-6100.
Edited by Larissa Tis