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Background
- A 650 ton refrigeration machine for a New York City property, which had shown
up to an 85% loss of tube wall thickness for some copper tubes in the
evaporator or chiller section, was in need of re-tubing at a proposed cost of
$90,000. Instead, a coating of Teflon was applied on-site using the latest
patented application methods.
Each tube
was sandblasted with specially developed equipment in order to bring the
surface to an SP-5 bare white metal finish - while at the same time removing a
minimum of material. Then, the front and back heads, waterboxes and partitions
were similarly cleaned of all paint and deposits down to bare white metal. All
dust was removed and the surfaces cleaned.
The tubes, heads
and waterboxes were then bonded with two high pressure coating applications of
approximately 3 mils each of an epoxy Teflon ®
polymer - thereby eliminating any further wear, abrasion,
corrosion, or biological buildup on the copper tubes. A heavier final coating
was applied to the heads, waterboxes, and partitions
only.
The turnaround was one week and the
chiller was returned to service 24 hours after the final coating had been
applied. A before and after comparison of inlet and outlet water temperatures
by engineering staff showed no detectable loss of heat transfer.
The net result -
A cost savings of nearly 75% over conventional re-tubing, a chiller which will
never foul from either microbiological or particulate attachment, and which
will require little if any tube cleaning. Further eddy current testing is
eliminated since the copper tubes are now completely isolated from water
contact, and therefore any possible corrosion induced metal
loss.
This process is ideally suited for
refrigeration chillers, especially on the more corrosion susceptible condenser
water side, and is the ultimate corrosion solution for those facilities with
chillers having enhanced tubes - such rifled tubes having proven to be highly
susceptible to fouling and biological attack within their internal grooves.
This process is also well suited to house tanks, fire storage tanks, tube and
shell heat exchanges, as well as cooling tower basins and relatively straight
runs of piping.
The following
represent a series of photographs taken from the above referenced chiller
project, along various stages of completion.
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Overall, tube
coating offers substantial benefits as a cost savings measure against
re-tubing, and as a means to increase building efficiency and lower operating
costs. Please contact CorrView International, LLC for further information.
©
Copyright
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