•
14
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800-356-1688 •
2005vol. 3
Introduction
Often, gas transfer systems require lowmoisture content, lowmoisture reten-
tion, and high resistance to corrosion. The current substrates of choice,
including electropolished VIM/VAR (vacuum induction melt/vacuum arc
melt) 316L stainless steel, typically are insufficient in these capacities, increas-
ing periodicmaintenance, prolonging equilibration times, and allowing sys-
temcontaminationand inaccurateanalytical results. Incontrast, surface treat-
ments available through the Restek Performance Coatings Group greatly
accelerate wet-up and dry-down times and dramatically improve corrosion
resistance.
Experiments measuring the response time for moisture content change in
Restek treated electropolished stainless steel tubing,untreated electropolished
stainless steel tubing, and standard 316L stainless steel tubing, demonstrate a
significant advantage inRestek treated substrates.¹Wet-up curves for Siltek®
SuperiorMoistureDry-DownandCorrosionResistance
Restek treated tubingand system components improve
analytical reliabilityandprolong lifetimes.
By Gary Barone, Restek Performance Coatings DivisionManager, David Smith, RPC Chief Scientist, andMartinHiggins, RPC Chief Engineer
• Up to three times faster response tomoisture changes inprocess streams.
• Corrosion resistance improved tenfold, ormore—prolongs component lifetimeandmaintainspureproduct stream.
• Custom services: canbeapplied toexistingequipment.
Figure1
Restek treatedelectropolished tubing stabilizes at 1ppm
moisturemuch faster than conventional surfaces.
1
Figure2
Restek treatedelectropolished tubingdriesmuch faster
than conventional surfaces.
1
Table I
Restek treatedelectropolished
tubingprovides the shortest drying times.
1
Time Require
d to
Detect Change (min.)
Moisture
Treated
Untreated
Concentration Electropolished Electropolished Standard
From
To
Tubing
Tubing
Tubing
10ppm* 5ppm 4
5
13
5ppm 1ppm 22
46
71
1ppm 500ppb
40
63
96
500ppb 100ppb
80
103
153
100ppb
50ppb
98
121
—
*Initial moisture concentration.
did
you
know?
Restek surface treatments deposit an amorphous silicon based
layer onto, and into, the steel surface through a chemical vapor
deposition (CVD) process. All exposed surfaces are coated. For
corrosion resistance, layer depth is optimized at 5 to 10microns.
The amorphous silicon layer can be further functionalized using
the patented Siltek
®
process (USPatent#6,444,326), which
reducesmoisture hold-up and improves surface inertness.
