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www.restek.com2005 vol. 3
Introduction
Often, gas transfer systems require low moisture content, low moisture 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 periodic maintenance, prolonging equilibration times, and allowing sys-
tem contamination and inaccurate analytical results. In contrast, 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 in Restek treated substrates.¹ Wet-up curves for Siltek®
Superior Moisture Dry-Down and Corrosion Resistance
Restek treated tubing and system components improve
analytical reliability and prolong lifetimes.
By Gary Barone, Restek Performance Coatings Division Manager, David Smith, RPC Chief Scientist, and Martin Higgins, RPC Chief Engineer
• Up to three times faster response to moisture changes in process streams.
• Corrosion resistance improved tenfold, or more—prolongs component lifetime and maintains pure product stream.
• Custom services: can be applied to existing equipment.
Figure 1
Restek treated electropolished tubing stabilizes at 1ppm
moisture much faster than conventional surfaces.
1
Figure 2
Restek treated electropolished tubing dries much faster
than conventional surfaces.
1
Table I
Restek treated electropolished
tubing provides 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 10 microns.
The amorphous silicon layer can be further functionalized using
the patented Siltek
®
process (US Patent #6,444,326), which
reduces moisture hold-up and improves surface inertness.