SilcoTek Coatings - Overview - page 67

SilcoNert 2000 is aproprietary (U.S. Patent #6,444,326), silicon, chemical
vapor-deposited (CVD) coating, specifically designed to improve the sulfur
inertness and chemical inertness of steel, stainless steel, alloys, glass, and
ceramics. The unique non line-of-siteCVDprocess produces a flexible,
high temperature capable, amorphous silicon layer that diffuses into the
metal lattice. The coatingwill conform to themost intricate surfaceswhile
maintaining highdimensional tolerances. SilcoNert 2000will deformwith
tubing surfaces allowing for radius bends andwill not interferewith
threadedor compression joints;makingSilcoNert 2000 the ideal coating
for process sampling, refinery gas sampling, anddownhole sampling
applications.
SilcoNert 2000 is an inert, chemically protectivebarrier of amorphous silicon
material inter-diffusedwith the host substrate resulting in a
100-250 nm coating. The surface is further passivatedwith
covalently bondedhydrocarbonmolecules (as described in
USPatent #6,444,326) as verifiedby an average surface contact
angle value greater than 75° usingdeionizedwater on aprocess control
couponor GC inlet liner.
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Figures2and3compare the sulfur transport propertiesof 100 foot (30.5
meter) lengthsof SilcoNert 2000 treated, electropolished, and raw
commercial grade 1/8inODx0.020”wall stainless steel tubing.
Figure2demonstratesuptakeof 500ppmv
methylmercaptan sulfur compoundby the3 tube
surfaces.
TheSilcoNert2000 treatedelectropolished
tubingdidnot adsorb themethylmercaptan
toanymeasurableextent, deliveringa
representative samplewithnodelay. The
untreatedelectropolished tubing totallyadsorbed
methylmercaptan formore than75minutes, the
sulfur gas level didnot stabilizeuntil 130minutes.
Conventional 316L seamless tubing totally
adsorbedmethylmercaptan formore than90
minutes; the sulfur gas level didnot stabilizeuntil
140minutes.
Figure2: SilcoNert2000 treated tubingdoes not
adsorbmethylmercaptan (500ppbv) compared to
electropolishedand standard stainless steel tubing.
(Datacourtesyof Shell Corp. andO’BrienCorp.)2
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When adsorptionof sulfur-containing compounds
is prolonged, desorption from the surface can
slowly causedisruptive false readings in
process, refining anddown-hole sampling
applications. This “memory” of adsorbed
sulfur compounds can cause longdelays
in equilibrating a sample stream. Figure
3demonstrates thememory effectsof
the three typesof tubingused to transfer
streams containing sulfur compounds. The
SilcoNert 2000 treated tubing shows less
retentionof sulfur compoundsby several
ordersofmagnitude, indicating very high sulfur
inertness. SilcoNert 2000 treated sample
pathways caneliminatecostly refinery product
lossesdue to falseor delayed readings.
Figure 3: SilcoNert 2000 treated electropolished tubing shows nomemory
effects. Sulfurmemory is prolonged in raw commercial grade stainless steel
tubing. (500ppmvmethyl mercaptan inhelium). (Data courtesy of Shell Corp.
andO’BrienCorp.)2
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