Chemical Engineering December 2011 - 49

2011 revision
3/08/11 - 4:46 PM
FIGURE 5. Steel bolted tanks with epoxy
coatings are commonly used as holding
tanks for process water at chemical processing
facilities
when properly designed, will allow for
adding rings (think upward) without
affecting the coating on the original
tank. A tank with a field-applied coating
would require complete recoating
after the expansion is completed.
'Green' tank coatings
The process of applying coatings after
construction to field-welded and concrete
tanks may also present challenges
to the environment. Tanks
constructed in the field must undergo
sandblasting to prepare the surface.
The field application of coatings includes
the possibility of overspray and
the release of volatile organic compounds
(VOCs) into the environment.
Safety measures must be taken to capture
the VOCs. Bolted panel (Figure 5)
and factory welded tanks that receive
their coatings at the factory present
less challenge to the environment because
sandblasting particles and coating
overspray are captured in highly
efficient particle filtration systems.
Bolted tanks generally require less
space in the field to construct. Onsite
welding and concrete construction require
a significant footprint in order
to stage materials and construct the
tank. This will require destruction of
trees and local habitat that cannot
be easily replaced after completion.
Bolted steel tanks have been constructed
in certain sites with as little
as 5 ft of buffer between the tank and
the environment around them.
Inspection and maintenance
Once a year, tanks should be inspected
both inside and out to make sure
they are in good shape. Any corroded
areas should be properly prepared
and touched up with a suitable maintenance
coating. All sealants should
be reviewed and reapplied wherever
needed. One common rule of thumb is
that a tank should be considered for
repainting when it shows rust on 1%
of its surface. A tank that is neglected
will be susceptible to product contamination,
extensive maintenance and recoating,
safety hazards and significant
Locating an experienced vendor
To ensure the best quality coating on
your tank, ask tank vendors to provide
testing data and case histories
about durability and how the coating
performed against corrosion and
abrasion with a product like the one
to be stored. Ask how long the company
has been fabricating tanks,
what type of coating it uses, whether
its coatings are factory applied and
thermally cured (or field applied and
cured by ambient air), what are the
quality control measures, what is the
volume sold, in what countries, and
into which markets. Also consider
tank manufacturers with third party
accreditation, such as the ISO Quality
Certification.
■
Edited by Gerald Ondrey
Author
David Wheat is director of
inside sales at CST Storage,
a division of CST Industries
(2101 South 21st Street,
Parsons, Kan. 67357; Email:
dwheat@cst-storage.com),
a
company that specializes in
the design, fabrication, factory
coating and construction
of tanks and covers for dry
bulk and liquid storage applications.
He holds a B.S.E.E.
from Yale University (New Haven, Conn.) and
has more than 18 years of experience in liquid
and dry bulk storage.
Tony Thill is vice president
of CST Industries, Inc. (9701
Renner Blvd., Lenexa, Kan.
66219;
Email:
tthill@tanks.
com), a global leader in providing
complete storage and
cover solutions for all types of
applications. Thill has more
than 25 years of experience in
growing businesses and product
lines for many different industries
and applications. He
leads efforts in new market and product development,
distribution development, international expansion,
acquisitions and joint ventures and go-to
market strategies for all CST divisions. Prior to
CST, Thill spent the bulk of his career with GE
Energy's Environmental services division eventually
leading the Dry Filtration business segment
formerly known as BHA Group, Inc. Thill holds a
B.S. from The University of Kansas.
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CHEMICAL ENGINEERING WWW.CHE.COM DECEMBER 2011 49
downtime. Contact the tank manufacturer
for recommendations, and make
sure that the chosen maintenance
coating is compatible with the stored
product and environment.
Corrosion significantly shortens the
life of a tank, so a good quality coating
and application process during the
manufacturing process often means
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the need to recoat the tank.
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Chemical Engineering December 2011

Table of Contents for the Digital Edition of Chemical Engineering December 2011
