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Publisher Offshore Technology Conference Language English
Document
ID 3020-MS
DOI
10.4043/3020-MS
Content
Type Conference Paper
Title PROTECTIVE COATINGS AND ANTIFOULING PAINT THAT CAN BE
APPLIED UNDERWATER
Authors Richard W. Drisko, Civil Engineering laboratory
Source Offshore Technology Conference, 2-5 May , Houston,
Texas
ISBN 978-1-55563-570-1
Copyright 1977. Offshore Technology Conference
Preview ABSTRACT
Protective coatings and antifouling paints have been developed
that can be applied by brush, roller, or plastic applicator to
underwater surfaces. Field studies to date indicate that steel
surfaces can be protected from corrosion and marine foulingusing
these products for at least 1 years. Field testing to determine
surface preparation requirements for underwater
coating showed that surface preparation by abrasive blasting is
best, but that power wirebrushing or water blasting may
provide satisfactory surfaces for coating underwater. All of the
formulations containing organ biocides displayed some
degree of resistance to marine fouling and those with 6-percent
tin compared quite favorably with the standard Navy
copper-based antifouling paint used for comparison purposes. The
new formulations can be used to repair damaged
coatings or restore fouling resistance on waterfront and
offshore structures and on hulls of ships without their removal
or
dry docking, thus resulting in considerable savings in time or
money.
INTRODUCTION
A simple method of applying durable protective coatings and long
lasting antifouling paints to structures located
underwater has been a long desired capability. It would permit
repair of damaged or weathered coatings on fixed orfloating
structures without their removal from the water. It also would
permit touch-up or renewal of hull coatings without
drydocking of vessels and coating of keel block areas
inaccessible during drydocking. This paper describes work
conducted by the Civil Engineering Laboratory toward reaching
this goal.
BACKGROUND
The first type of underwater-applicable coatings produced
commercially were the high viscosity , epoxy-polyamide
formulations1-4
commonly called "splash-zone compounds." These products are
based on a formulation of Shell Chemical
Co.1,2
The two differently colored components are thoroughly mixed
before application at a thickness of 1/8 to in to damp
or submerged surfaces. This is done most commonly by pressing
with the palm of the hand or a glove against the
substrate, but a fiberglass, burlap, or canvas backing can be
used. Curing ordinarily occurs to a significant extent at
temperatures above 60F (16C). The mixed resin is slightly
soluble in water so that splash-zone compounds can beworked to give
a smooth finish. This solubility also permits cleaning of equipment
with water before curing occurs. The
Navy has prepared a specification, MIL-P-28579(YD), on
splash-zone compounds. It has been shown that a sandblasted
surface was best for bonding of splashzone compounds to steel,
but wirebrushing or cleaning with a needle gun may
provide an adequate surface.
More recently, several underwater brushable coatings have been
developed, and marketed. Most of them are solvent -free
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