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THE CHALLENGE: A 24” steel fuel oil pipeline buried in
a tidal shrimp producing area had developed leaks in some of its welded joints.
The pipeline was encased in a 3” thick concrete weight coat which had to be
removed at each joint to allow inspection and repairs. Inspection, remediation
and recoating had to be undertaken within short intervals at low tide, immersion
of the repaired areas before curing was inevitable as the next tide came in. A
completely “field-friendly” coating that could withstand immersion in salt water
shortly after application was required to allow the work to be performed.
THE SOLUTION: TFT Kevlar® reinforced BIO-DUR 561 epoxy
coating was chosen for this project. This product is specifically designed for
wet surface and underwater application to steel in either salt or fresh water.
BIO-DUR 561 is a 1/1
volume mix product; this is the ideal mix ratio from a practical point
of view since minor mixing errors in mixing have the minimum effect on
performance. The components were supplied in contrasting colors of Red
Oxide epoxy base and White curing agent to yield a uniform Red mixture.
The steel surfaces were
prepared for coating by high pressure water blasting with entrained sand
abrasive. The blasting equipment used consisted of an 18HP water jet producing
about 4,000 psi through a hand held nozzle equipped with a venturi type abrasive
delivery system mounted at the gun. This simple equipment easily removed an
existing coal tar based anticorrosive coating to yield a “white metal” surface.
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The freshly blasted surface was rinsed with clean fresh water to remove sand
and debris then immediately coated while still wet using BIO-DUR 561 applied by
brush and pads.
Work proceeded along the length of pipe in excavations 40’ apart. Because of
the dangerous mobile nature of the tidal flats it was necessary to stabilize the
holes using trench supports, even so the work area around the pipe was a
challenging quicksand which quickly engulfed the freshly coated pipe once pumps
were removed.
THE RESULT: Application by brush and pressure pad was effective and
yielded an excellent, tightly adherent film. The BIO-DUR 561 applications cured
well overnight and formed a tough, tightly adherent protective coating over the
pipeline. The freshly applied coating was resistant to removal by wave action
from the moment of application and suffered no damage before curing hard.
For more information regarding this project contact:
Jeff Longmore, Technical Director
Thin Film Technology, Inc.
P.O. Box 580669
Houston TX 77258-0669
(713) 910-6200
FAX: (713) 910-6210
E-mail: jeff@thinfilmtech.net
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