Splash Zone Protection Stands Test of Time
Case study shows technology performs in GOM environment -
John Miley, Stingray Pipe Co.
Co. has identified a field applied, composite encapsulation system that can
withstand the environmental stresses placed on risers in the splash-zone of
offshore drilling and production rigs. The company began looking for such a
system over five years ago after one corrosion protection system, installed on
several risers at the platform at West Cameron 509 A, failed and had to be
removed before anything new could be applied. (Offshore - April 1995)
Stingray needed a long-term, cost-effective, corrosion protection
system that could be field applied in the splash zone. Many operators in the
Gulf of Mexico have experience with field-applied coatings and wrap systems.
Stingray had tried several, but none provided the long-term protection needed.
Stingray learned the A-P-E Process field applied encapsulation system
had been used for several years as corrosion protection on coastal structures,
but had not yet been used offshore. While this system, manufactured by Master
Builders, Inc. of Cleveland, Ohio, had an excellent track record onshore,
Stingray was not sure it would perform as well on a platform 98 miles offshore
in the Gulf of Mexico.
Severe wave action at the West Cameron 509 A site had contributed to
the failure of an earlier system and would present a challenge to any new
system the company planned to apply. Key benefits to the new system, according
to Stingray, were that it properly addressed the problems of installation and
long-term durability in wave active environments. After completing an
evaluation, Stingray engaged MADCON Corp., of New Orleans, to install A-P-E
Process encapsulations on several risers at the West Cameron platform. This
represented the systems first application in the Gulf of Mexico.
|The tops of encapsulations on two suction risers seen a year after installation (left) and 4 1/2 years after installation (right).
The A-P-E Process consists of a translucent Fiberglass Reinforced
Plastic (FRP) outer jacket and aggregate filled epoxy grout. The jacket and
grout bond tightly with the encapsulated member to form a composite. One of the
advantages of the A-P-E Process is that it can be installed in several steps.
After surface preparation, the outer FRP jacket is placed around the riser and
sealed. Once the jacket is securely in place, the aggregate filled epoxy grout
is pumped into the jacket from the bottom up. During this separate operation,
the progression of grout is monitored through the translucent jacket. This
monitoring procedure helps ensure a complete, void-free encapsulation. The
separate pumping step also creates a mechanical scouring effect when the aggregate
filled grout is forced upward within the confines of the jacket. This scouring
effect makes a significant contribution to achieving the final bond between the
encapsulation materials and the riser. Aggregate filled epoxy grout, as opposed
to neat epoxy, is thermally compatible with the steel riser. This compatability
minimized the risk of delamination. Installation in separate, manageable steps
also allows the installation contractor to work more effectively in the
wave-active splash zone.
Stingray has continuously monitored the condition of the encapsulations
since the installation of this system, in 1994. The monitoring consisted of
periodic visual examinations, combined with 'sounding.' Sounding involves
striking the encapsulations with a hammer or other object to detect any change
in sound that might indicate delamination within the encapsulations or
disbondment from the risers. In addition, the encapsulations have been
physically tested for bond to the risers by the Modified Elecometer test
method. This test employs a hand-held device that applies a direct tensile load
to a test dolly adhered to the outer surface of the encapsulation. Coring
through the encapsulation, down to the riser surface isolated a 3-in. Diameter
section of the encapsulation. This test is considered an effective means of
evaluating corrosion protection systems because it determines the actual bond
oat the interface between the encapsulation materials and the riser.
This procedure also produces a sample of the encapsulation materials
that can be examined for signs of delamination or products of corrosion. A
typical 3-in. Diameter sample, called a `divot,' is seen with the test dolly
attached. At maximum test load, the aggregate filled epoxy grout typically
fails adjacent to the riser interface, leaving some of the grout still adhered
to the riser. When the test is complete, the test dolly is removed. The divot
is coated with epoxy paste and placed back into the cored test hole to re-seal
the encapsulation. The most recent series of tests, performed in late 1998 at
West Cameron 509 A, indicated that the encapsulations, which were by this time
more than four years old, remained tightly bonded to the risers. No signs of
corrosion were found.
The encapsulations are currently in their fifth year of service, still
protecting the risers in the severe environment found 100 miles offshore. There
is no evidence of deterioration and, aside from a slight build-up of marine
growth, the encapsulations appear as they did when first installed. They have
been carefully examined for signs of delamination or disbondment, including the
possibility of cathodic disbondment, and none has been found.
the June 1999 Edition of Offshore
Splash Zone Corrosion is a
serious and costly problem.
The Solution: MADCON and
the A-P-E© Process!
Master Builders' A-P-E© Process... a laboratory tested, field proven,
all-polymer composite for long lasting, cost-effective splash zone protection.
Since 1983, the
A-P-E Process has been specified by owners and operators of marine structures,
including major oil companies, U.S. government agencies, State and Municipal
Departments of Transportation and Port Authorities. There are now more than
1,000 installations which are over ten years old.
Madcon Corporation - Master Contractor of A-P-E Process
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