Steve Kirkup, director of submarine materials engineering at General Dynamics Electric Boat, told Seapower
that there are several techniques the company uses to
combat corrosion. He described a three-pronged effort:
the proper selection of materials for the seawater environment, proper corrosion protection via coating systems and the use of “cathodic protection” in areas where
corrosion-resistant material cannot be used. Cathodic
protection is a technique that protects the metal by
making it the cathode of an electrochemical cell, essentially wrapping it in a “sacrificial metal” that corrodes
instead of the protected metal.
“When we design a ship, obviously we’re going to
have materials exposed to seawater and susceptible to
corrosion,” Kirkup said. “NAVSEA and Navy labs all
collaborate on how to design a ship to be protected
from corrosion using those three methods. But cor-
rosion is one of our primary concerns in that it can
increase maintenance periods when a boat comes in for
overhaul. It causes failure of mission equipment, it can
impact the ship at sea and corrosion can at any instant
turn into a very costly repair, so it is imperative that we
protect ships from corrosion.”
When a ship is designed, a corrosion-control plan
is baked in that encompasses those three methods of
protection, from the structure down to the components.
Kirkup said new materials, both metallic and nonmetallic, are showing promise in corrosion control. The
use of composites in ships is growing, replacing the
need for steel plates that have been relied on in the past.
There also is the use of robotic controls to apply coatings in a more consistent manner, resulting in a uniform
surface preparation and application of coatings.
That may sound minor, but it adds up to big savings
over the decades-long lives of the many ships in the
Future technologies that are not quite ready for prime
time include self-healing materials, where if the metal is
scratched or scuffed it is able to repair itself somewhat.
And some other technologies are just starting to see
usage in the fleet.
“In this past several years, [the Navy has] started
using high solids paint,” Kirkup said. “They use that in
tanks and preflight areas of ships. At some point, they’d
like to use it on the hull itself. They just need to prove
it’s the right application for it.” n