Page 416 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

394 CONSEQUENCES OF CORROSION

Corrosion of power cables such as “sheath damage” or “water in the cable” is also
a challenging problem. Some of the causes of damage to the protective sheath range
from gunshot damage and pinholes caused by lightning strikes on overhead lines to
rodent damage, attack by gophers and squirrels, and damage by termites or other
insects. Problems with buried cables were solved by replacement.
About 75 years ago, the main material for cable sheathing was lead, protected
from corrosion by asphalt-impregnated jute coating. Even then corrosion problems
prevailed. Later on, extruded or drawn aluminum sheaths were in use, soon to com-
pete with polythene. A large number of failures in the 1960s caused by water in the
cable led to the development of sophisticated methods of sheathing involving coated
aluminum and clad metals of copper adjacent to a number of steels (45).

5.11 THE MARINE AND OFFSHORE INDUSTRY

The marine environment is probably the most aggressive environment in which met-
als are chosen to operate. The corrosion performance is mixed. Great achievements
have been made offshore since the development of a new generation of deep-water
platforms in the North Sea oilfields during the 1970s. This technology has been
used in deeper waters. Over 200 of the largest steel structures have been created and
immersed in violent seas, and continued operation without failure for 25 years is sur-
prising and true. The record is successful but for the Piper Alpha disaster in 1988
when 167 men died because of a fire following a mechanical failure.
The battle against corrosion was first waged with hulls made of puddled iron start-
ing with the construction in the Scottish Clyde shipyard of the fast passage barge,
Vulcan, in 1819. In 1822, Manby was the first iron steamship to make an international
voyage under power. Both marine fouling and corrosion problems were faced by iron
hulls of the ships (46). In spite of the difficulties, many of the iron hulls gave long
years of service and survived well, even when lost or abandoned, as in the example
of the submarine Holland I.
In spite of many advances made in materials (47) and coatings technology, civilian
merchant fleets have suffered badly from poor maintenance by owners leading to
major disasters, most of which is attributable to corrosion and poor maintenance at
every level. The loss of the 170,000 ton Derbyshire in 1980 with all 44 crew members
is speculated to be because of poor design, accentuated by corrosion.
In the 1990–1991 time span, more than 30 bulk carriers were lost or damaged and
more than 300 crew members died. A surveyor found corrosion from original 12 mm
thickness down to 3–5 mm of steel during 10–15 years of life. For a long time, the
owners cut their ship maintenance costs, which led to extensive corrosion and loss of
lives.
In 1993, the oil tanker Braer went aground, discharging about a 100,000 ton
cargo onto the ecosystem of Shetland Islands to the north of Scotland. The accident
resulted from the failure of a marine propulsion system after seawater was ingested
in the storm. The blame for this rests on the cost-cutting practices endemic in the
industry.