- Waldman, Jonathan.
Rust.
New York: Simon & Schuster, 2015.
ISBN 978-1-4516-9159-7.
-
In May of 1980 two activists, protesting the imprisonment of a Black
Panther convicted of murder, climbed the Statue of Liberty in
New York harbour, planning to unfurl a banner high on the
statue. After spending a cold and windy night aloft, they
descended and surrendered to the New York Police Department's
Emergency Service Unit. Fearful that the climbers may have
damaged the fragile copper cladding of the monument, a
comprehensive inspection was undertaken. What was found was
shocking.
The structure of the Statue of Liberty was designed by
Alexandre-Gustave Eiffel,
and consists of an iron frame
weighing 135 tons, which supports the 80 ton copper skin.
As marine architects know well, a structure using two
dissimilar metals such as iron and copper runs a severe risk
of galvanic corrosion, especially in an environment such as
the sea air of a harbour. If the iron and copper were to
come into contact, a voltage would flow across the junction,
and the iron would be consumed in the process. Eiffel's
design prevented the iron and copper from touching one
another by separating them with spacers made of asbestos
impregnated with shellac.
What Eiffel didn't anticipate is that over the years
superintendents of the statue would decide to “protect”
its interior by applying various kinds of paint. By 1980 eight coats
of paint had accumulated, almost as thick as the copper skin. The
paint trapped water between the skin and the iron frame, and this set
electrolysis into action. One third of the rivets in the frame were
damaged or missing, and some of the frame's iron ribs had lost two thirds
of their material. The asbestos insulators had absorbed water and
were long gone. The statue was at risk of structural failure.
A private fund-raising campaign raised US$ 277 million to
restore the statue, which ended up replacing most of its
internal structure. On July 4th, 1986, the restored statue
was inaugurated, marking its 100th anniversary.
Earth, uniquely among known worlds, has an atmosphere with
free oxygen, produced by photosynthetic plants. While much
appreciated by creatures like ourselves which breathe
it, oxygen is a highly reactive gas and combines with
many other elements, either violently in fire, or more slowly
in reactions such as rusting metals. Further, 71% of the Earth's
surface is covered by oceans, whose salty water promotes
other forms of corrosion all too familiar to owners of boats.
This book describes humanity's “longest war”: the
battle against the corruption of our works by the inexorable
chemical process of corrosion.
Consider an everyday object much more humble than the
Statue of Liberty: the aluminium beverage can. The modern can
is one of the most highly optimised products of engineering
ever created. Around 180 billion cans are produced and consumed
every year around the world: four six packs for every living human
being. Reducing the mass of each can by just one gram will result
in an annual saving of 180,000 metric tons of aluminium worth
almost 300 million dollars at present prices, so a long list of
clever tricks has been employed to reduce the mass of cans.
But it doesn't matter how light or inexpensive the can is if
it explodes, leaks, or changes the flavour of its contents.
Coca-Cola, with a pH of 2.75 and a witches’ brew of ingredients,
under a pressure of 6 atmospheres, is as corrosive to bare
aluminium as battery acid. If the inside of the can were not
coated with a proprietary epoxy lining (whose composition
depends upon the product being canned, and is
carefully guarded by can manufacturers), the Coke would
corrode through the thin walls of the can in just three days.
The process of scoring the pop-top removes the coating around
the score, and risks corrosion and leakage if a can is stored on
its side; don't do that.
The author takes us on an eclectic tour the history of corrosion
and those who battle it, from the invention of stainless steel,
inspecting the trans-Alaska oil pipeline by sending a “pig”
(essentially a robot submarine equipped with electronic sensors)
down its entire length, and evangelists for galvanizing (zinc coating)
steel. We meet Dan Dunmire, the Pentagon's rust czar, who estimates
that corrosion costs the military on the order of US$ 20 billion
a year and describes how even the most humble of mitigation
strategies can have huge payoffs. A new kind of gasket
intended to prevent corrosion where radio antennas protrude
through the fuselage of aircraft returned 175 times its investment
in a single year. Overall return on investment in the projects
funded by his office is estimated as fifty to one. We're introduced
to the world of the corrosion engineer, a specialty which, while
not glamorous, pays well and offers superb job security, since rust
will always be with us.
Not everybody we encounter battles rust. Photographer
Alyssha Eve
Csük has turned corrosion into fine art. Working at the
abandoned Bethlehem Steel Works in Pennsylvania, perhaps the rustiest
part of the rust belt, she clandestinely scrambles around the
treacherous industrial landscape in search of the beauty in
corrosion.
This book mixes the science of corrosion with the stories
of those who fight it, in the past and today. It is an
enlightening and entertaining look into the most mundane
of phenomena, but one which affects all the technological
works of mankind.
January 2016 