4. Why do we need to paint steel?
By far the single most important
reason is to protect a huge financial
investment by means of Corrosion
Prevention.
Ships, factories, oil refineries etc
cost millions of dollars to build – we
can not just let them rust away.
12. What is Corrosion
Corrosion is basically:-
“The attack on metals by their environment.”
We normally see it as steel changing to rust.
Nature is simply returning steel from an unstable man-
made state to a stable natural state.
13. Corrosion
STEEL
Iron Metal
Chemically Unstable
Structural
HEAT CORROSION
(By Man) (By Nature)
Chemically
the same!
IRON ORE RUST
Iron Oxide Iron Oxide
Chemically Stable Chemically Stable
Non-Structural Non-Structural
14. Corrosion
• Steel corrodes…
• Rust is weak…
• Rust is porous…
• Rust detaches from the steel…
• Rust does not prevent more corrosion…
…..…SO WHY USE STEEL?
15. Why use Steel?
• Iron ore is very widely available.
• It is easy to make steel from iron ore
• Steel is strong relative to its weight
• STEEL IS CHEAP!!!!!
23. Fouling
Shoreline animals released as tiny larvae:-
• Hydroids - can swim for just a few hours
• Barnacles - can swim for up to 6 weeks
…if they do not find a surface to colonise in that
time they die.
28. Why do we use Antifoulings?
We are used to the idea of fast moving items having to
be streamlined to go smoothly through air
29. Why do we use Antifoulings?
……but the same principles apply for ships passing through
water – albeit at much slower speed.
30. Why do we use Antifoulings?
Drag on ships comes from roughness due to corrosion & fouling!
Although a barnacle seems very small compared to a ship,
if there are enough of them, it will greatly increase fuel costs..
BECOMES
44. Marine vs PC
• We do not use the same coatings for both Marine &
PC tanks.
• PC Tanks hold one chemical for many years.
• Marine Tanks hold cargoes for short periods and
then have to be able to carry a totally different cargo.
45. Why do we need to paint steel?
1) Corrosion Prevention
2) Fouling Control
3) Cosmetic Appearance
4) Cargo Storage / Carriage
5) Abrasion Resistance
59. Radar Absorption
• Some navies require special coatings for above-water
areas to make them ‘invisible’ to radar.
• These are very specific types of coatings for each
navy and developed in great secrecy.