PROTECTION AGAINST CORROSION

Protection of Ships

Lecture 1: Protection against Corrosion

Lectures 2, 3: Protection against Fouling

Colin Anderson

(Business Manager – Antifoulings, International Paint)

 

Lecture 1: Outline

• Introduction

• Corrosion Processes

• Control of Corrosion

• Introduction to Paint

• Anticorrosion Coatings

• Ballast Tank Coatings

 

Protection of Ships against Corrosion

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The design and maintenance of ships requires a knowledge of corrosion:

– Specification and life-time (Fatigue life, use of HTS etc.)

– Age-related defects of single and double hull tankers

– “Survey-friendly” design (ease of access to inspect and repair)

– Quality of build and outfit (fit up of blocks, quality of finishes)

– Tank cargoes (and tank ullage space)

 

Corrosion Processes

Extraction of a pure metal from its ore state requires energy, and it is this energy which makes metals inherently unstable and seek to react with their environment.

Metals which have a higher energy input in their production processes are more susceptible to corrosion, and have a lower electrical potential.

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There are 2 main types of corrosion on ships:

– Atmospheric

– Immersed

The three essential elements necessary for corrosion to occur are:

– Water

– Contaminants in the water (eg salts)

– Oxygen

Corrosion is primarily electrochemical in nature, with a chemical reaction accompanied by the passage of an electrical current.

In order for this to happen, a difference in electrical potential must exist between different areas of the substrate

 

Read  Lecture 1   – Protection against corrosion