Corrosion Protection Strategies for Coal Export Facilities in Abbot Point and Gladstone

Application of Abrasive Blasting and Protective Coatings in High Corrosion Areas of

Mackay, Townsville, Abbot Point and Gladstone

Coastal towns such as Mackay, Townsville, Abbot Point and Gladstone share one thing in common—they are major contributors to Australia’s coal industry, exporting massive quantities of this type of fuel annually. Coal export facilities face unique challenges, one of which is managing corrosion. Strategies for managing corrosion include abrasive and grit blasting and applying protective coatings, corrosion inhibitors, cathodic protection and the use of corrosion-resistant alloys. The appropriate corrosion protection depends on the type of metal being corroded, temperature and conditions of a corroding environment.

Corrosion refers to the gradual deterioration or degradation of a substrate material, usually metals such as steel, iron and aluminium which are used in coal export facilities. Corrosion can occur uniformly across a surface (general corrosion) or at localised portions of a material (pitting corrosion). Coal export facilities usually suffer from general corrosion which results in loss of thickness of a structural component, decreasing its structural resistance and strength. Exposure to certain environments contributes to corrosion, such as:

• Immersion in sea water
• Exposure to an enclosed atmosphere
• Exposure to porous cargo
• Impact and abrasion from cargo handling equipment

Coal facilities such as rail infrastructure, coal stockyards, and conveyers are composed of metal parts which are susceptible to corrosion. Pipelines, which are onshore, also face serious risks of damage. Exposure to coal, which is highly abrasive, moisture-laden and filled with corrosive elements, gradually causes corrosion in most metal facilities.

Methods of corrosion protection

• Cathodic protection: Corrosion is an electrochemical reaction consisting of an anode and a cathode. In an electrochemical reaction, corrosion occurs at the anode. Thus, cathodic protection involves the introduction of a sacrificial anode such as magnesium material, at which corrosion occurs while sparing the protected material.
• Corrosion inhibitor: Corrosion inhibitors are substances which are added in small concentrations to an environment of a metal. The inhibitor slows down the corrosion rate of the metal exposed to the treated environment. Inhibitors are generally used for internal corrosion which can occur in carbon steel pipes and vessels. It is a corrosion control method which is less expensive than corrosion-resistant alloys.
• Corrosion-resistant alloys (CRAs): Certain alloys such as stainless steel, nickel-base alloys and titanium alloys, are able to fight corrosion and are used when corrosive conditions prevent the use of carbon steels and when protective coatings are unable to provide adequate corrosion protection or are not economically feasible. CRAs are highly effective but the costs can be prohibitive.
• Metallic coating: Another effective corrosion protection technique is galvanising, a system which involves the application of metallic zinc to carbon steel. Hot dip galvanising, as the name suggests, is the process of dipping the steel member into a bath of molten zinc which protects steel from corrosion by serving as the sacrificial anode. Hot dip galvanising plants, however, are limited and not available in the coal mining towns of Mackay, Townsville Abbot Point and Gladstone. Transporting materials to and from galvanising plants can add to corrosion protection costs and expose galvanised material to damage while in transit.
• Protective coatings: Metallic substrates such as carbon steel ordinarily deteriorate without protective coatings. Plastics and polymers are protective coatings which are highly favoured in corrosion control because they not only slow down degradation but are also lightweight unlike metallic coatings, economical unlike corrosion-resistant alloys, and strong. Examples of protective coatings include polyurethane, polyurea and rubber.
• Surface preparation: Any application of protective coating or other corrosion control method requires a clean and contaminant-free surface for the chosen corrosion prevention system to succeed. Without adequate surface preparation such as abrasive blasting, hydro cleaning or other surface preparation technique, even the best corrosion prevention system will fail.

Girt and Sand blasting involves the application of abrasive material propelled by strong pressure against a substrate to be cleaned. The result is a smooth and clean surface that is free of rust, dirt and other contaminants which may otherwise prevent the protective coating from bonding well with the substrate.

After obtaining a clean surface through surface preparation, protective coatings such as polyurea or polyurethane may be applied to the substrate, forming a tight barrier between the substrate and its corrosive environment. Successful protective coatings also depend on the selection of the appropriate coating, correct application according to manufacturer specifications and the experience of the corrosion protection professional.

Corrosion is a common challenge in coal export facilities in Mackay, Townsville, Abbot Point and Gladstone. Preventing or delaying degradation of structures and equipment is essential in order to prevent serious damage to equipment and exposing the community and the environment to danger. Corrosion protection is a cost effective solution which can prolong the life of coal export facilities. Various corrosion protection strategies are available and an experienced professional can help companies determine the best combination of surface protection such as abrasive blasting and protective coatings for their needs. Diamond Protective Coatings have been solving their clients corrosion protection problems for over 20 years.  Call Dennis 0417 603 265 for further advice.