Modern technology has developed active pigments which are being incorporated into primers to provide additional protection. Active anticorrosive pigments are added to primers which can give further protection for areas with coating damage. These pigments prevent corrosion of a metal substrate by building up permanently passive conditions at the metal surface and/or by a build-up of solid compounds which fill the damaged area of the coating.
It is important to be flexible and adaptable when developing protective coating projects. While identifying areas of risk at the start of a project is an extra expense, it will help ensure a project’s success.
The Australasian Corrosion Association (ACA) works with companies like Remedy and NSB, along with academia, to research all aspects of corrosion to provide an extensive knowledge base that supports best practice in corrosion management, ensuring all impacts of corrosion are responsibly managed, the environment is protected, public safety enhanced and economies improved.
“The quality of the finished project is dependent on how skillfully and effectively a coating is applied,” Rigby said.
The technicians chosen to apply a coating must have apt skills. A less obvious criterion, especially for any sort of tower structure, is abseiling skills; technicians might have to be in a harness and
suspended in mid-air which requires a particular mix of physical and psychological attributes.
When planning protective coatings, it is also important to take account of factors such as the geography, access to the structure and climate, all of which impact the cost of the project.
According to Rigby, there are a range of quality tests available that comply with Australian and international standards, many of which are covered in the ACA’s NACE Inspector courses. A good coating specification will reference AS/NZ 2312 as a minimum and categorise the service environment according to its corrosivity and then nominate a coating system based on the desired design life of the coating.
One vital aspect of coatings projects is to have certification that the job complies with all the appropriate legislation, regulations and standards. There are two ways to achieve this; to pay for third party inspection and engage a contracting firm that has a PCCP accreditation. This ensures they have staff with the necessary skills and accredited processes, providing peace of mind to customers that quality is ‘built in’ throughout project planning and execution.
The cost to coat a structure with an appropriate and effective protective material varies depending on whether it is applied in a workshop or onsite and averages between $80 and $300 per square metre.
“This is a relatively minor cost, compared to the cost of not coating the steel,” said Ross.
“However, cost is very much relative to what the required durability expectation is, the level of aesthetics required and how harsh the environment is.”
If a structure to be protected is in a remote location, it will be necessary to select the most cost effective means of transporting materials and personnel to the site. Additionally, remote sites may be exposed to climatic extremes which impact on applying a coating. For example, monsoonal rains in tropical regions would make it difficult to spray a coating on to any type of structure.
The health and safety analysis of a project must look at how to effectively protect a structure and address any environmental considerations. It must also consider how to properly apply the coating to minimise its effects on the surrounding areas as well as protect the technician who might be working in a harness tethered metres above the ground.