Resources frittering away

This Issue This is a part of the Corrosion feature

By - , Build 113

Every good rocker knows that ‘rust never sleeps’, but how much does corrosion cost the country, and how can this be reduced?

Think about a rusty roof. What is the cost of lost weathertightness? As well as the cost of the roof replacement, there are the indirect costs such as water damage to the building contents and the inability to use the building while the roof is being replaced. These indirect costs are usually much higher than the direct replacement cost. Prudent materials selection, protection and maintenance might have removed a lot of these costs.

Up to 40% of corrosion avoidable

A report in 1971 delivered what was astounding news at the time – 3.5% of GDP in the United Kingdom was lost to corrosion every year. Some materials degradation is inevitable if we don’t gold-plate everything, but the study’s killer conclusion was that a quarter of the loss was cost-effectively avoidable using knowledge that was already available but was just not being used.

There have been similar studies of the national cost of corrosion in other countries. All of them have indicated 1–5% of GDP is lost to materials degradation and between 10–40% of it is avoidable.

The most recent major study was in the United States over 1999–2001. This indicated around 3.2% of US GDP was still being lost as direct costs of materials degradation. It was estimated that 15% of the bridges in America were structurally deficient, primarily due to corrosion of steel and steel reinforcement. The annual direct cost of corrosion for highway bridges was estimated at US$8.3 billion. Lifecycle analysis estimated indirect costs to users from traffic delays and lost productivity at more than 10 times the direct cost of corrosion maintenance, repair and rehabilitation. The National Highway Bridge Inspection and Reconstruction Act has since created tough new standards for bridge safety and authorises expenditure to repair structurally deficient and functionally obsolete bridges across the nation.

New Zealand not immune

The economic impact of materials degradation has never been measured properly for New Zealand, but nothing suggests the economic impact will be any less here than in other countries. Having a mostly temperate climate, being located on islands with the majority of urban development close to the coasts and having strong onshore winds carrying sea salt inland all contribute to corrosion.

New Zealand’s moist atmosphere combines with solar radiation to damage inappropriately formulated plastics very quickly, and the sulphur-containing gases in the geothermal zone can wreak havoc on improperly selected materials.

Assuming just 0.3% of New Zealand’s GDP (probably an underestimation) is lost due to avoidable materials degradation each year translates to $0.4 billion.

Fortunately, there are people who are working to avoid this loss to New Zealand.

BRANZ corrosion research

BRANZ corrosion programmes have been running for over 30 years and have been responsible for mapping New Zealand for atmospheric corrosion of metals in the 1990s and, over the last decade, for mapping the hazards of breakdown of polymers in New Zealand atmospheres. A programme in the 1970s and 1980s provided extensive information on product selection (especially for flooring finishes) in the demanding environments of food processing plants.

Programmes over the 30 years have addressed problems of fastener corrosion in treated timber and provided extensive information for the materials degradation section of NZS 3604. The BRANZ Materials staff have studied the durability under New Zealand conditions of paints, sealants, concrete and every product or system that has received a BRANZ Appraisal certificate. Their work is reflected in all of the publications that BRANZ produces.

Corrosion Association fights against corrosion

BRANZ is not alone in delivering information on materials degradation and how to avoid it. The New Zealand branch of the Australasian Corrosion Association has counterparts in each of the Australian states and links to international corrosion organisations. Their library is housed at HERA in Auckland. Information on their activities is available at

The New Zealand branch has around 150 members from a range of research, consultancy, materials supply and specialist contracting backgrounds, all of whom are interested in helping New Zealand avoid these unnecessary costs. The association runs regular seminars and training courses and is seeking to work with the Institution of Professional Engineers New Zealand and their Futureintech programme to get educational resources on materials degradation into New Zealand schools.

Poor material selection or protection costs

Despite this activity, we still see examples every day of poor materials selection or protection of materials in service, which costs the building owner, and ultimately the nation, unnecessarily.

I come back to the finding of that United Kingdom report in 1971 – a quarter of the cost of corrosion to the nation could have been avoided cost-effectively by applying knowledge that already existed. BRANZ and all the members of the New Zealand branch of the Australasian Corrosion Association would like to see this eliminated for New Zealand.

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