KEY POINTS:
The headline read "Historic wharf's decay comes as a shock" and as one read through, it was obvious the corroding wharf at Devonport was not an issue of neglect but of ignorance.
Let's be honest; an 80-year-old steel reinforced concrete structure sitting over seawater is going to have
issues. And it should be pointed out that the corrosion in question takes years to appear, so it's hardly what I would call surprising.
This is just a small example of the problems that society has with corrosion. We don't like seeing rust on our cars, lawnmowers or barbecues. It shortens the expected life and we resolve to choose more carefully next time.
According to the World Corrosion Organisation, the worldwide cost is US$1.8 trillion or 3 per cent of the world gross domestic product annually. That would be about $5.4 billion to the New Zealand economy or around $25 per person each week. That is the money we spend on protecting things from corrosion, repairing items and buying alloys and corrosion-resistant materials.
In the case of Victoria Wharf, the concrete is old and porous; sea salt permeates through to the steel reinforcing bar which rusts. In doing so it expands, then the concrete cracks propagate, more salt gets to the steel and the cycle continues. This concrete cancer is just one example.
We all remember the Auckland-wide power blackout in June 2006 when a small component at the Otahuhu substation failed. The supposed $10 shackle became a multimillion-dollar expense to Auckland, lending credence to the idea that the indirect or collateral cost of corrosion is as much as twice the direct cost.
So how does an annual rust tax of over $2600 for every New Zealander sound? Well, there are a number of ways to reduce these numbers. The first is to understand that corrosion is not inevitable. There are ways to reduce or manage it.
Education and information are critically important but the call from corrosionists has fallen on deaf ears for many years. It's only when some disaster occurs such as the Minnesota Bridge collapse or the pipeline leak in Prudhoe Bay, Alaska, that the hitherto deaf ears prick up.
Environmentalists will eventually work out that corrosion prevention is actually good for the planet. Our assets and infrastructure, from barbecues to bridges, took energy to produce. Corrosion engineering protects those assets and reduces energy demands and the subsequent impact on the environment.
The US Government have a bill before Congress that will amend the tax laws to encourage the use of corrosion prevention and mitigation measures.
Maybe our leaders could consider this innovative type of legislation; it might help the owners of decaying wharves rest at night.
* Mike Boardman is president of the Australasian Corrosion Association.
