- cost of not galvanizing -
by Michael Martin, IZA

The Eiffel Tower, the landmark of Paris and symbol of France, was designed by Gustave Eiffel and constructed between 1887 and 1889, to commemorate the French Revolution which had taken place 100 years earlier. The tower was a revolutionary lightweight steel design, strong enough yet light enough to minimize wind loading and limit foundation loading, while being economic to construct and aesthetically pleasing. But alas, the steel was not galvanized.

The size and geometry of the tower place high demands on the corrosion protection and maintenance of the steel and makes maintenance particularly difficult. "It's just as important to be a good climber as a painter," according to one of the maintenance team. The maintenance operation takes place every seven years, lasts 14 months and uses 60 tons of primer and top coat paint on a total surface area of 200,000m2. During this operation, the 320 meter high tower is overhauled from top to bottom by a team of 25 painters who remove rust, bird droppings, loose paint and the damage caused by pollution from the city's atmosphere.

Amazed at the cost and complexity of the work involved in repainting the tower, where the painters must use hooks, ropes, safety nets and cannot begin painting each day until the morning dew has evaporated, a Dutch corrosion expert recently made a hypothetical calculation of cost savings had the Eiffel Tower been galvanized. He made a cost analysis comparing the application of a paint system with a so-called duplex system, whereby the steel is first galvanized with zinc and then painted. With a duplex system, any damage to the paint coating does not lead to corrosion as the steel continues to be protected by the zinc which underlies the paint.

Had the steel used to build the Eiffel Tower been galvanized before painting, only seven large-scale maintenance operations would have been required, compared to the 17 that have taken place since 1889. The first large-scale maintenance of a duplex system normally takes place after about 25 years (surface preparation and application of a primer and top coats). After this, small-scale maintenance (top coat) and large-scale maintenance take place alternately, after five or seven years respectively.

What does all this mean in terms of cost? Based on today's wage and price levels, and allowing for a favorable purchase price of the large quantity of paint needed, galvanizing before painting - the duplex system - would have saved at least $10 million in maintenance costs! Using modern day prices to calculate construction and erection costs, these savings amount to over 50% of the construction cost.

Although this is a lighthearted comparison, it illustrates why lifetime maintenance costs are so important when costing new infrastructure projects. When building for the future, better protect it with zinc!