Every structure, big or small, needs maintenance every once in a while. We’ve already covered how scheduling conflicts can make this necessary process difficult to accomplish. So, imagine that the structure you’re in charge of maintaining is none other than the iconic Golden Gate Bridge! Talk about scheduling conflicts.
Some believe it’s painted every number of years. The fact is it’s painted continuously. The paint is a corrosion resistant coating that protects it from the salt in the water.
It was continuously spot-painted up until 1968 when it was realized that it needed to be repainted with inorganic zinc silicate primer and vinyl topcoats. In 1990 the top coat was changed to an acrylic emulsion, an FDA approved coating, to meet air quality requirements.
Today, painting continues based on assessments after inspections that determine where corrosion is advancing. Two of the major cables were repainted in 2012.
One of the biggest challenges, surprisingly, isn’t the people or traffic but the high salt content in the water and air. Not just the water it sits in, which makes a waterproofing company key, but the fog in the area has some of the highest salt content. This very actively deteriorates the paint and it also limits the hours during which the maintenance can happen. In fact, over 30% of the fiscal hours that were intended for bridge maintenance went unused due to weather conditions.
Thanks to the Golden Gate Bridge other metal structures that are similar are now pre-treated by sandblasting or flame cleaning. This greatly reduces the damage and therefore the cost of maintenance.
In the case of the Golden Gate Bridge, the majority of paint failure have been caused due to the loosening of mill scale. In order to fix this, crews have had to use pneumatic chipping hammers with specially-made studite-tipped tools was adopted as being the most economical. A flame dehydration torch is then passed over the metal which dries the material. This removes the moisture between the plates and around rivet heads and also removes all remaining traces of scale leaving a warm, dry surface to receive the priming coat. This surface is thoroughly wire-brushed and immediately primed while still warm and dry.
While you may not be dealing with the Golden Gate Bridge, regular maintenance of metal structures is important. Which is why the leading paint company in California is Raider Painting.