Shot blasting is a method used to clean/ remove rust and surface contaminants from steel. The main reason for carrying out this process is to obtain excellent cleaning and surface preparation for secondary finishing operations. The shot blasting process uses compressed air for propelling steel shot in a controlled manner on to the steel component removing all contaminates.
At BoA we have an auto blasting machine which blasts to an SA 2.5 standard and a new manual shot blaster which blasts to an SA 3 standard. The manual shot blaster was purchased after BoA secured project Riverlight. This project encompassed a structural and architectural prop system situated on the building exterior. With the project being located on the River Thames it required all steelwork to be C4 protected which is an inland industrial and urban high corrosion category. Due to the size and detail of the props galvanising was not an option, therefore an alternative had to be explored. This alternative is called Zinc Arc spraying, which gives the same 15 year protection guarantee as galvanising. However the Zinc Arc spray option could only be utilised if the surface it's applied to is blasted to an SA 3 standard. This is because the zinc needs a rougher surface to enable it to adhere to the steel. Having the ability to carry out manual shot blasting has allowed BoA to provide a Zinc Arc spray finish as an alternative to galvanising, giving the option to protect more complex components and control coating thickness.