Shot Blasting Becoming A Thing Of The Past
Shipping Container News
15 years ago a container repair depot without a full refurbishment facility including shot blast bay would have been unthinkable. Back then new box prices could be more than double today’s price, lease rates were much higher as were freight rates and there was less competition. The upside of this was that companies spending a considerable amount to have their equipment built would finance them over longer periods and the useable life expectancy of a shipping container would generally be more than double that which we see today.
In order to run this equipment for this amount of time a significantly higher level of maintenance would have to be carried out, including preventative maintenance. In addition to this the revenue earned from the equipment also generated a budget for some companies to carry out cosmetic repairs in order to maintain a corporate image. This preventative maintenance and cosmetic work would often involve containers being shot blasted to remove all but the most negligible, minor corrosion, and then resprayed with a zinc rich primer and topcoat to protect the steel and improve the brand image of the equipment. Such was the frequency of boxes needing refurbishment that companies sprung up just to service this market, carrying out only shot blasting in fully automated workshops.
Various factors over the years have led to a dramatic decline in companies providing this service. The process itself is a lengthy and costly exercise. Firstly the shipping container needs to be shot blasted back to bare metal, a process which has to meet Swedish Standard 2.5 for the preparation of bare metal, including the underside. Next the interior and or exterior has to be sprayed with a zinc rich primer. Once this first coat has dried an additional topcoat must be applied. The underside would need to be coated with bitumen or Tectyl. Over time the cost to carry out a full refurbishment began to exceed the cost to purchase a new box in China.
Environmental concerns and regulation also added to the cost and eventual decline of shot blasting shipping containers. Laws were passed forcing companies to recycle any shot meaning older plant had to be upgraded at significant cost or replaced. The materials used for the blasting process too needed to be replaced by more resilient and much more expensive materials. The force of the individual grains being fired using compressed air, with huge force, against a steel box would leave very little to be recycled and re-used. Health concerns with the use of silica based shot and the by-products of the process also led to companies needing to issue those carrying out the work with clean air fed suits, and dedicated, vented spray shops.
Now days container owners spend very little on refurbishment or preventative maintenance and the lower cost of production coupled with low lease and freight rates means that the life expectancy of a container is much shorter.