There are a lot of good reasons to clean and maintain tanks that are storing wastewater, chemicals or petroleum (oil). Health and safety probably tops the list.
Over time heavy metals and chemicals can contaminate storage tanks containing certain types of fluids. Or in tanks holding petroleum, sludge can begin to build up. Also in storage tanks acids, caustics and other hazardous materials can form on the walls. In these cases cleaning out storage tanks periodically will help maintain safety levels, which will help keep those working around these tanks and materials safe as well. For all these reasons storage tank washing and cleaning becomes mandatory.
To clean most of these tanks, the contents are usually emptied and stored elsewhere. (Or if they are totally contaminated, they will be properly disposed of.) The insides of the tanks are first scraped out to remove and sludge or build-up along the walls, and then the pressure washer comes in. With the voluminous size of some tanks a simple hose will simply just not work too well. Water of about 220-degrees Fahrenheit with a pressure of about 3000psi should be effective in the cleaning of the tank floors, ceilings and walls. Then after the tank is clean, a vacuum truck can be utilized to pump out the water. Once clean and contaminant-free, the tank can be refilled with old or new contents.
Aside from contamination, there are some other reasons why storage tank washing is needed. For one, sometimes tankers in transport cause dangerous spills on roadways. This means that there could be explosive and/or hazardous material everywhere. In this case, pressure washers can be used to not only clean out the empty or even half-destroyed tank (to prevent more leaks as the tank is moved), but also to clean off the roadways. Other reasons a tank would need to be cleaned would be if they are being emptied of their contents to be sold, cleaning out tanks for renovations, making sure they are clean prior to scheduled inspections, if they are being disposed of (you do not want the chemicals to get into the groundwater) or finally, if they are being moved.
Because of the hazardous waste and materials that can build up in tanks, owners of these tanks should indeed invest in a pressure washer to do routine maintenance and storage tank washing. However, some prefer not to do this work on their own and this is why many pressure washing contractors may cater to industries such as this. If you are a contractor looking for this kind of work, targeting petroleum distributors, port authorities, government groups, public works departments and the like all use storage tanks and could be a great way to build business.
Just keep in mind using protective gear, while performing storage tank washing that contain dangerous vapors, and be sure to take extra precaution when working around explosive materials.