Hydroblasting Applications on Steel Surfaces

Hydroblasting is a surface cleaning method using a water jet created by a high-pressure spray gun or nozzle to clean the surfaces of various materials (such as steel, stone, concrete, plastic and wood). This process provides an excellent adhesion surface for coating renewal, surface repair or maintenance. The absence of any abrasive solid material during the impact of the water's high-pressure energy on the surface provides a significant advantage. As a result, it eliminates the problems of solid media pollution and abrasive disposal, creating an environmentally friendly alternative to grit blasting.

Two types of hydroblasting applications exist depending on pressure range:

1. Low-pressure water cleaning (LPWC): Applied at water pressures below 340 bar (<5000 psi). The objective is to remove marine organisms from the environment, residual paint, dust and corrosion products from steel surfaces before the main cleaning operation. This process is not considered a preparation method, but rather a pre-treatment of the surface before the main cleaning method is applied. 2. High-pressure water cleaning (HPWC): High-pressure water cleaning refers to water pressures between 340 - 680 bar (5000 - 10000 psi). At these pressures, loose rust and coatings in surface cavities can be removed, but a uniform matte appearance cannot be achieved. 3. High-pressure water jet (HPWJ): High-pressure water jet refers to water pressures between 680 -1700 bar (10000 – 25000 psi). In applications, high-pressure water jet can perform most of the surface cleaning and preparation tasks encountered in ship repair, shipbuilding or industrial environments. Its performance may only be insufficient when encountering some very difficult coatings or mill scale, when a higher pressure needs to be used. 4. Ultra high-pressure water jet (UHPWJ): Refers to water pressures above 1700 and up to 3000 bar (25000 – 43500 psi). Some of the newest marine coatings require surface preparation to this level. Hydroblasting Applications: • Paint removal, • Hull cleaning, • Concrete demolition (hydro demolition), • Chloride removal from concrete, • Asbestos cleaning with high-pressure water, • Pool renovation, • Precision casting part cleaning, • Pipe scale removal, • Rust cleaning, • Surface preparation in marine structures, • Kiln cleaning in cement plants, • Coating preparation, • Concrete surface preparation, • Tank cleaning with special nozzles, • Descaling with high-pressure water jet. Visual Conditions of Surface Cleanliness WJ-1: The surface shall be free of all visible rust, coatings, mill scale and foreign matter previously present and shall have a matte metal finish. WJ-2: The surface shall be cleaned to a matte finish with at least 95% of the surface area free of all previously existing visible residues and the remaining 5% containing only randomly distributed stains of rust, coating and foreign matter. WJ-3: The surface shall be cleaned to a matte finish with at least two-thirds of the surface area free of all previously existing visible residues and the remaining third containing previously existing randomly distributed stains. It shall be free of rust, residual coatings and foreign matter. WJ-4: All loose rust, loose mill scale and loose coatings shall be equally removed from the surface.

References • https://www.coralccpc.com/hydroblasting/ • http://pressurejet.com/pages/70/Hydro_blasting_Machine.aspx • https://hydroblast.co.uk/ • https://www.rileyindustrial.com/hydroblasting-pressure-washing • https://www.aquajetsme.com/hydro-blasting • https://dionisopoulos.com/hydroblasting/

Assoc. Prof. Dr. Ekrem Altuncu TÜYİDER (All Surface Processing Association) Member, Sakarya University of Applied Sciences Director of the Materials and Production Technologies Application and Research Centre - SUMAR