Basic principle of high-pressure jetting
High-pressure water jetting uses a pump capable of generating pressures up to several thousand bar to convert water into an energy-concentrated jet. Water is forced through an extremely small orifice in the nozzle (typically 0.1–0.8 mm diameter), accelerating it to speeds of up to 900 m/s — nearly the speed of sound. When this jet strikes a surface, it transfers its kinetic energy which dislodges contaminants, coatings, rubber, deposits and concrete. The key difference from abrasive methods is that water itself is non-abrasive — it cleans purely through kinetic energy.
Key parameters
Pressure alone is insufficient to assess effectiveness. Alongside it, crucial factors include: water flow rate (L/min) determines energy delivered per unit time, nozzle orifice diameter affects jet density (smaller = sharper cut), standoff distance from the surface (typically 100–400 mm — too close causes grooving, too far reduces effect), impact angle (90° for maximum cutting power, 30–45° for gentler cleaning), travel speed of the nozzle across the surface (slower movement = more removal) and nozzle type (rotating nozzle with spinning head achieves better coverage than a stationary nozzle).
Applications in construction and industry
- Removal of old coatings and paints from steel and concrete structures
- Cleaning cracks, expansion joints and surface deposits
- Surface preparation before applying new coatings, bonding or welding
- Removal of rubberised surfacing from industrial floors and bridge decks
- Demolition of thin reinforced concrete slabs and remediation of deteriorated structures
- Cleaning pipes, heat exchangers and industrial tanks
- Preparing concrete surfaces for mechanical keying of new concrete
- Removing asphalt, adhesives and other adherent materials
Typical pressure ranges and their use
Low pressure 200–400 bar is primarily used for gentle area cleaning, removing loose deposits and rinsing surfaces. Medium pressure 400–700 bar is most commonly used for cleaning metal structures, removing corrosion products, rust and thin coatings. High pressure 700–1,500 bar is used for thicker coating layers, rubber and polymer material removal. Extreme pressure above 1,500 bar (up to 3,000 bar) is used for concrete demolition work, heavy corrosion layers and specific industrial applications. For most routine jobs, pressure up to 700 bar is sufficient — higher pressure is not always better and can cause unintended damage.
Method limits
High-pressure water jetting has limits that must be respected. The method does not remove loosened contaminants on its own — slurry and wastewater are generated that must be captured, separated and properly disposed of. On steel it typically does not create an anchor profile like blasting does — additional treatment or a coating system compatible with a smoother surface is required. Flash rust on steel within hours of processing requires immediate protection application. On sensitive substrates such as thin sheets or already damaged structures, excessive pressure can be destructive. Therefore, test cleaning on a small sample is always essential.