Chapter 4 - Steel Surface Preparation by Hydroblasting

Abstract

This chapter focuses on the process of steel surface preparation by hydroblasting. Numerous factors affect the efficiency of hydroblasting processes, the most important factors of which are existing coating type, adhesion and condition, experience and organization of the working crew, geometry, and accessibility of the objects. For the treatment of complex geometries, such as communication towers, the main factors affecting the hydroblasting efficiency are location and access within the containment; and size and shape of existing members. A general cost structure of hydroblasting includes investment high-pressure unit; investment high-pressure tools; investment nozzle carrier heads; and nozzle wear. The major amount of the cost is covered by operator's wages. This situation, however, changes if mechanical or robotic machinery is applied, which in turn, increases investment cost. Hydroblasting has high injury potential as high-speed water jets can damage skin, tissue, and- if abrasives are involved - even bones. General sources of danger to hydroblasting operators include the reactive forces generated by the exiting water jets; cutting capability of the high-speed jets; and hose movements. To protect operators and those not directly in the blasting operation, the area around a work site required for the hydroblasting operation must be defined. The boundary of this area must be clearly marked by the hydroblasting team, providing both a visible and a physical barrier to entry by unauthorized personnel.