Observations on Using Water Jetting to Clean Surfaces

April 5, 2009

Main Library

A Primary Mission of the Council is to promote effective means of surface preparation in the maintenance industry using water and water/abrasive blasting techniques.

Waterjetting can be used to remove existing coating, rust, surface oil and grease, and water-soluble surface contaminants.1 The water is propelled through a single nozzle or multiple nozzles on a rotating head.

During on-site visits, Corrpro Companies, Inc. observed the Ultrahigh-Pressure Waterjetting process on three different bridge structures, and gathered data from a fourth.

All of the waterjetting equipment was supplied by Commonwealth Waterjetting Group, Jamestown, RI.

Commonwealth also provided training and technical support since this was the first time the contractor performed UHP waterjetting.

The production rate observed for waterjetting in New Hampshire was approximately 142 ft2/man-hr.

Waterjetting produces no dust, which means that less personal protective equipment is necessary to maintain adequate worker health and safety.

The lead levels sampled during waterjetting never reached the permissible exposure limit of 50 g/m3, however, the measurement techniques may not be optimized to sample water mist.3 Weather affects waterjetting different from dry abrasive blasting.

The Joint SSPC/NACE Task Group on Surface Preparation is currently reviewing the criteria and requirements for flash rusting, as “light” flash rusting is not considered to have a detrimental impact on the performance of the coating system.

The current state-of-practice for a spot repair scenario is hand-tool/power-tool cleaning.

However, in order to make a comparison of waterjetting to the current state-of-practice for a spot repair scenario, consideration must be given to the extent of coating deterioration.

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