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Effect of Additional Water-Jet Cleaning on the Surface Cleanliness and Coating Performance

The objective of surface preparation is to create proper adhesion of a coating over the substrate. Proper surface preparation is vital to the long life and effectiveness of a coating applied in corrosive service. In some projects, the owners ask for the additional water jet cleaning prior to blasting work. 

Product Number: 51219-202-SG
Author: Heebaek Lee, Eunha Song
Publication Date: 2019
Industry: Coatings
$0.00
$20.00
$20.00

The objective of surface preparation is to create proper adhesion of a coating over the substrate. Proper surface preparation is vital to the long life and effectiveness of a coating applied in corrosive service. In some projects, the owners ask for the additional water jet cleaning prior to blasting work. The purpose of high-pressure water jet cleaning is to improve the corrosion resistance of the coating by removing oil or grease affecting coating quality, by preventing pH changes on the surface that may occur during solvent cleaning, and by managing the soluble salts to below 18mg/m2Cl-. But the process problems by water jet cleaning are removal of the residual waste water, process delays caused by adding drying process, freezing problems with the residual washing water in the winter period, and the costs of disposal of waste water. Therefore, it was required to optimize the surface treatment criteria by evaluating the coating performance and the surface cleanliness according to water jet cleaning. Surface cleanliness was evaluated by the surface pH variation, dust grade (ISO 8502-3), and soluble salts level (ISO 8502-6), and Coating performance was also evaluated by salt fog spray and condensation test in accordance with ISO 12944. The results show that the water jet cleaning prior to blasting does not affect the surface cleanliness and coating performance. Consequentially proper blasting surface treatment without water jet cleaning can give the required coating performance in the vessel and offshore structure.

The objective of surface preparation is to create proper adhesion of a coating over the substrate. Proper surface preparation is vital to the long life and effectiveness of a coating applied in corrosive service. In some projects, the owners ask for the additional water jet cleaning prior to blasting work. The purpose of high-pressure water jet cleaning is to improve the corrosion resistance of the coating by removing oil or grease affecting coating quality, by preventing pH changes on the surface that may occur during solvent cleaning, and by managing the soluble salts to below 18mg/m2Cl-. But the process problems by water jet cleaning are removal of the residual waste water, process delays caused by adding drying process, freezing problems with the residual washing water in the winter period, and the costs of disposal of waste water. Therefore, it was required to optimize the surface treatment criteria by evaluating the coating performance and the surface cleanliness according to water jet cleaning. Surface cleanliness was evaluated by the surface pH variation, dust grade (ISO 8502-3), and soluble salts level (ISO 8502-6), and Coating performance was also evaluated by salt fog spray and condensation test in accordance with ISO 12944. The results show that the water jet cleaning prior to blasting does not affect the surface cleanliness and coating performance. Consequentially proper blasting surface treatment without water jet cleaning can give the required coating performance in the vessel and offshore structure.

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