Significance and Use
The appearance of the various degrees of dry and wet abrasive blast cleaning, hand and power tool cleaning and water jetting are influenced by the initial rust grades of the steel being cleaned and/or the type and condition of the coating on the existing steel. The standards and guides aid visually in judging and evaluating the degree of rusting and/or paint deterioration before cleaning and the degree of cleaning of steel surfaces prior to painting.
Five methods have evolved because of differences in the practice of using visual standards and guides throughout the world, and the method of surface preparation employed. In Europe, the visual standards (Method A) are used as the primary means of assessing the degree of cleaning. In the US, the SSPC written definitions take precedence with the visual guides and reference photographs used as a supplement. The visual guides and reference photographs of Methods B, C, and D conform to the SSPC written definitions. There are no written definitions for Method E.
1.1 The visual surface preparation standards consist of a series of color prints available as separate publications. Five different sets of photographs are described in this standard, designated as Method A (ISO/Swedish Standard ) and Methods B through E (SSPC Guides and Reference Photographs ). The methods differ in the depiction of the initial surface, in the definition and depiction of the cleaning conditions, and in the number of cleaning methods included. Because of these differences, the specifier should state which method to use.
1.2 The colored visual surface preparation standards represent different conditions of hot rolled carbon steel before and after surface preparation. Prior to cleaning, there are four rust grades, A to D, that cover the range from intact mill scale to 100 % rusted and pitted steel. The standards then depict the appearance of the initial conditions after cleaning by one or more methods (for example, dry abrasive blast cleaning) to various degrees of thoroughness. In addition, Method B includes three painted conditions that contain various degrees of deterioration. The Guide depicts these conditions after various degrees of dry abrasive blast cleaning. Method C includes four rust grades and three painted conditions that contain various degrees of deterioration. The Guide depicts these conditions after various degrees of hand and power tool cleaning. Method D includes two rust grades and four painted conditions that contain various degrees of deterioration. The Guide depicts these conditions after various degrees of water jetting, with three levels of flash rusting. Method E includes two rust grades. The Guide depicts these conditions after various degrees of wet abrasive blast cleaning, with three levels of flash rusting.