Wet Abrasive Blast Cleaning Standards Now Available
March 25, 2016
Committee Name: SSPC/NACE Joint Task Groups 350 A, B, C, D, and E and SSPC C.2 Group Committee
Committee Chair Name and Company:
Lydia M. Frenzel, The Advisory Council, Richard A. Burgess, KTA-Tator (vice-chair)
Description of Contents/ Technical Revisions:
These standards combine elements of the existing standards for dry abrasive blast cleaning with elements of the 2012 SSPC/NACE waterjet cleaning standards. The definitions of cleanliness for the steel surface immediately following wet abrasive blast cleaning are identical to the definitions in the five dry abrasive blast cleaning standards. However, because water is used to convey the abrasive onto the surface, a layer of flash rust will form on the cleaned steel as the water evaporates. Due to the varied tolerance of coatings for the presence of flash rust on the surface, it is important that the contractor know the maximum permissible level of flash rust that may be present on the steel immediately prior to the application of the protective coating, and how to assess how much flash rust has developed. The wet abrasive blast cleaning standards define four levels of flash rust: no flash rust, light flash rust; medium flash rust; and heavy flash rust. These definitions are based on the extent to which the flash rust obscures the underlying steel substrate, the ease with which it can be removed by wiping with a cloth, and the amount of material that appears on the cloth after the surface is wiped.
As with the waterjetting standards and the dry abrasive blast cleaning standards, the wet abrasive blast cleaning standards also include information on materials and methods used to perform the cleaning process. For example, the water used must be free of contaminants that would affect the cleanliness of the prepared surface, as well as the functioning of the pumps or other equipment. If the project specification includes specific requirements for non-visible contaminants. the water used for waterjetting must be free of impurities that could prevent the surface from meeting those requirements.
Stakeholders Value Statement (how the standard can be used):
Wet abrasive blast cleaning is primarily specified for suppression of dust in areas that would otherwise be prepared by dry abrasive blast cleaning. An additional benefit of using wet surface preparation methods is that they will reduce the levels of any non-visible water-soluble contaminants, such as soluble salts, that may be present on the surface and adversely affect coating performance
Although the definitions of surface cleanliness immediately prior to coating application are the same when using wet abrasive blast cleaning as they are for the dry abrasive blast cleaning standards, the wet abrasive blast cleaning standards eliminate the need for “customizing” the dry blast cleaning standards to address flash rust levels, and other specialized equipment and procedures that must be used with wet cleaning methods.
Relevant to the following training programs:
SSPC Members can download the standards for free in the SSPC MarketPlace or access it via the SSPC Mobile App. Non-members can purchase the standard via the MarketPlace.