Understanding Industrial Surface Preparation: A Guide to NACE and SSPC Standards

In the realm of industrial painting and coating, the adage “Never paint a dirty surface” resonates strongly, emphasizing the critical role of surface preparation. Without proper prep, coatings fail to adhere correctly, leading to system failure. While existing standards from independent oversight agencies like NACE International/Society for Protective Coatings (now merged into AAMP, The Association for Materials Protection and Performance) provide valuable guidance, their differing naming conventions can be puzzling.

Here, we break down these standards, particularly the widely recognized NACE/SSPC Joint Surface Preparation Standards, to clarify and simplify their application:

1. SSPC-SP-1: Solvent Cleaning
   • Intended for steel, this method removes oil, grease, and other soluble contaminants using solvents like steam or emulsifying agents, preparing the steel for painting or coating.
2. SSPC-SP-2: Hand Tool Cleaning
   • Involves using non-power tools to clean steel surfaces, removing all loose contaminants like rust or paint. Adherent materials are those that cannot be removed with a dull putty knife.
3. SSPC-SP-3: Power Tool Cleaning
   • Similar to SP-2 but utilizes power tools, focusing on removing loose contaminants from steel surfaces.
4. NACE No. 1/SSPC-SP-5: White Metal Blast Cleaning
   • Describes thorough cleaning of steel surfaces to a white metal condition using abrasive blast media, free of all foreign matter.
5. NACE No. 3/SSPC-SP-6: Commercial Blast Cleaning
   • Entails cleaning steel surfaces with abrasive blast media. Staining on no more than 33% of each area unit is permissible.
6. NACE No. 4/SSPC-SP-7: Brush-Off Blast Cleaning
   • Specifies requirements for cleaning steel surfaces with abrasive blast media, where tightly adherent materials can remain.
7. NACE No. 2/SSPC-SP-10: Near-White Metal Blast Cleaning
   • Similar to SP-6 but allows staining on only 5% of each area unit.
8. SSPC-SP-11: Power Tool Cleaning to Bare Metal
   • Takes surfaces to bare metal, ensuring a minimum surface profile of 1 mil. Unlike SP-3, it mandates a surface profile.
9. NACE No. 8/SSPC-SP-14: Industrial Blast Cleaning
   • Similar to SP-6 and SP-10 but permits tightly adhering materials and surface stains on 10% of each area unit.
10. SSPC-SP-15: Commercial Grade Power Tool Cleaning
    • Requires surfaces to be taken to bare metal like SP-11, but allows for random staining.
11. SSPC-SP-16: Brush-Off Blast Cleaning of Non-Ferrous Metals
    • Applies to non-ferrous metals, requiring a minimum surface profile of .75 mil and cleanliness verified by visual inspection.

Understanding these standards is crucial for contractors tasked with various coating jobs, whether it’s a highway bridge, steel tank, or brewery floor. Proper substrate preparation according to these guidelines ensures the longevity and effectiveness of the coating applied.