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Common Blast Classes for Protective Coatings

This article gives an overview of the different classes of blast treatment used in Australia, and when they are usually specified. Note that all advice is general in nature, and you should consult an expert before making a decision.

Abrasive Blasting companies in Perth Western Australia include Ferro-Clean

Blast class scales are used to determine the surface preparation level achieved through abrasive blasting. There are two different scales of blast classes, or surface cleanliness standards as they are technically known, commonly used in Australia The first is SSPC Standards or NACE standards, which are not commonly used in Western Australia. The second is ISO standards, which are often used:

  1. The SSPC/NACE Joint Surface Preparation Standard (SSPC/NACE): This standard is widely used in the United States and provides detailed descriptions of different surface preparation levels ranging from SSPC-SP 1, which is a minimum level of surface preparation, to SSPC-SP 10, which is the highest level of surface preparation.
  2. The ISO 8501-1 Standard: This standard is used internationally and provides similar descriptions of surface preparation levels ranging from Sa 1 (Class 1), which is a minimum level of surface preparation, to Sa 3 (Class 3), which is the highest level of surface preparation.

The surface preparation level required for a particular project will depend on factors such as the type of coating to be applied and the environmental conditions the coated surface will be exposed to. Choosing the appropriate blast class scale and achieving the required surface preparation level is important for ensuring the longevity and effectiveness of the coating system.

The details of each of the stages of blast cleaning is listed below.

NACE/SSPC Standard

  • NACE #1 (SSPC-SP 5) – White Metal Blast Cleaning
  • NACE #2 (SSPC-SP 10) – Near-White Metal Blast Cleaning
  • NACE #3 (SSPC-SP 6) – Commercial Blast Cleaning
  • NACE #8 (SSPC-SP 14) – Industrial Blast Cleaning
  • NACE #4 (SSPC-SP 7) – Brush-Off Blast Cleaning

ISO Standard (ISO 8501-1)

  • Class 3 – Blast-Cleaning to Visually Clean Steel
  • Class 2.5 – Very Thorough Blast-Cleaning
  • Class 2 – Thorough Blast-Cleaning
  • Class 1 – Light Blast-Cleaning

While these two standards look similar, they do not align, and often cause confusion. Blast class 2 does not equal NACE #2. They are different standards with their own interpretation. Care should be taken to specify which standard is required.

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