SA 2 Abrasive Blasting – Detailed Explanation
According to International Organization for Standardization ISO 8501-1, Sa 2 means Thorough Blast Cleaning.
It is a medium-to-high level surface preparation standard used in industrial painting and coating work.
1️⃣ What is SA 2?
Sa 2 – Thorough Blast Cleaning
In this level:
✔ Almost all rust is removed
✔ Almost all mill scale is removed
✔ Almost all old paint is removed
✔ Surface becomes mostly clean metal
⚠ Very slight stains or shadows may remain, but they must be firmly attached.
2️⃣ Surface Appearance After SA 2
After blasting to SA 2 level:
Surface looks uniform and grey
No visible loose rust
No loose paint or scale
Only slight discoloration allowed
It is cleaner than Sa 1 but not as clean as Sa 2.5.
3️⃣ What is Allowed in SA 2?
Allowed:
Slight rust shadows
Slight staining
Very small tightly bonded particles
Not Allowed:
Loose rust
Loose scale
Loose coating
Oil or grease
4️⃣ Where SA 2 is Used
SA 2 is commonly used for:
Industrial steel structures
Storage tanks
Structural beams
Equipment frames
Indoor pipelines
It is suitable for medium corrosion environments.
5️⃣ Comparison with Other Standards
Standard Cleaning Level Rust Remaining
Sa 1 Light Some visible rust
Sa 2 Thorough Very little rust
Sa 2.5 Near white metal Almost none
6️⃣ Surface Profile Requirement
Surface roughness depends on coating system.
Typical profile:
40–75 microns
Depends on abrasive type (garnet, steel grit)
Correct profile ensures proper coating adhesion.
7️⃣ Equipment Settings for SA 2
Air pressure: 80–100 PSI
Nozzle angle: 45°–90°
Distance: 6–12 inches
Abrasive: Garnet or steel grit
8️⃣ Inspection Criteria
Inspector checks:
✔ Visual cleanliness
✔ No loose material
✔ Proper surface profile
✔ No contamination
✔ Correct environmental conditions
Visual comparison charts are used for inspection.
9️⃣ Why SA 2 is Important
If surface is not properly prepared:
Paint may peel
Coating may fail
Corrosion may return quickly
Proper SA 2 blasting increases coating life and durability.
🔟 Simple Definition (Exam Style)
SA 2 is a thorough abrasive blast cleaning level where almost all rust, mill scale, and coating are removed, and the surface appears mostly clean with only slight staining allowed.