ISO 11124 vs SAE J444: Selecting the Correct Metallic Abrasive Standard for Your Specification
When specifying metallic blast cleaning abrasives, engineers and specification writers face a choice between the international standard (ISO 11124) and the North American SAE standard (SAE J444). Both cover the same abrasive types — cast steel shot, cast steel grit, and chilled iron grit — but use different nomenclature, size designations, and quality requirements.
Understanding the differences is essential for writing clear specifications, qualifying suppliers across different geographic markets, and ensuring the abrasive you purchase meets the quality requirements your project demands.
Overview: The Two Standards
ISO 11124 is published by the International Organization for Standardization under Technical Committee TC 35 (Paints and varnishes). It is the default specification in Europe, the Middle East, Asia, Africa, and Australia. ISO 11124 consists of four parts:
- Part 1: Introduction and classification
- Part 2: Chilled-iron grit
- Part 3: High-carbon cast-steel shot and grit
- Part 4: Low-carbon steel shot
SAE J444 is published by SAE International and is the primary metallic abrasive size standard used in North America. SAE J444 defines only the size designations and sieve requirements. It is supplemented by SAE J827 (high-carbon cast steel shot specification) and SSPC-AB 3 (quality requirements for ferrous metallic abrasive) for a complete specification.
Size Designation Comparison
This is the most immediately apparent difference between the two systems. ISO 11124 uses a metric-based size designation, while SAE J444 uses a legacy code number system:
| SAE Shot Size | Nominal Diameter (mm) | ISO 11124 Nearest Equiv. | Typical Rz Profile (µm) | Application |
|---|---|---|---|---|
| S-780 | 2.00 | — | 90–130 | Heavy castings, rail |
| S-660 | 1.70 | — | 80–120 | Heavy structural, large castings |
| S-550 | 1.40 | — | 70–110 | Heavy structural steel |
| S-460 | 1.18 | — | 60–95 | Structural, pipe |
| S-390 | 1.00 | — | 50–85 | General structural |
| S-330 | 0.85 | — | 45–75 | General industrial |
| S-280 | 0.71 | — | 38–65 | Pipe, pressure vessels |
| S-230 | 0.60 | — | 32–55 | Most common general use |
| S-170 | 0.45 | — | 25–45 | Sheet metal, automotive |
| S-110 | 0.30 | — | 18–32 | Thin sheet, precision |
| SAE Grit Size | ISO 11124 Equiv. | Nominal Sieve Aperture (mm) | Typical Rz Profile (µm) | Application |
|---|---|---|---|---|
| G-10 | CIG/CSG 10 | 2.00 | 100–145 | Very heavy casting cleaning |
| G-16 | CIG/CSG 16 | 1.18 | 85–130 | Heavy castings, thermal spray prep |
| G-18 | CIG/CSG 18 | 1.00 | 75–115 | Thermal spray aluminum (TSA) |
| G-25 | CIG/CSG 25 | 0.85 | 60–95 | Pipeline, marine, offshore |
| G-40 | CIG/CSG 40 | 0.60 | 48–80 | General industrial, bridges |
| G-50 | CIG/CSG 50 | 0.425 | 38–65 | General industrial |
| G-80 | CIG/CSG 80 | 0.212 | 25–45 | Thin coatings, precision |
| G-120 | CIG/CSG 120 | 0.150 | 18–30 | Light coatings, tight profiles |
Hardness Requirements Comparison
Hardness is a critical property that affects abrasive breakdown rate, profile achievability, and in-process performance:
| Abrasive Type | ISO 11124 Hardness | SAE J827 / SSPC-AB 3 | Rockwell Equiv. |
|---|---|---|---|
| High-carbon cast steel shot | 390–530 HV (ISO 11124-3) | 40–51 HRC (SAE J827) | Equivalent ranges |
| High-carbon cast steel grit | 530–700 HV (ISO 11124-3) | 55–62 HRC (SSPC-AB 3) | Equivalent ranges |
| Chilled iron grit | ≥700 HV (ISO 11124-2) | Not in SAE J444 — per SSPC-AB 3: ≥60 HRC | ≥700 HV = ~≥62 HRC |
| Low-carbon steel shot | 80–200 HV (ISO 11124-4) | Not covered by SAE J827 | Very soft, no SAE equiv. |
Defective Particle Requirements
Both systems define maximum allowable percentages of defective particles (voids, cracks, embedded foreign material). ISO 11124-3 via its test methods standard (ISO 11125-5) specifies:
- Maximum defective particles: ≤10% for shot; ≤15% for grit (by mass)
- Defective particles defined as: sponge, hollow shot, fragmented grit, satellites
SAE J827 specifies: maximum 10% defective particles by count for shot.
SSPC-AB 3 adds requirements beyond both SAE J444 and ISO 11124: it specifies maximum conductivity of water extract (≤70 µS/cm for new abrasive), maximum oil content, and visual appearance requirements for delivered abrasive.
Which Standard Should You Specify?
The decision depends primarily on project location, supply chain, and owner requirements:
| Situation | Recommended Standard | Rationale |
|---|---|---|
| North American project, domestic supply | SAE J444 + SAE J827 + SSPC-AB 3 | All North American suppliers certified to these |
| European / Middle East / offshore project | ISO 11124 (relevant parts) + ISO 11125 | ISO is standard in these markets |
| International project, global supply chain | ISO 11124 with SAE J444 cross-reference | Allows maximum supplier flexibility |
| Aerospace / high-precision peening | SAE AMS2431 series | Aerospace-grade additional controls required |
| Foundry wheel blasting, low-carbon shot | ISO 11124-4 | No SAE equivalent for low-carbon grade |
Conductivity / Ionic Contamination Requirements
Neither SAE J444 nor ISO 11124 itself defines a conductivity limit for new abrasive. These limits come from supplementary quality standards and project specifications:
- ISO 11125-6: Defines the test method for conductivity of metallic abrasive water extract (analogous to ASTM D4940 for non-metallics). Typical commercial abrasive: ≤70 µS/cm new, ≤200 µS/cm recycled.
- SSPC-AB 3: ≤70 µS/cm for new ferrous metallic abrasive.
- SSPC-AB 2: ≤1000 µS/cm for recycled metallic abrasive (much looser — oil-free is the primary concern).
- Project specifications for offshore/immersion: Often ≤25–50 µS/cm for new abrasive (stricter than standard references).
Practical Recommendation for Specification Writers
For maximum clarity and global applicability, the following specification language is recommended for international projects:
When referencing both standards, add: "Alternatively, abrasives conforming to SAE J444 / SAE J827 / SSPC-AB 3 with equivalent size designations per the cross-reference table in [Appendix X] are acceptable."
Conclusion
ISO 11124 and SAE J444 + SAE J827 cover the same abrasive types with broadly equivalent technical requirements. The main differences are size designation nomenclature, the inclusion of low-carbon steel shot in ISO 11124 (no SAE equivalent), and the integration of test methods (ISO 11125 vs. SSPC-AB 3 / ASTM B214). For international projects, ISO 11124 with a SAE J444 cross-reference appendix provides the broadest supplier flexibility without compromising quality requirements.