What are the two main types of abrasives covered in IS 9954?

Steel shot (spherical particles) and steel grit (angular particles), as per Clause 2.

What is the typical hardness specified for regular grade abrasives?

The regular grade should have a hardness of 40 to 50 HRC as per Table 3.

How is the size of the abrasive specified?

By a size designation number (e.g., S-330 for shot, G-40 for grit) which corresponds to a specific sieve analysis range in Table 1 and Table 2.

What is the soundness test for?

The soundness test (Clause 6) checks for cracks and voids within the abrasive particles to ensure they do not shatter prematurely during use.

IS 9954

: 1981

Steel Abrasives for Blast Cleaning - Specification

CurrentSpecializedSpecificationMaterials Science · Painting, Coatings and Surface Finishing

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This standard specifies the requirements for steel shot and grit abrasives used in blast cleaning operations for surface preparation. It covers material composition, hardness, size grading, shape, soundness, and testing methods to ensure the quality and performance of the abrasive media.

Specifies requirements for steel abrasives (shot and grit) used for blast cleaning of surfaces prior to painting or coating.

Quick Reference Values

Carbon Content Range0.85-1.20 %

Manganese Content Range0.60-1.20 %

Silicon Content (Min)0.40 %

Sulphur and Phosphorus Content (Max each)0.05 %

Regular Grade Hardness40 to 50 HRC

Special Hardness Grade H56 to 62 HRC

Minimum Density7.0 g/cm³

Practical Notes

The choice between shot (round) and grit (angular) depends on the desired surface profile and cleaning action. Shot provides a peening effect, while grit provides an etching effect for better coating adhesion.

Recycling of steel abrasives is common and economical, but it is crucial to monitor the operating mix for size, shape, and contaminants to maintain cleaning efficiency.

Hardness is a critical factor; softer abrasives clean slower but have lower breakdown rates, while harder abrasives clean faster but can be brittle and may cause excessive stress in thin substrates.