Steel Grit for Steel Structures

Shandong Haishan Industrial Technology produces a mixed-grade steel grit specifically for blast cleaning of heavy steel structures. The Steel Grit for Steel Structures combines G40 medium grit as the main fraction with G25 coarse grit to handle thick welding slag and heavy rust. It is designed for use in through-type shot blasting machines and aims to achieve a surface cleanliness of Sa 2.5 in a single pass under typical structural steel workshop conditions.

The manufacturer has an annual production capacity of 100,000 tons and supplies customers in over 50 countries. This product is not intended for thin plates or precision components due to the aggressive cutting profile it creates.

Recommended Blasting Conditions

The mixed G25/G40 formula is selected to match the demands of structural steel components such as H-beams, columns, and bridge sections. The coarse G25 particles provide impact energy to break hard slag and thick scale, while the G40 particles clean remaining rust and tight areas. This combination can reduce the need for a second pass and helps achieve uniform surface preparation.

Typical applications include:

• Pre-treatment of raw H-beams, steel beams, and columns before coating
• Blast cleaning of bridge steel box girders and guardrails
• Batch processing of prefabricated steel structure components
• Sectional rust removal for wind power tower structures
• Renovation cleaning of large factory steel structural parts

Product-Specific Specifications

Hardness is measured on mounted cross-sections using a Rockwell hardness tester. Particle size distribution is verified by sieve analysis according to SAE J444. The mixed grade is specifically prepared for structural steel blasting, not for general abrasive use.

Surface Preparation Performance

Under normal operating conditions, this grit produces a surface profile in the range of 45-70 μm on carbon steel. This anchor pattern is suitable for epoxy zinc-rich primers and other heavy-duty anti-corrosion coatings. The cleanliness level of Sa 2.5 can be reached when blast pressure, nozzle distance, and abrasive feed rate are set correctly. Testing on a small area is recommended before full production to confirm the actual profile depth, as substrate hardness and equipment type may shift the result.

Note: Sa 2.5 refers to the visual cleanliness standard after blasting, not to surface roughness. The two parameters are specified independently in coating requirements.

Compatibility With Blasting Equipment

This mixed grit is suitable for through-type shot blasting machines commonly used in steel structure fabrication. The grain size distribution is designed to flow smoothly through wheel blast systems and air blast nozzles. No special equipment modifications are required when switching from a standard steel grit of similar size. However, separator settings and dust collection should be checked to maintain the desired working mix, as the coarser G25 fraction may settle differently than finer grits.

Quality Control and Testing

Haishan maintains a quality control laboratory equipped with a direct-reading spectrometer, Rockwell hardness tester, metallurgical microscope, and sieve shakers. Every production batch of this mixed grit is tested for chemical composition, hardness, particle size distribution, and microstructure. Test certificates are available with each shipment and include:

• Chemical analysis report
• Hardness test report
• Sieve analysis chart
• Metallographic structure report
• ISO 9001:2015 certificate

Batch traceability is maintained from raw material to final shipment. We have supplied this product to structural steel fabricators in multiple countries.

 

Limitations and Selection Notes

This Steel Grit for Steel Structures is formulated for heavy-duty cleaning of thick steel sections. It creates a relatively rough surface profile, which is beneficial for coating adhesion but may be excessive for thin sheet metal or precision-machined components. Do not use this product on plates thinner than 6 mm or on parts where dimensional tolerance is critical. For such applications, a finer steel grit or a different abrasive type should be selected.

Packaging and Storage

Standard packaging is 25 kg bags with a moisture-resistant PE inner liner and a woven polypropylene outer bag. 1,000 kg bulk bags on pallets are available for large orders. For export shipments, pallets comply with applicable ISPM 15 requirements. Store in a dry, covered area to prevent moisture absorption. The product does not require special pre-treatment before use.

Frequently Asked Questions

Why does this grit use a mix of G25 and G40 sizes?

The G25 coarse particles deliver high impact energy to break heavy welding slag and thick mill scale. The G40 medium particles then clean the remaining rust and reach into corners and weld seams. The combination improves cleaning efficiency in a single pass compared to using either size alone.

Can this grit achieve Sa 2.5 on structural steel?

Yes, under correct blasting parameters (pressure, standoff distance, and feed rate), this product can achieve a Sa 2.5 cleanliness level. We recommend testing on a sample area first, as actual results depend on the initial surface condition and equipment setup.

What surface profile can I expect after blasting?

Typical surface profile is between 45 and 70 μm on carbon steel. The exact value depends on grit hardness, blast pressure, and substrate condition. For coating systems that require a specific profile range, we can adjust the grit mix or suggest alternative parameters.

Is this grit suitable for through-type shot blasting machines?

Yes, the mixed size distribution is designed for through-type machines used in steel structure fabrication. The product flows well and resists bridging in feed hoppers. Check machine separator settings to maintain the correct working mix.

What documentation is provided with each shipment?

Each shipment includes a certificate of analysis showing chemical composition, hardness, and particle size distribution. Additional reports such as metallographic structure and ISO certificates are available on request.

Can this grit be used on thin plates or precision parts?

No, this product is too aggressive for thin materials and may cause deformation or excessive roughness. For plates below 6 mm or precision components, we recommend a finer grit or a different abrasive type.

Page reviewed August 2026. Technical details verified by QC.