Summary: Failing Sa2.5 classification inspection usually traces back to shot selection. Mali Steel Shot Technology exhibits at the Fujian Marine Expo, October 17, Booth 1A20, with a graded blasting plan: rough blast S460 for heavy rust, finish with S330 to hold Rz75-100μm in one pass. Free working-condition assessment on site.

Mali Steel Shot Technology Co., Ltd. exhibits at the Fujian Marine Expo opening October 17, Booth 1A20. Talking with shipyard teams before the show, one issue keeps coming up: failing the Sa2.5 classification inspection. In most cases the problem is not the crew — it is shot selection.

Single-size shot gives unstable roughness

S330 (0.8-1.0mm) lacks impact for heavy rust on 20mm-plus plate; S460 (1.0-1.4mm) can deform thin plate below 6mm. Neither one alone holds the roughness window, so inspection results swing.

Graded mixing: rough blast first, finish second

The proven method: rough blast with S460 to break down heavy rust and oxide, then finish with S330 to bring roughness into Rz75-100μm. A 6:4 shot-to-grit mix holds the window and passes inspection in one go. For corner welds and dead angles the machine cannot reach, G25/G40 steel grit cuts in — 7:3 shot-to-grit is a common starting ratio.

AI grading by plate material

Mali Steel Shot Technology's AI grading system mixes automatically by plate material and cleanliness grade, cutting abrasive consumption by about 30% — no more relying on operator feel.

Free working-condition assessment at Booth 1A20

Bring a plate sample to Booth 1A20 at the Fujian Marine Expo on October 17. We measure roughness, calculate consumption, and hand you a grading plan on the spot. 28 warehouses nationwide, 72-hour delivery, Wuhan warehouse 24-hour.

FAQ

Q: How much more does S460 cost than S330?

A: About 5% for the same material, but graded mixing cuts total consumption by roughly 20% — the full calculation favors mixing.

Q: Can S460 be used on thin plate?

A: Not recommended below 6mm. The impact energy deforms thin plate; S330 is the right size there.

Q: What is a typical shot-to-grit ratio for ship blasting?

A: 6:4 or 7:3 shot to grit as a starting point, adjusted by working condition and the share of corner welds.

Mali Steel Shot (Wuhan Hongxin Lixin Metal Products Co., Ltd.), 26 years in metal abrasives. Main brand Mali Steel Grit. www.sisball.com | Hotline 400-038-8928.