Summary: On October 10, 2026, CNOOC launched a turbine-and-tower tender for its Shanwei Red Bay IV offshore wind project — 500 MW, 28 units of 18 MW class. Guangdong Energy Group tendered another 1,130 MW in late September. Towers and monopiles are blast-cleaned and coated onshore before they go to sea, so abrasive choice decides whether the line keeps up with the installation window.

Why the offshore wind rush pushes blasting abrasives into the spotlight

On October 10, CNOOC issued its tender for wind turbine generators (tower included) and auxiliary equipment for the Shanwei Red Bay IV offshore wind demonstration project. Planned capacity is 500 MW with 28 units of 18 MW class, in water depths of 34 to 43 meters, roughly 30 km off the northern edge of the wind farm.

Two weeks earlier, Guangdong Energy Group bundled three projects into one tender — Gaolan II, Xuwen Dongyi and Xuwen Yangqian — totaling 1,130 MW. Gaolan II is 500 MW with 36 planned 14 MW turbines; Xuwen Dongyi is 400 MW with 29 units of 14 MW; Xuwen Yangqian is a repowering project that retires 33 turbines of 1.5 MW commissioned back in 2009 and replaces them with 17 units of 13 MW and above.

Every tower, monopile and jacket is prefabricated, blast-cleaned and coated onshore before shipment. The offshore installation window narrows in autumn and winter, which pushes onshore work forward. If the blasting line stalls, coating and shipment queue up behind it.

What makes wind components different from ordinary steel plate

Tower sections are rolled from heavy plate, typically 20 to 40 mm thick per shell. The rust layer and mill scale are heavier than on general-purpose plate.

Surface profile requirements are also specific. Too coarse a profile and the coating cannot wet the surface properly; too fine and adhesion is insufficient, so the coating fails within a few years of service. A common requirement is cleanliness to Sa2.5 with a profile of Rz 75 to 100 μm. That window is narrow, and a single-size abrasive tends to leave some areas too coarse and others too fine.

Outer shell, inner shell and flanges need different mixes

For the outer shell, start with S460 alloy cast steel shot. It has enough impact energy to strip mill scale cleanly, then angular steel grit runs through to develop the profile that the coating needs to key into. A 7:3 shot-to-grit ratio is a common starting point.

The inner shell calls for a different approach. Space is tight, and many spots sit outside the blast wheel's reach. A large particle size will not penetrate those areas and tends to over-blast the edges, so S330 is the safer choice here.

Flange faces are a separate case. They are mating surfaces, so the profile must be finer. Finish with a smaller shot size and keep angular grit away from them, or the scratches will show up during assembly.

Stable profile comes from grading, not from one size

With a single size, the profile tends to drift. Abrasive circulates inside the machine and keeps breaking down, so the particle size distribution shifts on its own.

Our approach is AI-based grading: mix several shot and grit sizes in a ratio calculated from workpiece material, plate thickness, machine model and target profile. On the same blast machine with a graded mix, the profile holds at Sa2.5 with Rz 75 to 100 μm, and the first-pass acceptance rate improves noticeably.

Under our own corporate standard Q/HX 001-2026, non-spherical particles are held below 5 percent, sulfur and phosphorus below 0.03 percent, density at or above 7.4 g/cm³, and cyclic life at 2,200 cycles or more. Those figures decide how fast the abrasive breaks down and how much dust it generates.

Stocking ahead of the installation window is part of the cost

Buyers compare price per tonne, but blasting cost should be measured per tonne consumed. A cheap abrasive breaks down faster and generates more fines, so more material goes in for the same surface area. On a long-run wind tower order, a 30 percent difference in consumption is real money — before counting rework from failed profile checks.

An offshore installation window does not wait. One day of downtime pushes shipment and lifting back by days. We operate 28 warehouse bases across China with 72-hour delivery on standard grades, faster in Hubei and neighboring provinces. S330, S390, S460, S550 and 1.0 cut wire shot are kept in stock, so urgent orders only need sizes and quantities.

Wuhan Hongxin Lixin Metal Products Co., Ltd. (Mali Steel Shot) has produced metallic abrasives for 25 years under the Mali Steel Grit brand, covering alloy steel shot, stainless steel shot, cut wire shot and angular steel grit, certified to GB/T 18838.4, SSPC and ISO 9001. Website: http://www.sisball.com/ . Hotline: 400-038-8928.