Which load classes can you supply? 2026-10-27

A15 (15 kN), B125 (125 kN), C250 (250 kN), D400 (400 kN), E600 (600 kN) and F900 (900 kN). If you are unsure, tell us where it will be installed and we will advise.

What coating do you offer? 2026-10-27

Black bitumen as standard. Epoxy, powder coating or hot-dip galvanising on request; RAL colours available.

What sizes are available? 2026-10-27

Round clear openings DN300–DN900; square 300×300 to 1,000×1,000 mm; gratings in lengths up to [1,000] mm. Custom sizes to drawing.

How can I be sure the cover is really ductile iron? 2026-10-27

Every heat is spectro-analysed before pouring and recorded against the batch number cast into the cover. The spectrometer printout and the independent load test report from the Cangzhou Institute of Product Quality Supervision and Inspection can be supplied with your shipment. On request we cast tensile test bars from the same heat.

Why ductile iron rather than grey iron, steel or composite? 2026-10-27

Ductile iron has nodular graphite, so it bends and absorbs impact instead of cracking. Against grey iron it gives roughly twice the tensile strength and far higher impact resistance — which is what lets a [40] mm cover take a 400 kN test load. Against steel it does not dent and does not rust through from the inside. Against composite covers it keeps its shape under sustained wheel loads and does not creep on hot asphalt.

What materials do you use? 2026-10-27

All our covers and gratings are cast iron. The standard grade is ductile iron GJS-500-7 (GGG50), equivalent to ASTM A536 65-45-12, with tensile strength ≥ 420 MPa and elongation ≥ 10%. For light-duty A15 and B125 we can cast grey iron GG20/GG25 on request. We do not supply steel, composite or resin covers.

What standards do your products comply with? 2026-10-27

Covers and gratings are manufactured to GB/T 23858-2009, the Chinese national standard whose A15–F900 load classes correspond directly to EN 124. On request we produce to ASTM A536 or the standard of your market.