Solar Fastener Manufacturer — China Stainless Bolts, Nuts & Self-Drilling Screws

Frequently asked questions

• What stainless grade should I order for a coastal solar project?+

  For installations within 5 km of saltwater (Persian Gulf, West African coast, Indonesian archipelago), order SS316 (A4-70) by default — molybdenum content gives meaningfully better pitting resistance against chloride. SS304 (A2-70) is correct for inland and arid sites. Hot-dip galvanized grade 8.8 carbon steel is the right choice only for buried or structural-steel components, not exposed mounting hardware.
• What is the typical MOQ and pricing tier for fasteners?+

  Sample / pilot MOQ: 1,000 pcs per SKU (e.g. M8 x 30 hex bolt SS304). Wholesale tier: 5,000 pcs per SKU. Container tier: 50,000 pcs total mixed SKUs in a 20HQ. Bulk packing is 1,000 pcs / carton (smaller bolts) or 500 pcs / carton (M10+). Cartons are stretch-wrapped onto Euro pallets for sea freight.
• Which DIN / ISO standards do your bolts comply with?+

  Hex bolts: DIN 933 (fully threaded) and DIN 931 (partial thread) per ISO 4017 / 4014. Flange nuts: DIN 6923 / ISO 4161. T-head bolts: DIN 261 / DIN 188. Self-drilling screws: DIN 7504. Hanger bolts: DIN 7997 double-thread. Thread tolerance class 6g, mechanical properties per ISO 3506-1 for stainless or ISO 898-1 for carbon.
• Do you provide torque specifications for solar mounting installation?+

  Yes. We publish recommended torque tables for every bolt size and material grade (see our blog "Torque spec for solar mounting bolt"). As a quick reference: M8 SS304 = 18 N·m, M10 SS304 = 35 N·m, M8 grade 8.8 = 24 N·m. Always cross-check against the rail and clamp manufacturer datasheets; never exceed the lower of the two.
• Can I mix-and-match fastener SKUs in a single container?+

  Yes. A typical solar project container ships 6–12 different SKUs (mid clamps, end clamps, rail splices, T-bolts, self-drilling screws, hanger bolts, ground-screw locknuts). We pre-pack per-SKU cartons and provide a printed pick list per pallet so warehouse receiving and installation are simple. Mixed-SKU containers carry no extra packing fee for orders above 1 container.
• Do you supply mill test reports (MTR) and material traceability?+

  Every shipment ships with an EN 10204 3.1 mill test report listing chemical composition, mechanical properties (tensile, yield, hardness), and heat number per batch. For projects that require it (utility-scale, government tenders) we can also provide a 3.1B inspection certificate signed by our QC manager and a third-party SGS / TÜV witness inspection at extra cost.