Import A325 High Strength Hex Head Bolt — Buy in wholesale FOB from Supplier in China

The A325 high strength hex head bolt from Ningbo Topbolt Metalworks Co., Ltd. is a structural steel fastener intended for steel-to-steel connections in buildings, bridges, and other load-bearing structures. The supplier lists sizes from M4 to M100, covering a broader range than typical A325 production, which historically centres on 1/2 inch to 1-1/2 inch diameters for North American structural applications. Material options include carbon and alloy steel grades with mechanical properties corresponding to property classes 8.8, 10.9, and equivalents, with the actual grade supplied dependent on buyer specification. Surface finishes available include QPQ (quench-polish-quench), passivation, electrophoresis, nickel, and copper plating, with bright silver being the standard colour presentation.

A325 bolts under ASTM A325 (or A325M for metric) are manufactured from medium-carbon or medium-carbon alloy steel, quenched and tempered to achieve minimum tensile strength of 120 ksi (825 MPa) for diameters up to 1 inch, with slightly reduced values for larger diameters. The heavy hex head pattern provides greater bearing surface than standard hex heads, distributing clamping force across wider joint areas. Nuts must be matched to ASTM A194 Grade 2H or ASTM A563 Grade DH for proper strength compatibility, and hardened washers per ASTM F436 are required for proper preload development. The supplier's mention of DIN, ANSI, GB, JIS, BSW, and GOST standards indicates multi-standard manufacturing capability, though buyers should verify which standard governs the specific bolt ordered, as dimensional and mechanical requirements differ significantly between ASTM and DIN specifications.

Primary applications include structural steel framing, bridge construction, transmission towers, and heavy machinery assembly where slip-critical or bearing-type connections are designed per AISC or equivalent codes. The M4-M100 size range from this supplier extends well beyond traditional A325 scope, suggesting the listing may encompass general high-strength hex bolts across multiple standards rather than strict ASTM A325-only product. Buyers should confirm with Ningbo Topbolt Metalworks Co., Ltd. whether the A325 designation refers to ASTM A325 specifically, or is used more broadly to denote high-strength structural bolts, and request the corresponding test reports and certification for the standard actually applied.

Ningbo Topbolt Metalworks Co., Ltd. operates from Jiulong Lake Industrial Zone, Zhenhai, Ningbo, Zhejiang Province, China, postal code 315100. The company holds a harbor trust tier, though like many listings, shows a 0.00 percent response rate with no average response hour data, indicating either new listing status or inactive inquiry management. No information is provided about factory floor space, employee count, years in operation, annual turnover, or export licence details.

The supplier's product profile emphasises custom manufacturing across an exceptionally wide diameter range (M4 to M100) and multiple national standards, with original equipment manufacturing (OEM) explicitly offered. The port of shipment is Ningbo, with export markets listed as global. The breadth of finish options and multi-standard capability suggests a flexible, possibly large-scale fastener operation, but buyers should independently verify production capacity for their specific diameter and grade, quality system certification, and any existing client references in their target market before relying on the listing claims.