Import A194 2h / A563 Dh Heavy Hex Nut — Buy in wholesale FOB from Supplier in China

The A194 2H and A563 DH heavy hex nut is a structural fastener designed for high-temperature and high-strength bolting applications, manufactured by Ningbo Gangtong Zheli Fasteners in Zhejiang Province, China. These nuts conform to ASTM A194 Grade 2H (for pressure vessels and valves) and ASTM A563 Grade DH (for structural steel connections), with the heavy hex pattern providing 25% greater bearing surface than standard hex nuts to distribute clamping load. The supplier produces these nuts in carbon steel (low and middle grades), alloy steel, stainless steel, brass and aluminium alloy, with post-production treatments including black oxide, zinc plating, hot-dip galvanising, nickel and chrome plating, and Dacromet for corrosion resistance.

The A194 2H specification requires a medium-carbon or alloy steel nut heat-treated to achieve a minimum Rockwell hardness of 248 HBW and proof load stress of 150 ksi, making it suitable for service temperatures up to 1000°F (538°C). The A563 Grade DH variant is similarly heat-treated but optimised for structural applications with ASTM A325 and A490 bolts, with typical material being medium-carbon steel with manganese addition for through-hardening. The supplier's inventory includes DIN934, DIN6923, DIN1587, DIN928, DIN929 and cage nut variants, indicating broad fastener manufacturing capability rather than single-product specialisation. Standard thread classes for heavy hex nuts are 2B (UNC/UNF) or 6H (metric), with typical width across flats being 1.5 times the nominal diameter plus 1/8 inch for structural sizes.

Buyers for these nuts include petrochemical contractors, power generation equipment fabricators, bridge and steel structure constructors, and valve manufacturers who require traceable ASTM certification. The supplier's location in Ningbo, a major Chinese port city with established fastener manufacturing clusters, offers logistical advantages for sea freight consolidation. Buyers should confirm material certification (MTC with heat number), hardness test reports, and proof load test documentation before placing orders, as the supplier's response rate is currently zero and direct communication is essential to verify current stock levels and exact lead times for specific sizes and finishes.

Ningbo Gangtong Zheli Fasteners Co., Ltd. operates from Jiulong Lake Industrial Zone in Ningbo, Zhejiang Province, China (postal code 315202), a region with dense fastener manufacturing infrastructure and port access through Ningbo-Zhoushan, the world's largest port by throughput. The supplier carries a Harbor trust tier, indicating basic platform verification, though its response rate is recorded at 0.00% with zero average response hours, which suggests either new listing activity, data collection gaps, or operational issues that buyers must investigate directly before relying on email inquiry alone. The company maintains inventory across multiple nut standards (DIN934, DIN6923, DIN1587, DIN928, DIN929, cage nuts) and offers extensive material and coating options, positioning itself as a generalist fastener manufacturer rather than a specialist in high-grade structural nuts.

The supplier's product description emphasises stock availability and custom treatment capability, but provides no information about production capacity, quality management system certification (such as ISO 9001), export experience, or named clients. There is no stated year of establishment, employee count, annual revenue, or factory size in the available profile data. Buyers should request a factory audit or third-party inspection report, verify the supplier's actual production capability for heat-treated heavy hex nuts versus trading activity, and confirm whether the A194 2H and A563 DH production is supported by in-house heat treatment or outsourced to sub-contractors. The listing does not indicate MOQ, sample policy, or standard packing details, all of which require direct clarification.