
ASTM A490 Grade 12.9 Bolt for Heavy Steel Bridge Construction. Made per ASTM F3125 A325, Grade 8.8 & 10.9 optional. Alloy steel quenched & tempered for stable tensile strength, anti-breakage under long heavy load. Black oxide for indoor dry workshops; electro galvanized for inland outdoor projects; hot dip galvanized for rainy coastal areas like Nigeria. Metric M12-M36 & imperial 1/2''-1-1/2'' in stock, custom length available. Supporting A563 nuts, flat & spring washers for one-stop purchase. Perfect for H/I beam connection, applicable to factory warehouses, steel bridges, high-rises and municipal infrastructure projects. Each batch with official MTC test report. Complete papers support SONCAP clearance for West African countries. Large spot stock with 7-15 days fast delivery. Neutral OEM packing, mixed sizes order & bulk discount available. Uniform precise threads keep steady clamping force, hard to loosen under cyclic vibration, long service life for main steel structures.