GB/T 1228 hex bolts are Chinese standard high-strength bolts with large hexagon heads for steel structures. The grades of these steel structure bolts are 10.9s and 8.8s. High-strength hex bolts are made of high-strength steel and they are commonly used in bridges, the connection of rails, high-pressure equipment, and so on.
link:https://www.synergia.cn/materials/gb-standard-bolts/gb-t-1228-hex-bolts.html