Bolt grades, also called strength classes, indicate a fastener’s tensile and yield strength. Metric grades (e.g., 8.8, 10.9) are marked as two numbers on the bolt head — the first indicates tensile strength in MPa, the second the yield-to-tensile ratio. SAE…

HSFG (High Strength Friction Grip) bolts and regular bolts transfer load differently. HSFG bolts are tightened to a controlled preload, creating clamping friction between joined steel plates so the connection resists slip under service load — making them ideal for bridges,…