AS/NZS 1252 High-Strength Structural Bolt Assemblies – M16 to M36, HDG, Class 8.8 (Bolt/Nut/Washer)

This product is a complete high-strength structural bolting assembly manufactured and verified to AS/NZS 1252 . Designed for steel-to-steel connections in building and infrastructure projects, each assembly comprises a property class 8.8 hex head bolt, a property class 8 hex nut, and a hardened washer . Available in diameters from M16 to M36, the assembly features a metric coarse pitch thread and is finished with a hot-dip galvanized (HDG) coating for superior corrosion resistance in external environments

What are the specific mechanical property requirements for the bolt and nut in this assembly?

The bolt is manufactured to property class 8.8, requiring a minimum tensile strength of 800 MPa and a minimum yield strength of 640 MPa . The mating nut is property class 8, with a proof load stress that matches the bolt's minimum tensile strength to ensure thread stripping does not occur before bolt fracture . The washer is through-hardened to a core hardness range of 20 to 45 HRC to properly distribute clamping load under the nut .

How does the "K0" designation affect the traceability and verification of these structural bolts?

The "K0" designation mandates specific third-party verification testing as outlined in AS/NZS 1252.2 . Each bolt head must be permanently marked with three radial lines (positioned at approximately 2, 6, and 10 o'clock), the 8.8 grade marking, the manufacturer's identification mark, and a unique traceability code . This marking system allows full traceability to the specific batch's 3.1 inspection certificate, confirming that the assembly has passed the required proof load and tensile tests .

What are the dimensional and coating requirements for the HDG finish on these assemblies?

The hot-dip galvanized coating is applied to meet the thickness requirements of AS/NZS 4680 . To accommodate this coating thickness, threads are manufactured with an oversize tolerance (6az) before galvanizing, ensuring that after coating the final thread fit mates correctly with the Class 8 nut . The washer features three dimples (nibs) on its outer circumference, which is the distinct identification mark for a hardened structural washer compliant with AS1252 .