Chrome Moly Alloy Steel
Hot-dip galvanizing forms a comparatively thick zinc coating that protects steel sacrificially and can suit outdoor and industrial exposure. Fasteners are processed as a system: coating thickness, thread accommodation, mating nuts, spinning or centrifuging, and inspection all affect whether the assembled joint works correctly.
ASTM F2329/F2329M addresses hot-dip zinc coating of iron and steel fasteners and covers coating thickness, appearance, adhesion and related requirements. ISO 10684 may apply where an ISO coating system is specified. Use the standard named by the project.
The zinc layer changes pitch diameter. A qualified combination of coated external threads and appropriately accommodated internal threads is essential. Do not mix components from unrelated coating routes without confirming fit, strength and nut compatibility.
Cleaning method, steel hardness, coating temperature and hydrogen-related risk require review for heat-treated bolting. Coating approval must come from the responsible engineer and project specification.
Primary references: ASTM F2329/F2329M and the project-specified edition of ISO 10684.