Overview - ISO 8765:2022 (Hexagon head bolts, fine pitch thread)
ISO 8765:2022 specifies the characteristics of hexagon head bolts with metric fine pitch threads in steel and stainless steel, covering thread sizes M8×1 to M64×4 and product grades A and B. The standard defines dimensional data, permissible shapes, lengths, marking and labelling, and designation rules. It is the fourth edition (2022) and replaces the 2011 edition with reorganized tables, added sizes (e.g., M18×2), and extended marking/length rules.
Key topics and technical requirements
- Dimensions and profiles: Dimensional requirements are given graphically (Figures 1–2) and numerically in Tables 1–5; Annex A provides grade B dimensions for 8–14 mm. Symbols and dimension descriptions follow ISO 225.
- Thread range and lengths: Specifies metric fine pitch threads M8×1 to M64×4, rules for shortest/greatest standard lengths and incomplete thread allowances.
- Materials and product grades: Applies to steel and stainless steel bolts in product grades A and B; property classes and stainless grades may be chosen per ISO 898‑1 or ISO 3506‑1 when alternate mechanical requirements are needed.
- Marking and labelling: Clause 6 details mandatory product marking (head marks) and package labelling for traceability and identification.
- Tolerance and acceptance: References tolerances and surface discontinuity/inspection standards (e.g., ISO 4759‑1, ISO 6157, ISO 3269) to define acceptance criteria and quality control practices.
- Designation and reference standards: Clause 7 covers designation; normative references include ISO 262, ISO 888 (lengths), ISO 4753 (chamfer/ends), ISO 965‑1 (thread tolerances), and others.
Applications - who uses ISO 8765 and why
- Fastener manufacturers use the standard to produce hexagon head bolts with repeatable dimensions, head geometry, and correct fine-pitch threads for interchangeability.
- Design and mechanical engineers reference ISO 8765 when specifying bolts for machinery, heavy equipment, industrial assemblies, and other applications requiring fine-pitch threads.
- Purchasing and quality assurance teams use the standard to verify supplied bolts meet required grades, markings, and dimensional tolerances.
- Maintenance and repair technicians rely on standardized sizes and markings to replace fasteners safely and reliably.
- Overall practical benefits: consistent fit and function, simplified procurement, traceability via marking, and clear cross-references to mechanical property standards.
Related standards (useful references)
Keywords: ISO 8765:2022, hexagon head bolts, fine pitch thread, M8×1 to M64×4, product grade A, product grade B, bolt dimensions, marking and labelling, fastener standards.