Overview
ISO 8673:2023 specifies requirements for hexagon regular nuts (style 1) with metric fine pitch thread in steel and stainless steel. The standard covers thread sizes 8 mm to 39 mm, and defines product grades A and B, dimensions, tolerances, mechanical requirements, marking and labelling, and designation rules. Nuts larger than 39 mm are addressed informatively in Annex A (historical designs) and are not recommended for new or critical applications.
Key Topics and Technical Requirements
- Scope and materials: Applies to steel and stainless-steel hexagon nuts with fine pitch threads (D×P) from 8 mm to 39 mm; product grade selection (A or B) is specified by size.
- Dimensions and drawings: Detailed dimensional requirements are given (figures and Tables 1–2). Nuts are normally delivered without washer-face unless specified.
- Thread and tolerances: Metric fine pitch threads follow ISO 965-1; standard thread tolerance class 6H is used unless otherwise agreed.
- Mechanical properties:
- Steel nuts: property classes referenced from ISO 898-2 (e.g., classes allowed for size ranges).
- Stainless-steel nuts: grades and property classes referenced from ISO 3506-2 (A2, A4, D4, D6 variants listed for different size ranges).
- Product grades: Typical assignment - product grade A for smaller sizes (≤16 mm) and B for larger sizes (>16 mm), per the standard.
- Surface condition & coatings: Default as-processed for steel and clean & bright for stainless steel. Electroplated or zinc-flake coatings are covered by ISO 4042 and ISO 10683; other finishes by agreement.
- Marking & labelling: On-product marking per ISO 898-2 / ISO 3506-2; package labelling must include reference to ISO 8673, thread size (D×P), property class or stainless grade, finish, manufacturer ID, lot number (ISO 1891-4) and quantity.
- Acceptance & inspection: Acceptance inspection guided by ISO 3269; tolerances by ISO 4759-1; surface discontinuities by ISO 6157-2.
Applications and Who Uses ISO 8673
- Engineers, fastener manufacturers, procurement specialists, and quality managers specifying or sourcing metric fine-pitch hexagon nuts for mechanical assemblies.
- Industries requiring defined mechanical performance, interchangeability and traceability - automotive, machinery, construction equipment, and industrial manufacturing.
- Useful for suppliers preparing technical data sheets, purchasers writing procurement specifications, and labs performing acceptance tests.
Related Standards
Keywords: ISO 8673:2023, hexagon regular nuts, fine pitch thread, metric nuts, fasteners standard, product grade A, product grade B, steel stainless steel, thread sizes 8 mm to 39 mm.
