Overview
EN ISO 12474:2010 (ISO 12474:2010) specifies the characteristics of hexagon socket head cap screws with metric fine pitch thread. It covers screws with nominal thread diameters from 8 mm up to 36 mm and applies to product grade A. The standard defines geometry, dimensional data, marking and basic requirements needed for manufacturing, inspection and designation of these fasteners. (Annex A provides approximate masses.)
Key topics and technical requirements
- Scope and sizes: Covers M8 to M36 fine-pitch metric threads; certain sizes (e.g. M42 × 3 from earlier standards) were omitted due to reduced loadability.
- Dimensions and tolerances: Detailed head, socket and shank dimensions are given (Figure 1, Table 1). Thread form and limits reference ISO 261, ISO 965-2 and ISO 965-3.
- Material and mechanical properties: Material/property class guidance references ISO 898-1 for carbon/alloy steels (classes such as 8.8, 10.9, 12.9 where applicable), ISO 3506-1 for stainless steel, and ISO 8839 for non‑ferrous metals. Product grade is A.
- Thread tolerancing: Acceptable tolerance classes and thread quality are specified; e.g., tolerance classes for high-strength bolts are indicated in the standard and referenced documents.
- Surface finish and coatings: Electroplating and plating requirements reference ISO 4042; zinc-flake coatings reference ISO 10683.
- Surface discontinuities and acceptability: Defect limits and acceptance inspection procedures follow ISO 6157 (surface discontinuities) and ISO 3269 (acceptance inspection).
- Designation and marking: Example designation format given (e.g., Hexagon socket head cap screw ISO 12474 - M12 × 1,5 × 80 - 12.9).
- Gauging and socket dimensions: Combined gauging of socket and key dimensions referenced (ISO 23429).
Applications and users
EN ISO 12474:2010 is used by:
- Fastener manufacturers for production and quality control of hexagon socket head cap screws with fine-pitch metric threads.
- Design and mechanical engineers specifying fasteners where fine pitch threads are required for finer adjustment, higher clamping accuracy or specific assembly constraints.
- Purchasing, inspection and maintenance teams ensuring components meet standardized dimensions, mechanical properties and surface treatments.
- Standards bodies and testing laboratories performing conformance checks and acceptance inspections.
Practical value: ensures interchangeability, predictable performance, and compliance with international tolerances and material/property classes for precision assemblies that require fine-pitch socket cap screws.
Related standards
Key normative references used by EN ISO 12474:2010 include: ISO 225, ISO 261, ISO 965-2, ISO 965-3, ISO 898-1, ISO 3506-1, ISO 3269, ISO 4042, ISO 4753, ISO 4759-1, ISO 6157-1/3, ISO 8839, ISO 8992, ISO 10683. These govern thread definitions, mechanical properties, surface treatments, tolerances and inspection.
