Overview
EN ISO 10512:2025 - Fasteners - Prevailing torque hexagon nuts - Regular nuts (with non‑metallic insert), with fine pitch thread is a CEN-endorsed international standard that defines the characteristics, dimensions and functional requirements for prevailing-torque hexagon regular nuts with non‑metallic inserts. The standard covers metric fine pitch threads from 8 mm to 39 mm, for steel and stainless steel nuts, and specifies product grades A and B. It was prepared by ISO/TC 2 in cooperation with CEN/TC 185 and published/endorsed in 2025.
Key topics and requirements
- Scope and design principles: Specifies prevailing-torque hexagon regular nuts (with a non‑metallic insert such as polyamide) and clarifies the overall nut height = mmin (ISO 898‑2 / ISO 8673 for style 1) plus the prevailing-torque feature. The insert height (hmax − mmin) is identical across regular, high and thin nuts for a given diameter.
- Dimensions and tolerances: Detailed dimensional tables for sizes M8 to M39 (fine pitch and some non-preferred sizes), with specific tolerances for h and other features. M20×2 was added and several non-preferred sizes (18, 22, 27, 33, 39 mm) are included.
- Materials and property classes: Covers steel (quenched and tempered where required) and stainless steel grades; product grades A (≤16 mm) and B (>16 mm). Reference to applicable property classes in ISO 898‑2 and ISO 3506‑2.
- Functional and acceptance requirements: References ISO 2320 for prevailing-torque functional properties, ISO 3269 for acceptance inspection, and ISO 6157‑2 for surface discontinuities.
- Thread and coating rules: Thread tolerance class 6H (option 6G for coated nuts), general thread rules per ISO 965‑1, and surface/coating options (ISO 4042, ISO 10683). Marking and labelling requirements are included (Clause 6).
Applications and users
EN ISO 10512:2025 is directly applicable to:
- Fastener manufacturers and toolmakers producing prevailing-torque hexagon nuts with non‑metallic inserts.
- Design and mechanical engineers specifying vibration-resistant fasteners in machinery, automotive assemblies, industrial equipment and construction.
- Procurement professionals requiring standardized product grades, sizes and certification details.
- Quality control, test laboratories and inspection bodies performing acceptance testing and functional verification.
Keywords: EN ISO 10512:2025, prevailing torque hexagon nuts, non‑metallic insert, fine pitch thread, metric fine pitch, fastener standard, product grades A and B.
Related standards
For implementation, consult the full EN ISO 10512:2025 document and the referenced ISO standards for detailed dimensional tables, test methods and marking requirements.