Overview
ISO 10513:2025 defines the characteristics of prevailing‑torque (all‑metal) hexagon high nuts with fine‑pitch metric threads in steel and stainless steel. The standard covers threads from 8 mm to 39 mm and provides for two product grades (A and B). It clarifies design principles for overall and wrenching heights and the inclusion of the prevailing‑torque feature while noting that certain height tolerances do not follow the ISO IT code system.
Key practical points in the document include:
- Nuts are designed with an overall height hmin = mmin (as referenced in ISO 898-2 and ISO 8674 for style 2) plus the prevailing‑torque feature.
- The tolerance hmax − hmin is established relative to hmin rather than the IT system.
- The wrenching height corresponds to values specified for style 1.
- The prevailing‑torque feature shape is at the manufacturer's discretion within the nut's external hexagon.
Key Topics
- Material scope: Steel and stainless steel, with guidance to select property classes and stainless grades from ISO 898-2 and ISO 3506-2 when needed.
- Thread and size range: Metric fine‑pitch threads covering nominal diameters 8–39 mm; detailed dimensions are provided in the standard (Tables 1 and 2).
- Product grades: Product grade A for smaller sizes and grade B for larger sizes, as specified in the standard.
- Functional and acceptance requirements: References to functional testing (ISO 2320 for prevailing torque steel nuts where applicable), surface integrity (ISO 6157-2), acceptance inspection (ISO 3269) and coating/finish standards (ISO 4042, ISO 10683).
- Marking and labelling: On‑product marking and package labelling follow ISO 898-2 (steel) and ISO 3506-2 (stainless steel). Package labels must include at least the ISO reference, thread size, property class/grade, surface condition, manufacturer ID, lot number and quantity.
Applications
Prevailing‑torque hexagon high nuts specified by ISO 10513:2025 are used where controlled prevailing torque, consistent clamp and part interchangeability are required. Typical application areas include:
- Mechanical assemblies and machinery where vibration resistance and re‑useable locking performance are needed.
- Automotive and transport fastenings requiring fine‑pitch threads and reliable torque behaviour.
- Industrial equipment and bolted joints where specification and traceability (marking/lot identification) are critical.
Benefits for users include predictable torque behaviour, compatibility with established mechanical property standards, and clear designation and labelling for procurement and quality control.
Related Standards
ISO 10513:2025 is intended to be used alongside other International Standards, notably:
For orders requiring deviations or additional finishes, property classes, grades or tests should be agreed between purchaser and supplier and referenced to the appropriate ISO documents.