Overview
EN ISO 10513:2025 - Fasteners: Prevailing torque hexagon high nuts (all-metal), with fine pitch thread - defines the characteristics, dimensions and requirements for prevailing-torque (all-metal) hexagon high nuts in steel and stainless steel. It covers metric fine-pitch threads from 8 mm to 39 mm, and establishes product grades A and B for different diameter ranges. The standard clarifies design principles (height, wrenching height) and adds marking and labelling requirements.
Key topics and technical requirements
- Scope and geometry
- Applies to high hexagon nuts with an integrated prevailing-torque feature (shape left to manufacturer within hexagon envelope).
- Dimension tables for sizes 8–16 mm (product grade A) and 18–39 mm (product grade B) are provided (see Tables 1 & 2).
- Notes on height: overall height hmin = mmin (per ISO 898‑2 / ISO 8674 style 2) plus prevailing-torque feature; hmax is defined relative to hmin so the h tolerance doesn’t follow the ISO IT system. Wrenching height corresponds to style 1 values.
- Materials and mechanical properties
- Steel and stainless steel options are specified. Property classes and quenching/tempering for steel are referenced to ISO 898‑2.
- Common stainless grades noted (A2, A4, D4, D6); stainless fastener properties referenced to ISO 3506‑2.
- Threads and tolerances
- Metric fine-pitch threads with tolerance class 6H (6G may be specified when coating requires it).
- Thread dimensions and pitches follow ISO 965‑1 and ISO screw-thread conventions.
- Functional & acceptance requirements
- Functional prevailing-torque performance generally referenced to ISO 2320 for steel; for stainless steel, prevailing-torque test methods may be nationally specified and should be agreed between purchaser and supplier.
- Product grades, tolerances and surface discontinuity limits reference ISO 4759‑1, ISO 6157‑2, and ISO 3269 for acceptance inspection.
- Surface condition & coatings
- As-processed (clean/bright), electroplated coatings (ISO 4042), non‑electrolytic zinc flake (ISO 10683) and other finishes are covered or to be agreed.
Applications and who uses this standard
- Engineers and designers specifying self-locking high hex nuts for machinery, automotive, railway, wind energy, and heavy equipment.
- Fastener manufacturers and quality assurance teams producing and inspecting prevailing-torque, fine-pitch nuts.
- Procurement professionals and technical buyers who need standardized product grades, marking and interchangeability.
- Test labs and certification bodies performing acceptance inspection and functional testing.
Related standards (for cross-reference)
Keywords: EN ISO 10513:2025, ISO 10513, prevailing torque hexagon nuts, all-metal high nuts, fine pitch thread, metric fine-pitch, fasteners standard, product grade A, product grade B.
