Overview
EN ISO 8674:2023 - titled "Fasteners - Hexagon high nuts (style 2), with fine pitch thread (ISO 8674:2023)" - is the CEN-endorsed European adoption of the ISO standard that specifies the characteristics of hexagon high nuts (style 2) in steel and stainless steel. It covers metric fine pitch threads from 8 mm to 39 mm and defines product grades A and B. The standard sets dimensional, material and marking/labeling requirements to ensure interchangeability, quality and traceability of fasteners.
Key topics and technical requirements
- Scope & sizes: Nuts with metric fine-pitch threads D × P in the range M8 to M39 (fine pitch variants included). Dimensions and tolerances are given in figures and tables; nuts are supplied normally without washer-face unless specified.
- Materials & property classes: Applies to steel and stainless steel nuts. Property classes and stainless grades can be chosen per ISO 898-2 (steel) or ISO 3506-2 (stainless steel). Common property classes for nuts include 8, 10 and 12 depending on diameter ranges.
- Mechanical treatment: Specifies quenching and tempering requirements in accordance with ISO 898-2 for steel (QT or NQT as applicable). Stainless steel mechanical grades reference ISO 3506 series.
- Threads & tolerances: Thread tolerance class 6H and references to ISO 965-1 for general purpose metric thread tolerances.
- Surface condition & coatings: As-processed (uncoated) delivery by default; electroplated coatings per ISO 4042 or non‑electrolytically applied zinc‑flake per ISO 10683. Surface discontinuity limits reference ISO 6157-2.
- Inspection & acceptance: Acceptance inspection requirements per ISO 3269; tolerances per ISO 4759-1 (product grades A, B, C).
- Marking & labelling: Product marking follows ISO 898-2 (steel) or ISO 3506-2 (stainless). Package labeling must include ISO 8674 reference, thread size D×P, property class/grade, finish, manufacturer ID, lot number and quantity.
Applications and who uses this standard
- Manufacturers and suppliers of hexagon nuts and fasteners for consistent production and international trade.
- Design and mechanical engineers specifying fine‑pitch hexagon high nuts for machinery, automotive, construction, and equipment requiring precise thread engagement.
- Procurement, quality and inspection teams ensuring incoming nuts meet dimensional, mechanical and marking requirements for assembly and safety-critical applications.
- Standards and compliance officers using EN ISO 8674:2023 to harmonize product specifications across European and international markets.
Example designation (from the standard):
Related standards
Key cross-references: ISO 898-2, ISO 3506-2, ISO 965-1, ISO 225, ISO 8991, ISO 8992, ISO 4759-1, ISO 4042, ISO 10683, ISO 6157-2, ISO 3269, ISO 1891-4.
This standard is essential when specifying or procuring metric fine-pitch hexagon high nuts to ensure interchangeability, traceability and compliance with current European and ISO fastener practices.
