Overview
ISO 7044:2012 specifies the characteristics of prevailing-torque all‑metal hexagon nuts with flange (style 2) for metric threads M5 to M20. It covers product grades A and B (grade A for threads up to and including M16; grade B for threads above M16) and applies to nuts with property classes 8, 9, 10 and 12. This third edition (2012) is a minor revision and references dimensional and performance requirements from existing ISO fastener standards.
Key topics and technical requirements
- Scope and sizing
- Threads covered: M5–M20 inclusive.
- Product grades: A (≤ M16) and B (> M16).
- Property classes: 8, 9, 10, 12.
- Dimensions correspond to ISO 4161 with the added prevailing‑torque feature.
- Materials and tolerances
- Material: steel (general requirements per ISO 8992).
- Thread tolerance class: 6H.
- Mechanical and performance requirements
- Mechanical properties referenced to ISO 898‑2 and prevailing torque performance to ISO 2320.
- Finish and surface integrity
- Gauging and inspection
- Annex A describes a recommended gauging method using two plain ring gauges (A and B) and an additional feeler/ring gauge (C) to verify hexagon height, flange thickness and corner fill.
- Designation
- Example format: Prevailing torque type hexagon nut with flange ISO 7044 - M12 - 8
Applications and who uses this standard
- Typical applications
- Assemblies requiring a self‑locking nut where sustained prevailing torque is needed (machines, automotive subassemblies, industrial equipment).
- Situations calling for flange nuts to distribute load and prevent loosening without separate washers.
- Primary users
- Fastener manufacturers specifying production and inspection criteria.
- Design engineers selecting locking nuts (mechanical, automotive, heavy machinery).
- Procurement/specification writers who need a clear product designation for purchasing.
- Quality/inspection teams using the gauging and acceptance procedures during incoming inspection.
Related standards
Keywords: ISO 7044, prevailing torque nut, all‑metal hexagon nut with flange, flange nut, product grade A, product grade B, M5–M20, property class 8 9 10 12, fastener standards, gauging.