ISO 7042:2012

Overview

ISO 7042:2012 defines requirements for prevailing torque type all‑metal hexagon high nuts (self‑locking, all‑metal) with metric threads from M5 to M36. It covers property classes 5, 8, 10 and 12 and specifies product grade A for threads up to and including M16 and grade B for threads above M16. The standard ensures consistent dimensions, mechanical characteristics and acceptance rules for these prevailing‑torque hexagon high nuts used in engineered assemblies.

Key topics and technical requirements

• Thread range and sizing: Threads M5 … M36; most nut dimensions follow ISO 4033 except specific dimensions m and h.
• Property classes: Defined mechanical strength classes - 5, 8, 10, 12 - for specifying performance of the nuts.
• Product grade: Grade A for D ≤ M16 and grade B for D > M16 (tolerance and dimensional grading per ISO 4759-1).
• Thread tolerance: Internal thread tolerance 6H; references to ISO 261 / ISO 724 / ISO 965-2 for metric thread geometry.
• Material and surface integrity: Base material is steel; surface defect limits per ISO 6157‑2.
• Coatings and finishes: Electrolytic coatings (ISO 4042), non‑electrolytic zinc flake (ISO 10683) and hot-dip galvanizing (ISO 10684) referenced for protective finishes - additional finishes by agreement.
• Mechanical/performance references: Mechanical characteristics and performance tied to ISO 898‑2 and ISO 2320 (prevailing torque/self‑locking behavior).
• Acceptance and inspection: Reception control and sampling per ISO 3269.
• Design detail: The prevailing‑torque locking element shape is left to manufacturer discretion; nut designation example: “Écrou hexagonal haut autofreiné ISO 7042 - M12 - 8”.

Applications and who uses this standard

ISO 7042 is used when specifying, manufacturing, testing and procuring prevailing‑torque all‑metal hexagon high nuts for reliable, reusable self‑locking fasteners in:

• Mechanical and structural assemblies
• OEM product design and engineering
• Fastener manufacturers and suppliers
• Quality control, inspection and procurement teams

Specifying ISO 7042 nuts helps ensure interchangeability, consistent locking performance, and compatibility with metric threaded components.

Related standards

• ISO 4033 (hexagon high nut dimensions)
• ISO 261, ISO 724, ISO 965‑2 (metric threads)
• ISO 898‑2, ISO 2320 (mechanical and performance)
• ISO 4042, ISO 10683, ISO 10684 (coatings)
• ISO 4759‑1 (tolerances, grades)
• ISO 6157‑2 (surface defects)
• ISO 3269 (reception inspection)

Keywords: ISO 7042, prevailing torque type, all‑metal hexagon high nuts, property classes 5 8 10 12, M5‑M36, product grade A B, metric self‑locking nuts.