Overview
ISO 4033:2023 specifies the characteristics and requirements for hexagon high nuts (style 2) manufactured in steel and stainless steel with metric coarse pitch threads from M5 to M39. The standard covers product grades A and B, dimensional requirements (including optional washer-face), marking and labelling, and references to related mechanical property standards for selection of property classes and stainless steel grades.
This fourth edition updates and extends the previous edition by adding several sizes (including M7, M18, M22, M27, M33 and M39), clarifying dimensional tolerances, and adding stainless steel nuts and marking/labelling requirements.
Key Topics
- Scope and applicability: Hexagon high nuts (style 2) in steel and stainless steel, metric coarse pitch threads M5–M39; product grades A and B.
- Dimensions: Defined by figures and tables in the standard; nuts can be supplied with or without a washer-face. Symbols and descriptions follow ISO 225.
- Materials and property classes: Steel and stainless steel selection is coordinated with ISO 898-2 (carbon and alloy steel) and ISO 3506-2 (corrosion-resistant stainless steel) when other specifications are requested.
- Tolerances and thread class: Thread tolerances and tolerance class references are provided; general reference to ISO 965-1 and ISO 4759-1 for tolerances and product grades.
- Surface condition and coatings: Guidance on as-processed condition, electroplated coatings (ISO 4042), zinc flake (ISO 10683) and hot-dip galvanizing (ISO 10684); surface discontinuities are addressed per ISO 6157-2.
- Marking and labelling: Product marking and package labelling requirements are specified, including reference to ISO 4033, thread size, material/property class, surface condition, manufacturer identification, lot number and quantity.
- Acceptance: Acceptance inspection guidance references ISO 3269.
Applications
ISO 4033:2023 is intended for manufacturers, distributors, designers and quality engineers who require standardized hexagon high nuts for mechanical assemblies and structural connections. Key practical benefits include:
- Interchangeability: Consistent dimensions and tolerances across suppliers for M5–M39 fasteners.
- Traceability: Mandatory marking and labelling elements support lot identification and quality control.
- Specification clarity: Clear links to ISO 898-2 and ISO 3506-2 for selecting material grades and mechanical properties.
Typical use cases: machinery assembly, structural bolting where higher nut height is required, replacement parts supply, and quality assurance in procurement.
Related Standards
For procurement, manufacturing and compliance teams, ISO 4033:2023 provides the authoritative reference to specify, inspect and label hexagon high nuts (style 2) to ensure compatibility, performance and traceability.
