ISO 4016:2022

Overview

ISO 4016:2022 - "Fasteners - Hexagon head bolts - Product grade C" specifies the characteristics of steel hexagon head bolts with metric coarse pitch threads M5 to M64 and product grade C. The standard defines dimensional tables, tolerances, mechanical property references and marking/label requirements for partially threaded hexagon head bolts. It is the fifth edition (2022) and replaces ISO 4016:2011 with technical updates to dimensions, head shapes and length rules.

Key topics and requirements

• Scope: Steel hexagon head bolts, metric coarse pitch threads M5–M64, product grade C.
• Dimensions: Detailed dimensional tables (M5–M64) for head size, head height, thread lengths and standard length ranges; permitted head indentation and optional washer-face/underhead junction details.
• Tolerances and threads: Thread tolerance class 8g and reference to ISO 965‑1 for metric thread tolerances.
• Mechanical properties: Property classes for M5 ≤ d ≤ M39 commonly 4.6, 4.8; for d > M39 the property class is “as agreed” (refer to ISO 898‑1 for selecting property classes).
• Material & surface: Material specified as steel; surface/coating options referenced (electroplated per ISO 4042, zinc‑flake per ISO 10683, hot‑dip galvanizing ISO 10684) and rules for “as processed (no coating)”.
• Length rules: Shortest and greatest standard length rules (shortest based on multiples of nominal diameter; greatest ≤ 10·d or 500 mm) are defined.
• Marking & labelling: Clause 6 specifies marking on product and labelling on packages for traceability and conformity.
• References: Links to complementary standards - ISO 888, ISO 4753 (dimensional options/ends), ISO 898‑1 (mechanical properties), ISO 4759‑1 (tolerances), ISO 8992 (general bolt requirements).

Applications and who uses ISO 4016

Practical uses:

• Selecting and specifying hexagon head bolts for machinery, construction, automotive, heavy equipment and general engineering.
• Ensuring interchangeability, consistent quality, and correct fit in bolted joints. Who benefits:
• Fastener manufacturers and heat treaters
• Design and mechanical engineers (specification and part selection)
• Procurement and supply chain professionals (compliance and sourcing)
• Quality inspectors and testing labs (acceptance inspection, marking verification)

Related standards

• ISO 898‑1 - mechanical properties and property classes
• ISO 888, ISO 4753 - nominal lengths and thread/part end options
• ISO 965‑1, ISO 4759‑1 - thread tolerances and product-grade tolerances
• ISO 4018 - fully threaded screws (related product family)

ISO 4016:2022 is essential for anyone needing unambiguous, standardised specifications for metric hexagon head bolts (product grade C) to ensure compatibility, performance and traceability across supply chains. Keywords: ISO 4016, hexagon head bolts, product grade C, metric bolts M5–M64, fastener standards.