ISO 4042:2022

Overview

ISO 4042:2022 - Fasteners - Electroplated coating systems is the international standard that defines requirements, testing and recommendations for electroplated coatings applied to fasteners. It mainly covers steel fasteners (bolts, screws, studs, nuts) and non‑threaded items (washers, pins, clips, rivets), with dimensional requirements extending to copper and copper-alloy fasteners. The standard focuses on corrosion protection and functional coatings - primarily zinc and zinc-alloy systems (zinc, zinc‑nickel, zinc‑iron) and cadmium - and addresses hydrogen embrittlement mitigation, coating build‑up, testing methods and ordering/design considerations.

Key topics and technical requirements

• Scope and precedence: ISO 4042:2022 takes precedence over other electroplating documents when applied to fasteners (see Clause 1).
• Coating systems: Specifies build‑up and permitted combinations - with or without conversion coating, sealant, top coat or lubricant (Clause 4).
• Hydrogen embrittlement: Requirements and recommendations to minimize internal hydrogen embrittlement risk are detailed (Clause 4.4 and Annex B), including baking guidance and special provisions for hardened, case‑hardened and rolled/threaded parts.
• Corrosion testing: Defines corrosion protection testing such as the neutral salt spray (NSS) and sulfur dioxide (Kesternich) tests and links coating performance to test conditions (Clause 5 and Annex E).
• Dimensional and thickness requirements: Rules for coating thickness, gaugeability and assemblability, in particular for ISO metric threads, plus measurement methods (Clause 6 and Annex D). Reference methods include microscopical, coulometric, magnetic and X‑ray spectrometric techniques.
• Quality and testing regime: Specifies mandatory lot testing, in‑process control tests and purchaser‑specified tests (Clause 8).
• Designation, ordering and storage: Provides a designation system for coating systems (Clause 9), ordering requirements (Clause 10) and storage/handling recommendations (Clause 11).
• Design guidance: Annex A supplies design and assembly considerations for joints using coated fasteners.

Practical applications and users

ISO 4042:2022 is essential for:

• Fastener manufacturers and electroplaters ensuring compliant coating processes
• OEMs, automotive, aerospace and industrial procurement teams specifying coated fasteners
• Design and mechanical engineers assessing corrosion protection, assembly torque/clamp behavior and hydrogen embrittlement risk
• Quality managers and test laboratories performing NSS, Kesternich and coating thickness verification
• Maintenance and assembly personnel needing guidance on handling, storage and lubricant/top coat options

Using ISO 4042 helps ensure consistent corrosion protection, dimensional compatibility (gaugeability/assemblability), and reduced failure risk from hydrogen embrittlement - improving reliability across engineered joints.

Related standards (examples)

Normative references cited in ISO 4042 include ISO 1456, ISO 1502, ISO 2082, ISO 3613 and measurement standards such as ISO 1463, ISO 2177, ISO 2178 and ISO 3497 for coating‑thickness determination.