Overview
ISO 16433:2006 - Resistance welding - Procedure for seam welding of uncoated and coated low carbon steels specifies requirements and guidance for resistance seam welding of two-sheet assemblies made from uncoated and metallic-coated low carbon steels. The standard applies where the maximum single sheet thickness is 0.4 mm to 3 mm, and covers materials such as uncoated steels, hot‑dip zinc (galvanized/galvannealed), electrolytic zinc/zinc‑iron/zinc‑nickel, aluminium‑coated and zinc‑aluminium coated steels. Organic‑coated or primer‑coated steels are excluded.
Key topics and technical requirements
- Materials and surface condition: Steel must be flat‑rolled and free of contaminants (grease, scale, paint, corrosion). Thin phosphate pre‑treatments and some passivations are allowed with parameter adjustment.
- Process types: Defines continuous‑current and interrupted‑current seam welding and other seam processes (wide/thin wheel, mash, wire, wide‑electrode, foil).
- Component design: Requirements for flange width, electrode access, edge distance and joint geometry to ensure consistent weld formation. Notes on pitch: minimum centre‑to‑centre distance between parallel seams is 16 × sheet thickness (t); for t ≤ 1.5 mm the inter‑weld pitch ≈ 3 × tread width (W).
- Welding equipment and electrodes: Guidance on machine capabilities, electrode materials, dimensions and cooling to suit process and coated surfaces (see Annex A).
- Weldability and qualification: Procedures for weldability assessment and establishing welding parameters (welding lobes, parameter windows).
- Testing and acceptance: Type tests (peel, mechanized peel, pressure, metallurgical assessment), routine tests and quality‑control checks covering weld dimensions, nugget width, failure modes, surface appearance and distortion.
- Non‑conformance: Reclamation procedures for assemblies that do not meet requirements.
Practical applications
ISO 16433 is intended for manufacturers, welding engineers and quality managers involved in:
- Automotive body-panel fabrication and assembly
- Appliance and HVAC sheet‑metal fabrication
- General light‑gauge steel assemblies where continuous or intermittent seam welds are used
The standard helps ensure repeatable seam weld quality on coated and uncoated low carbon steels, improving joint integrity, corrosion protection retention and production efficiency.
Who should use this standard
- Welding engineers and process developers
- Quality assurance and inspection teams
- Equipment manufacturers (seam welding machines and electrodes)
- Design engineers specifying joint geometry and production tolerances
Related standards
Normative references and complementary documents include ISO 669, ISO 10447, ISO 14327, ISO 15609‑5, ISO 15614‑12 and others cited in ISO 16433. Annexes A–C provide equipment guidance, typical welding conditions and applicable steel types.