Overview
EN ISO 12671:2021 - “Thermal spraying - Thermally sprayed coatings - Symbolic representation on drawings” (ISO 12671:2021) specifies how thermally sprayed coatings are shown and described on engineering drawings. Published by CEN/ISO in 2021, this standard defines an elementary symbol and supplementary conventions that make coating requirements clear on technical drawings without overloading the document with text or extra views.
Key topics and requirements
- Scope: Defines symbolic representation for thermally sprayed coatings on drawings, including combined (bond/top) coatings and multi-layer builds.
- Elementary symbol: The base symbol TS (thermally sprayed coating) indicates that thermal spraying is the process used.
- Supplementary symbols: Indicate type of coating (BC = bond coat, TC = top coat), spraying process (e.g., APS, PFS or X = free choice), and post‑treatments (f = fused, m/c = machined, s = sealed, as = as sprayed).
- Designation format: Typical sequence - reference to the standard, elementary symbol, supplementary symbol, process, spray material standard, spray material, coating thickness and condition. Example:
- Positioning on drawings: Complete symbol comprises the coating designation (outside the component outline), an arrow line, and a reference line with the elementary symbol placed above it. Reference lines should preferably be parallel to the drawing bottom edge.
- Representation & dimensioning: Coated areas are shown by broad dash-dot lines outside the component outline; permitted coating zones and forbidden zones have distinct line styles; size and tolerances for coating extent and thickness must be dimensioned where necessary.
- Supplementary instructions: If detailed production instructions are required, use a separate parts list or specific technical specification; trade names or patented processes may be referenced as supplementary symbols.
Practical applications
- Ensures consistent, unambiguous communication of coating requirements between designers, manufacturers and quality teams.
- Used for specifying coating type, thickness, spray material, process and post‑treatment on mechanical, construction and manufacturing drawings.
- Helps avoid rework or misinterpretation in repair, surface engineering, and component production where thermally sprayed coatings are applied.
Who should use this standard
- Mechanical/design engineers and drafters producing technical drawings
- Surface‑treatment and coating engineers
- Manufacturing, inspection and quality assurance teams
- Procurement/specification writers and OEMs that require consistent coating documentation
Related standards
Keywords: EN ISO 12671:2021, thermal spraying, thermally sprayed coatings, symbolic representation on drawings, coating designation, coating thickness, spray material, bonding coat, top coat.
