ISO 2553:2019

Overview

ISO 2553:2019 - "Welding and allied processes - Symbolic representation on drawings - Welded joints" defines the rules for using welding symbols on technical drawings to communicate geometry, manufacture, quality and testing requirements for welded joints. The principles also apply to soldered and brazed joints. The standard supports two global symbol systems (suffixes A and B) to reflect different market practices for designating the arrow side and other side on drawings, and it includes an alternative designation method that specifies required weld quality and dimensions while leaving process/joint preparation to production.

Key Topics

• Welding symbol fundamentals: basic and elementary symbols, combinations and supplementary symbols to indicate weld type, extent and special requirements.
• Two symbol systems: System A (dual reference line) and System B (single reference line) - clauses, tables and figures marked “A” or “B” apply only to the respective system; unmarked items apply to both.
• Reference and arrow lines: rules for arrow placement, reference lines, multiple arrows and broken arrow lines to mark weld location.
• Dimensioning rules: cross-sectional and length dimensions for fillet welds, butt welds, plug/slot welds, spot and seam welds, overlays, stud and stake welds; rules for intermittent welds.
• Joint preparation and weld geometry: notation for root gap, included angle, root radius, depth of preparation, countersink angles and other preparation dimensions.
• Supplementary information: weld-all-around, field welds, welds made point-to-point, root reinforcement and flanged joints.
• Alternative designation: method to specify required weld dimensions and quality level while allowing the production unit to select process and joint preparation.
• Informative annexes: practical examples, tolerances and alternative designation methods to aid implementation.

Applications

ISO 2553 is used to:

• Ensure clear, unambiguous welding instructions on engineering and fabrication drawings.
• Standardize communication between designers, welding engineers, production planners, fabricators and inspectors.
• Specify weld type, size, length, quality level and testing requirements directly on drawings.
• Aid in preparing welding procedure specifications (WPS), work schedules and production documents by providing a consistent symbolic language.
• Facilitate international trade and interoperability by reconciling different regional drawing conventions.

Who uses it: mechanical designers, draughtsmen, welding coordinators, QA/QC inspectors, fabricators, shipbuilders and manufacturers working with welded, soldered or brazed assemblies.

Related standards

• ISO 14731 (welding coordination roles and responsibilities)
• ISO 128‑40 (drawing conventions referenced in annexes)
• Relevant WPS and quality standards used in production and testing

Using ISO 2553:2019 helps eliminate ambiguity on technical drawings, improving fabrication accuracy, inspection consistency and cross-border collaboration in welded-assembly projects.