ISO/TR 25901-1:2016

Overview

ISO/TR 25901-1:2016 - Welding and allied processes - Vocabulary - Part 1: General terms defines the core terminology used across welding and allied processes. This Technical Report provides standardized English, French and Russian terms and definitions for general welding concepts (weld, weld metal, heat‑affected zone, joint types, imperfections, etc.), arranged systematically with an alphabetical index (Annex A). The official terms are also available on the ISO Online Browsing Platform (OBP).

Key topics

ISO/TR 25901-1 organizes and defines essential vocabulary that supports clear technical communication. Major topic areas include:

• General welding terms (welding, fusion welding, weld, weldment, parent material)
• Characterization of welds (weld metal, heat‑affected zone, fusion line, dilution)
• Imperfections and defects (hot cracks, cold cracks, porosity, internal imperfections)
• Types of joints and joint preparations (butt, lap, T‑joint, edge preparation)
• Types of welds and weld details (weld pool, deposited metal, all‑weld metal)
• Welding execution and parameters (manual, mechanized, automatic, welding parameters)
• Surfacing, consumables and materials (filler metals, deposited metal)
• Testing and inspection terminology (weldability tests, mechanical tests, non‑destructive tests)
• Welding equipment, management and personnel terms

Annex A provides an alphabetical index with French translations and German translations (informative, published by DIN). NOTE: only English, French and Russian are official ISO terms.

Practical applications

• Ensures consistent terminology in specifications, welding procedures (WPS), inspection reports, and contracts.
• Helps quality assurance and NDT inspectors interpret and report defects and acceptance criteria unambiguously.
• Supports welding engineers and designers in creating clear documentation and material/joint selection.
• Aids training providers, educators and certification bodies by standardizing teaching material and exam content.
• Useful for technical translators and multinational projects because of multilingual index and formal ISO definitions.

Who should use it

• Welding engineers, inspectors and NDT technicians
• QA/QC managers and manufacturing engineers
• Standards committees, technical authors and specifiers
• Welding educators and vocational trainers
• Procurement and contract specialists in fabrication and construction

Related standards

• ISO/TR 25901 parts on specific processes (Part 3: Welding processes; Part 4: Arc welding)
• Replaces ISO 857‑1:1998 and ISO/TR 25901:2007
• Available on ISO OBP for reference and integration into specifications

Keywords: ISO/TR 25901-1, welding vocabulary, welding terms, weld defects, weld joint types, heat-affected zone, welding standards.