ISO 24373:2018

Overview

ISO 24373:2018 specifies a classification system for solid wires and rods used as welding consumables for fusion welding of copper and copper alloys. The standard classifies filler materials primarily by chemical composition, defines the symbol system for designation, and sets rules for chemical analysis, rounding, retesting and technical delivery. It is intended to help manufacturers, purchasers and welders identify and specify appropriate brazing/filler wires and rods for copper-base materials.

Key Topics

• Scope and purpose: Classification of solid wires and rods for fusion welding of copper and copper alloys based on chemical composition (not mechanical properties of weld metal).
• Symbol system:
  • Product form symbol: S (solid wire/rod).
  • Numerical chemical symbol: numerical codes (see Table 1 in ISO 24373) that correspond to defined alloy chemistries; the chemical symbol may also be used.
  • Use of a Z‑prefix for consumables whose composition is not listed (non‑standard or other compositions).
• Chemical analysis (Clause 7): Analysis shall be performed on product specimens or stock; any analytical technique may be used, with established published methods used in case of dispute.
• Rounding procedure (Clause 8): Test values are rounded following ISO 80000‑1 rules before comparison with classification limits.
• Retest policy (Clause 9): If a test fails, it must be repeated twice and both retests must meet requirements; retests may use original or new samples; only failed elements need retesting for chemical analysis.
• Technical delivery (Clause 10): Delivery conditions reference ISO 544 and ISO 14344 for product types, dimensions, tolerances and procurement.
• Annexes:
  • Annex A: Corresponding national classifications.
  • Annex B: Process considerations (e.g., recommendations for oxyfuel and gas‑shielded metal arc welding).

Applications

ISO 24373 is used to:

• Standardize specification and procurement of copper‑alloy welding consumables across supply chains.
• Guide materials selection for welding procedures and Welding Procedure Specifications (WPS) where filler metallurgy is crucial.
• Support quality control and inspection by providing defined chemical classification and test/retest rules.
• Help manufacturers of filler metals, welding engineers, fabricators, testing laboratories, and OEMs ensure compatibility between filler and base copper alloys.

Practical benefits include clearer communication of filler chemistry, reduced risk of mismatched consumables, and alignment with international procurement and testing practices.

Related Standards

• ISO 544 - Technical delivery conditions for filler materials and fluxes (product types, dimensions, tolerances, markings).
• ISO 14344 - Procurement of filler materials and fluxes.
• ISO 80000‑1 - Quantities and units (rounding rules).
• Historical reference: EN 14640 (original basis for this document).

Keywords: ISO 24373, welding consumables, copper alloys, solid wires, rods, classification, filler metals, chemical composition, welding standards.