Overview
EN ISO 3821:2019 (Corrected 2021-05) - Gas welding equipment - Rubber hoses for welding, cutting and allied processes - specifies requirements for rubber hoses (including twin hoses) used in gas welding, cutting, arc welding with shielding gases, and allied processes such as heating, brazing and metallization. The standard covers normal duty hoses (maximum working pressure 2 MPa / 20 bar) and light duty hoses (≤ 1 MPa / 10 bar, bores ≤ 6.3 mm) and applies to service temperatures from −20 °C to +60 °C. It excludes thermoplastic hoses and hoses used for high-pressure acetylene (> 0.15 MPa / 1.5 bar) and does not cover hose assemblies (see Related Standards).
Key topics and technical requirements
The standard defines construction, performance and testing requirements including:
- Materials and construction for light, normal and flux fuel gas hoses, and twin hose assemblies
- Dimensions and tolerances (inside/outside diameters, wall thickness, concentricity, cut lengths)
- Type tests and requirements, such as tensile strength, elongation, accelerated ageing, adhesion and hydrostatic tests
- Flexibility at ambient and low temperatures, and resistance to incandescent particles and hot surfaces
- Ozone resistance and specific chemical resistance tests (e.g., acetone/DMF for acetylene hoses, n‑pentane for propane hoses, permeability tests for LPG/propane/natural gas)
- Non‑ignition requirement for oxygen hoses and specific tests for flux fuel gas hoses
- Colour coding, gas identification and marking requirements for safe identification in the field
- Normative test methods summarized in annexes (non‑ignition, n‑pentane resistance, hot particle test, etc.)
Applications
EN ISO 3821 is used to ensure safe, reliable rubber hoses for:
- Gas welding and cutting operations in fabrication shops and construction sites
- Shielded arc welding (MIG/MAG/TIG) where gas supply hoses are required
- Brazing, heating and metallization processes in manufacturing and maintenance
- Equipment selection, supplier specifications and quality control for hose manufacturers and distributors
Who should use this standard?
- Hose manufacturers and product engineers - for design and type testing
- Welding equipment OEMs and system integrators - for component selection
- Procurement and quality assurance teams - to specify compliant hoses
- Test laboratories and conformity assessors - to perform required type tests
- Safety officers and maintenance personnel - to verify correct hose use and marking
Related standards
- ISO 8207 - Hose assemblies for gas welding and cutting (hose assemblies requirements)
- ISO 37 - Rubber - determination of tensile properties (normative reference used in testing)
EN ISO 3821:2019 is essential for ensuring compatible, safe rubber hoses in gas welding systems and for meeting regulatory and procurement specifications.