ISO 3821:2008 specifies requirements for rubber hoses (including twin hoses) for welding, cutting and allied processes. ISO 3821:2008 specifies requirements for rubber hoses for normal duty of 2 MPa (20 bar) and light duty [limited to hoses for maximum working pressure of 1 MPa (10 bar) and with bore up to and including 6,3 mm]. ISO 3821:2008 applies to hoses operated at temperatures -20 °C to +60 °C and used in: gas welding and cutting; arc welding under the protection of an inert or active gas; processes allied to welding and cutting, in particular, heating, brazing, and metallization. ISO 3821:2008 applies neither to thermoplastics hoses nor to hoses used for high pressure [>0,15 MPa (>1,5 bar)] acetylene.