This Standard specifies the carbon steel tubes (hereafter referred to as "tubes"）used for pressure service at temperatures up to about 350℃. Tubes for high pressure service shall be in accordance with JIS G 3455. This Standard is applicable to tubes of outside diameters 10.5 mm (nominal diameter 6A or 1/8B) to 660.4 mm (nominal diameter 650A or 26B).