20G steel tube is mainly used for manufacturing high pressure and higher parameter boiler pipe fittings, cryogenic section superheater, reheater, economizer and water cooling wall, etc. For example, small diameter pipe with wall temperature ≤500℃ heating surface, water wall pipe and economizer pipe, large diameter pipe with wall temperature ≤450℃ steam pipe, header box (economizer, water wall, low temperature superheater and reheater header box), medium temperature ≤450℃ pipeline accessories, etc. As carbon steel will produce graphitization in long-term operation above 450℃, it is best to limit the maximum long-term service temperature of the pipe as heating surface to below 450℃. In this temperature range, the strength of the steel can meet the requirements of superheater and steam pipeline, and has good anti-oxidation performance, plastic toughness, welding performance and other cold and hot processing performance are very good, widely used. The parts of this steel used in The Iranian furnace (refers to a single set) are water inlet pipe (quantity 28 tons), soda water inlet pipe (20 tons), steam connecting pipe (26 tons), economizer header (8 tons), water-reducing warm water system (5 tons), and the rest are used as flat steel and boom materials (about 86 tons).