The “St” means a general structural carbon steel (that is, plain carbon rather than low alloy) which is not intended to be heat treated (that is, other than the heat treatment which naturally occurs during cool-down from the hot-rolling operation).

DIN 17175 St52.8 seamless boiler tube is widely used in boiler industry, petroleum, chemical industry, chemical fiber, metallurgy, medicine, machinery, paper, heat preservation, refrigeration, mechanical equipment, food, electricity, water, construction, aviation, aerospace, marine, shipbuilding, environmental protection and boiler heat exchangers.

St52.8 seamless tube is specially used as heating surface pipe in low and medium pressure boilers (The working pressure is not higher than 5.88 Mpa and the working temperature is below 450℃.). This seamless boiler pipe can also be used as heating surface pipe, economizer, superheater, reheater and petrochemical industrial pipe for high-pressure boilers (The working pressure is above 9.8 Mpa in general and the working temperature is between 450℃ to 650℃. ).