Seamless steel pipe having exceptional resistance to sulfuric acid dew-point corrosion, and method for manufacturing seamless steel pipe

Abstract

The purpose of the present invention is to provide a seamless steel pipe and a method for manufacturing the same. The present invention is the seamless steel pipe having exceptional resistance to sulfuric acid dew-point corrosion. The seamless steel pipe has a component composition containing, in terms of percentage by mass, 0.02-0.12% of C, 0.010-1.00% of Si, 0.10-2.00% of Mn, no more than 0.050% of P, no more than 0.004% of S, 0.010-0.100% of Al, 0.03-0.80% of Cu, 0.02-0.50% of Ni, 0.55-1.00% of Cr, and 0.005-0.20% of Sb, the remainder comprising Fe and unavoidable impurities. Cu*, Cr*, and Sb* satisfy formula (1): 1.7*Cu* +11*Cr* +3.8 *Sb* >= 13.5, wherein Cu*, Cr*, and Sb* are, respectively, the average Cu concentration (in terms of percentage by mass), the average Cr concentration (in terms of percentage by mass), and the average Sb concentration (in terms of percentage by mass) in a region 0.5-2.0 mm toward the center in the wall thickness direction from the outer surface of the steel pipe. The yield strength of the steel pipe is 230 MPa or greater, and the tensile strength of the steel pipe is 380 MPa or greater.

Description

technical field [0001] The present invention relates to a seamless steel pipe with excellent sulfuric acid dew point corrosion resistance and a method for producing the same. More specifically, the present invention relates to a seamless steel pipe suitable for use in a dew point corrosion environment of sulfuric acid generated in combustion exhaust gas of a boiler, a gasification melting furnace, etc., and particularly to a method for recovering exhaust heat. A seamless steel pipe for piping, which is useful for preventing the scattering of corrosion products caused by sulfuric acid dew point corrosion in boilers, and has excellent sulfuric acid dew point corrosion resistance, and a method for producing the same. Background technique [0002] In the flue of boilers, thermal power plants, etc. that burn fuels such as heavy oil and carbon containing sulfur, sulfur oxides contained in the exhaust gas condense as the temperature decreases to form sulfuric acid, which causes sev...

AI Technical Summary

Problems solved by technology

In particular, although seamless steel pipes are used for the heat recovery piping of the exhaust heat recovery boiler, the life of the piping is shortened and damaged due to the above-mentioned sulfuric acid dew point corrosion. Corrosion products are peeled off and scattered from the exhaust air of the boiler to the surroundings, which may affect the surrounding environment

Images