In order to avoid the exfoliation of oxide layer on superheater that may affect the safe operation of the unit

a two-stage cleaning process was developed to conduct the chemical cleaning tests for the oxide layer on superheater of the 600 MW level boiler in Taishan power plant.The results showed that

this technology can completely clean the oxide layer.Large amount of insoluble residue depositing inside the U-shape pipes of the heater caused by exfoliation of a great deal of oxide layers did not occur.The metal corrosion rate for pipes of different materials were all below 1.0 g/(m2·h).The cleaning medium A can totally dissolve the oxide layer containing low content of Cr or dissolve 90% of the oxide layer containing high content of Cr.While for the bottom Cr-rich layer in material with high Cr content

the cleaning medium B can totally dissolve it.Additionally

the intergranular corrosion and stress corrosion didn't occur on the austenitic stainless steel of the superheater

which satisfied the cleaning requirements.