Descaling and corrosion inhibiting method

A process for cleaning and inhibiting scale formation on the surfaces of process equipment which contacts circulating water and/or chemicals, which consists of:

• contacting the process equipment surfaces for a period of about 8 hours and at a temperature of about 300° C. and higher which is effective to effect cleaning and/or scale inhibition with a aqueous composition consisting of:
• a) about 8%, by weight, of hydrochloric acid;
• b) about 1.5%, by weight, of hydrofluoric acid;
• c) a chelating agent which is a mixture of about 2%, by weight, of EDTA and about 2%, by weight, of citric acid;
• d) about 100 ppm of thiourea as a copper complexing agent;
• e) about 40 to about 200 ppm of acridine orange;
• and
• f) optionally a neutral emulsifying agent.