Chemical cleaning of metal surfaces employing steam

Claim 1

THE METHOD OF REMOVING AN ADHERING SUBSTANCE SELECTED FROM THE CLASS CONSISTING OF MILL SCALE AND FLY ASH, FROM THE INNER SURFACE OF A VESSEL ADAPTED TO CONFINE A FLUID AND BEING PROVIDED WITH AT LEAST TWO OPENINGS, AT LEAST ONE OF WHICH SERVES AS AN INLET AND AT LEAST ONE OF WHICH SERVES AS AN EXIT TO PERMIT FORWARD MOVEMENT OF FLUID INTRODUCED INTO THE INLET AND THROUGH THE VESSEL MELTING POINT OF THE WAXY MATERIAL TO FREE THE DIE OF METHOD COMPRISES: CONTACTING SAID ADHERING SUBSTANCE WITH STEAM CONTAINING ENTRAINED THEREIN A SUFFICIENT AMOUNT OF A SOLUBILIZING AGENT FOR ADHERING SCALE SELECTED FROM THE CLASS CONSISTING OF FORMIC ACID, CITRIC ACID, ACETIC ACID, HYDROCHLORIC ACID, NITRIC ACID, ALKYLENE POLYAMINE-CARBOXYLIC ACIDS, THE ANHYDRIDE FORM OF SUCH ACIDS, AND WATER-SOLUBLE ACID SALTS THEREOF AND MIXTURES OF SUCH ACIDS AND SALTS, TO ATTACK AND LOOSEN SAID ADHERING SUBSTANCE, SAID CONTACTING STEAM HAVING A TEMPERATURE ABOVE THE BOILING POINT OF WATER AND BELOW ABOUT 250*F., THE WALLS OF SAID VESSEL BEING AT A TEMPERATURE LOWER THAN THAT OF THE STEAM, AND SAID STEAM CONTACTING SAID ADHERING SUBSTANCE AT SUFFICIENT PRESSURE TO PROVIDE TURBULENT ACTION ADJACENT SAID SURFACE AND A POSITIVE MOVEMENT OF SAID STEAM CONTACTING THE SOLUBILIZING AGENT TO DISLODGE AND CARRY ALONG, DISSOLVED AND SUSPENDED THEREIN, THE DISLODGED SUBSTANCE UNTIL AT LEAST A SUBSTANTIAL PORTION OF SAID ADHERING SUBSTANCE IS DISLODGED AND REMOVED FROM THE VESSEL.

Claim 2

THE METHOD OF REMOVING AN ADHERING SUBSTANCE SELECTED FROM THE CLASS CONSISTING OF MILL SCALE AND FLY ASH, FROM THE INNER SURFACE OF A VESSEL ADAPTED TO CONFINE A FLUID AND BEING PROVIDED WITH AT LEAST TWO OPENINGS, AT LEAST ONE OF WHICH SERVES AS AN INLET AND AT LEAST ONE OF WHICH SERVES AS AN EXIT TO PERMIT FORWARD MOVEMENT OF FLUID INTRODUCED INTO THE INLET AND THROUGH THE VESSEL MELTING POINT OF THE WAXY MATERIAL TO FREE THE DIE OF METHOD COMPRISES: CONTACTING SAID ADHERING SUBSTANCE WITH STEAM CONTAINING ENTRAINED THEREIN A SUFFICIENT AMOUNT OF A SOLUBILIZING AGENT FOR ADHERING SCALE SELECTED FROM THE CLASS CONSISTING OF FORMIC ACID, CITRIC ACID, ACETIC ACID, HYDROCHLORIC ACID, NITRIC ACID, ALKYLENE POLYAMINE-CARBOXYLIC ACIDS, THE ANHYDRIDE FORM OF SUCH ACIDS, AND WATER-SOLUBLE ACID SALTS THEREOF AND MIXTURES OF SUCH ACIDS AND SALTS, TO ATTACK AND LOOSEN SAID ADHERING SUBSTANCE, SAID CONTACTING STEAM HAVING A TEMPERATURE ABOVE THE BOILING POINT OF WATER AND BELOW ABOUT 250*F., THE WALLS OF SAID VESSEL BEING AT A TEMPERATURE LOWER THAN THAT OF THE STEAM, AND SAID STEAM CONTACTING SAID ADHERING SUBSTANCE AT SUFFICIENT PRESSURE TO PROVIDE TURBULENT ACTION ADJACENT SAID SURFACE AND A POSITIVE MOVEMENT OF SAID STEAM CONTACTING THE SOLUBILIZING AGENT TO DISLODGE AND CARRY ALONG, DISSOLVED AND SUSPENDED THEREIN, THE DISLODGED SUBSTANCE UNTIL AT LEAST A SUBSTANTIAL PORTION OF SAID ADHERING SUBSTANCE IS DISLODGED AND REMOVED FROM THE VESSEL.