Process for pickling and passivating enclosed structures

Claim 1

THE PROCESS OF PICKLING AND PASSIVATING INTERNAL FERROUS SURFACES OF MASSIVE HOLLOW STRUCTURES COMPRISING INTRODUCING A PICKLING SOLUTION INTO THE STRUCTURE IN AN AMOUNT COMPLETELY TO FILL THE STRUCTURE AND IN A MANNER TO EFFECT SUBSTANTIALLY COMPLETE REMOVAL OF AIR THEREBY TO PROVIDE FOR COMPLETE WETTING OF THE INTERIOR SURFACES OF THE STRUCTURE WITH PICKLING SOLUTION, MAINTAINING THE PICKLING SOLUTION IN CONTACT WITH THE INTERIOR SURFACES FOR A TIME SUFFICIENT TO REMOVE RUST AND CORROSION FROM SAID SURFACES, INTRODUCING RINSING WATER INTO THE STRUCTURE WHILE SIMULTANEOUSLY REMOVING PICKLING SOLUTION, SAID RINSING WATER BEING INTRODUCED AT A RATE AT LEAST AS GREAT AS THE RATE OF REMOVAL OF THE PICKLING SOLUTION WHEREBY THE INTERCHANGE IS EFFECTED WITHOUT EXPOSURE OF THE SURFACES TO AIR, CONTINUING THE INTRODUCTION OF RINSING WATER UNTIL THE WATER ISSUING FROM THE STRUCTURE IS SUBSTANTIALLY NEUTRAL, INTRODUCING A SOLUTION CONTAINING AN AGENT CAPABLE OF FORMING A SOLUBLE COMPLEX WITH IRON, HYDROXIDES REMAINING WITHIN THE STRUCTURE TO REMOVE THE IRON HYDROXIDES FROM THE STRUCTURE BY THE INTRODUCTION OF RINSING WATER FOR DISPLACEMENT OF THE COMPLEXING SOLUTIONS, INTRODUC ING A PASSIVATING AGENT IN SOLUTION INTO THE STRUCTURE FOR REPLACEMENT OF THE RINSING WATER, AND MAINTAINING THE PASSIVATING SOLUTION IN CONTACT WITH THE PICKLED SURFACE UNTIL PASSIVATION IS COMPLETED, ECH OF THE FOREGOING STEPS, WITH THE EXCEPTION OF THE FIRST FILLING OF THE STRUCTURE, BEING CARRIED OUT WITHOUT EXPOSURE OF THE SURFACES TO AIR, DRAINING THE PASSIVATING SOLUTION FROM THE STRUCTURE AND THEN DRYING THE PICKLED AND PASSIVATED SURFACES.