Process and apparatus for coating the inside of pipe

Claim 1

A PROCESS FOR THE APPLICATION OF RESIN COATING TO THE INSIDE SURFACE OF PIPE COMPRISING THE STEPS OF: (A) DEPOSITING A CHARGE OF FINELY DIVIDED RESIN POWDER INTO A DUST CHAMBER EQUIPPED WITH A PLURALITY OF AIRJETS AND AN AIR-DUST OUTLET IN THE UPPER REGION THEREOF; (B) SUPPLYING COMPRESSED AIR IN STEADY FLOW THROUGH AT LEAST ONE AIRJET OUTLET LOCATED IN THE LOWER REGION OF SAID DUST CHAMBER AND THROUGH AT LEAST ONE AIRJET OUTLET LOCATED IN THE UPPER REGION OF SAID DUST CHAMBER, THE AIR BEING FED INTO SAID LOWER REGION BEING SUPPLIED AT A PRESSURE OF 10-30 LBS. PER SQUARE INCH AND THE PRESSURE OF SAID AIR BEING FED INTO THE UPPER REGION OF SAID DUST CHAMBER BEING SUPPLIED AT A PRESSURE OF 10-60 LBS. PER SQUARE INCH; (C) SUPPLYING COMPRESSED AIR THROUGH AN AIRJET OUTLET LOCATED IN THE LOWER REGION OF SAID DUST CHAMBER WITH PULSATING FLOW UNDER A PRESSURE OF 10-30 LBS. PER SQUARE INCH; (D) PASSING THE RESULTING CLOUD OF DUST FROM THE UPPER REGION OF SAID DUST CHAMBER INTO A LANCE OF APPROPRIATE LENGTH HAVING AN INNER PASSAGEWAY THERETHROUGH; (E) MAINTAINING SAID PASSAGEWAY AT A TEMPERATURE LESS THAN WILL CAUSE ADHERENCE OF SAID POWDER THERETO; (F) DIRECTING THE RESIN POWDER AFTER IT HAS PASSED THROUGH SAID LANCE ONTO THE WALL OF SAID PIPE; AND (G) MAINTAINING SAID PIPE AT A TEMPERATURE SUITABLE FOR CAUSING SOFTENING AND ADHERENCE OF SAID RESIN TO SAID INNER WALL, SAID RESIN DUST BEING APPLIED TO SAID INSIDE SURFACE OF SAID PIPE, WHILE SAID LANCE IS BEING SHIFTED IN RELATIVE POSITION WITH RESPECT TO SAID PIPE FROM A POSITION IN WHICH SAID LANCE OCCUPIES THE FULL LENGTH OF SAID PIPE TO ANOTHER POSITION IN WHICH SAID LANCE IS COMPLETELY WITHDRAWN FROM SAID PIPE.