Method for coating pipe

Claim 1

A CONTINUOUS METHOD OF APPLYING A COATING FOR THE PURPOSE OF PROTECTING A METAL ARTICLE AGAINST CORROSION COMPRISING: (A) CONTINUOUSLY PASSING SAID METAL ARTICLE THROUGH A PLURALITY OF TREATING ZONES COMPRISING THE FOLLOWING SUCCESSIVE STEPS: PREHEATED ARTICLE, SAID COATING COMPRISING AN OXY250-280*F.; (B) APPLYING AT LEAST ONE PROTECTIVE CAOT TO SAID PREHEATED ARTICLE, SAID COATING COMPRISING AN OXYGENATED POLYMER OF 50 TO 100 PARTS BY WEIGHT OF BUTADIENE-1,3 AND ABOUT 50 TO 0 PARTS OF STYRENE, CONTAINING 10 TO 20 WT. PERCENT OXYGEN; (C) EFFECTING PARTIAL CURE OF EACH OF SAID PROTECTIVE COATS BY PASSING SAID FRESHLY COATED ARTICLE THROUGH A HEATING ZONE MAINTAINED AT A TEMPERATURE OF 1200-1600*F. FOR A CONTACT TIME OF 40-120 SEC. SO THAT THE TEMPERATURE OF THE COATED ARTICLE REACHES 400-500*F.; (D) COOLING EACH OF SAID PARTIALLY CURED COATINGS TO 60-150*F. (E) REHEATING SAID COATED ARTICLE TO A TEMPERATURE OF 210-250*F, (F) APPLYING FINAL PROTECTIVE COATS TO SAID REHEATED ARTICLE CONSISTING ESSENTIALLY OF THE SAME COMPOSITION AS SAID FIRST COAT; (G) EFFECTING A COMPLETE CURE OF ALL OF SAID COATS BY PASSING SAID ARTICLE THROUGH A FINAL CURING ZONE; (H) MAINTAINING AN AVERAGE GAS TEMPERATURE IN THE FIRST TWO-THIRDS OF SAID FINAL CURING ZONE OF ABOUT 100*F., AND IN THE FINAL THIRD OF SAID FINAL CURING ZONE OF ABOUT 1300*F., (I) MAINTAINING SAID ARTICLE IN SAID FIRST TWO-THIRDS OF SAID FINAL CURING ZONE FOR ABOUT 32 TO 96 SECONDS AND IN FINAL THIRD OF SAID CURING ZONE FOR ABOUT 32 TO 96 SECONDS SO THAT THE TEMPERATURE OF THE COATED ARTICLE GRADUALLY REACHES 450-550*F., BUT DOES NOT EXCEED, 550*F., (J) AND STORING SAID COATED ARTICLE.