Method and apparatus for making fiber conduit

Claim 1

IN THE ART OF MAKING FIBER PIPE AND CONDUIT, THE METHOD OF DRYING THE MOIST FIBROUS TUBE FROM WHICH THE PIPE CONDUIT IS MADE AND WHICH IS PRODUCED BY APPLYING WET PULP ONTO A TUBULAR MANDREL, WHICH METHOD IF CHARACTERIZED BY THE FOLLOWING STEPS: A. INTRODUCING A VAPORIAZBLE LIQUID INTO THE INTERIOR OF THE MANDREL THROUGH AN OPEN END THEREOF; B. SO CONFINING SAID LIQUID IN THE MANDREL THAT A QUANTITY THEROF IS IN ECH END PORTIN OF THE MANDREL; C. SUBJECTING THE MANDREL WITH THE FIBROUS TUBE THEREON TO HEAT TO DRIVE THE MOISTURE FROM THE TUBE AND VAPORIZE THE LIQUID IN THE MANDREL; AND D. AS THE DRYING PROCEEDS KEEPING THE ENTIRE INNER SURFACE OF THE END PORTIONS OF THEMANDREL WET WITH THE VAPORIZABLE LIQUID.