Manufacture of internal pressure-rupturable seal in thermoplastic tubing

Claim 1

A METHOD FOR FORMING RUPTURABLE SEAL IN FLEXIBLE HET WELDABLE THERMOPLASTIC TUBINGWHICH INCLUDES HOLDING A STRIP OF NORMALLY FLAT RESILIENT SHEET MATERIAL DIFFERENT FROM SAID THERMOPLASTIC AND HAVING A TRANSVERSE DIMENSION GREATER THAN THE INTERNALDIAMETER OF TUBING TO BE SEALED WITH THE LONGITUDINAL EDGES OF SAID STRIP CURLED TOWARD EACH OTHER TO REDUCE THE TRANSVERSE MEASUREMENT BETWEEN SAID LONGITUDINAL EDGES TO A DIMENSION LESS THAN THE INTERNAL DIAMETER OF SAID TUBING, INSERTING THE CURLED STROP LENGTHWISE INTO AN OPEN END OF SAID TUBING, RELEASING SAID STRIP TENDS TO FLATTEN AND THEREBY TO EXPAND THE TRANSVERSE DIMENSION BETWEEN THE LONGITUDINAL EDTES THEREOF FRICTIONALLY TO ENGAGE SAID STRIP WITH THE INNER WALL OF SAID TUBING AND RETAIN SAID STRIP INSAID TUBING, EXTERNALLY APPLYING PRESSURE TO THE WALLS OF SAID TUBING FROM OPPOSITE SIDES THEREOF AT THE POSITION OF SAID STRIP TO FLATTEN SAID TUBING AGAINST SAID STRIP WITH A PORTION OF SAID STRIP EXTENDING INTO SAID TUBING BEYOND THE AREA OF APPLICATION OF THE EXTERNALLY APPLIED PRESSURE, AND HEATING THE FLATEN TUBING TO WELDING TEMPERATURE TO CAUSE THE OPPOSITE INNER WALL PORTIONS OF SAID TUBING TO ADHERE TO THE FACES OF SAID STRIP AGAINST WHICH SAID WALL PORTIONS ARE PRESSED, THEREBY FORMING A SEAL ACROSS SAID TUBING WHICH IS RUPTURABLE BY APPLICATION OF PRESSURE TO A FLUID IN SAID TUBING.

Claim 2

A METHOD FOR FORMING RUPTURABLE SEAL IN FLEXIBLE HET WELDABLE THERMOPLASTIC TUBINGWHICH INCLUDES HOLDING A STRIP OF NORMALLY FLAT RESILIENT SHEET MATERIAL DIFFERENT FROM SAID THERMOPLASTIC AND HAVING A TRANSVERSE DIMENSION GREATER THAN THE INTERNALDIAMETER OF TUBING TO BE SEALED WITH THE LONGITUDINAL EDGES OF SAID STRIP CURLED TOWARD EACH OTHER TO REDUCE THE TRANSVERSE MEASUREMENT BETWEEN SAID LONGITUDINAL EDGES TO A DIMENSION LESS THAN THE INTERNAL DIAMETER OF SAID TUBING, INSERTING THE CURLED STROP LENGTHWISE INTO AN OPEN END OF SAID TUBING, RELEASING SAID STRIP TENDS TO FLATTEN AND THEREBY TO EXPAND THE TRANSVERSE DIMENSION BETWEEN THE LONGITUDINAL EDTES THEREOF FRICTIONALLY TO ENGAGE SAID STRIP WITH THE INNER WALL OF SAID TUBING AND RETAIN SAID STRIP INSAID TUBING, EXTERNALLY APPLYING PRESSURE TO THE WALLS OF SAID TUBING FROM OPPOSITE SIDES THEREOF AT THE POSITION OF SAID STRIP TO FLATTEN SAID TUBING AGAINST SAID STRIP WITH A PORTION OF SAID STRIP EXTENDING INTO SAID TUBING BEYOND THE AREA OF APPLICATION OF THE EXTERNALLY APPLIED PRESSURE, AND HEATING THE FLATEN TUBING TO WELDING TEMPERATURE TO CAUSE THE OPPOSITE INNER WALL PORTIONS OF SAID TUBING TO ADHERE TO THE FACES OF SAID STRIP AGAINST WHICH SAID WALL PORTIONS ARE PRESSED, THEREBY FORMING A SEAL ACROSS SAID TUBING WHICH IS RUPTURABLE BY APPLICATION OF PRESSURE TO A FLUID IN SAID TUBING.