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Tube flanging is the process of crimping the end of a cylindrical metal tube to form a spout shape. Beaded tube ends are commonly used to connect hoses or slide into other metal tubes. Some tube beads are made simply to strengthen and protect the shape of the sheet metal. Metalworkers use internal rolling or ram forming to bend the ends of metal tubes into a bead shape. Many different lengths and diameters of corrugated metal tubing are used in the construction, manufacturing, and automotive industries.
Manufacturers often connect the ends of tubes with beads to create rigid metal shapes. Paired tubes are sized to fit inside one another. The connecting tubes are fitted at their crimped ends to form a comfortable joint. The pressure of the raised edge at the end of the tube holds the joint together. Bolts and welds are often used to secure crimped tube ends for permanent mounting.
Internal rolling lifts the corrugated section by applying pressure from the inside while the tube is held in place. Manual and mechanical devices are used to roll around the diameter of the pipe and create the bead in a relatively slow process. The internal roll forming process is generally used for small-scale accounts and custom pipe accounts. This method of tube flanging is generally considered more accurate. Some heavy gauge metal tubing will not fit internal profiling hand tools.
Ram forming is a faster tube forming procedure that presses internally and externally with a set of punches. Tube ends are formed in a single motion as they are pressed against the carbide punches. Large scale tube flanging is done almost exclusively by the roll forming process. The rapid compaction process flexes the end of the tube, causing the metal to heat up. The beads formed by punches can be slightly irregular or cause slight structural variations in the ends of the tube.
Either style of pipe nipple forms a nipple at the end of a section of metal pipe that is ideal for connecting to a flexible hose. Hoses attached to crimped ends are often clamped in place. Adjustable screw clamps are commonly used to create an airtight and watertight seal between hose and pipe. Polymer adhesives and sealants applied to the crimped ends provide added protection against leaks. If the end of the tube is damaged, it can usually be re-bent to prevent the hose from cracking.