Pipe rolling techniques can produce a variety of shapes including sharp angles, 90 degree bends and even pipe coils. Rolled helical coils have a number of specialized industrial uses.
What Is A Helical Coil?
A helix is the formal scientific term for a spiral configuration. When referring to metal tubing, helical coils are a metal tube that has been bent into a spiral shape. Depending upon the required specifications of the finished product, a helical coil may consist of only one or two spiral turns or may be a series of spirals several feet in length. Copper, steel and aluminum piping can all be formed into helical coils, and each type of metal has its own benefits and drawbacks that make it useful for different applications. The size of piping that can be formed into a helical coil is limited by the available bending dies but is generally less than eight inches in diameter.
Helical Coils and Heat Transfer
Many industrial processes require the heating or cooling of large amounts of liquid or gas. Direct heating elements can be inefficient and even dangerous to use around some substances. Large scale heat exchange units employing coiled piping transfer heat much more efficiently and are safer to use than direct heating elements. Helical coils are effective as heat exchangers because the coils increase the amount of surface area in contact with the substance to be heated or cooled. Additional surface area increases the rate of heat transfer. When used to heat a fluid, a coil is immersed in the fluid and then filled with hot water or steam. The heat from the coil raises the temperature of the surrounding liquid or gas. The cooling process operates in reverse. Cold water or a coolant such as R-12 passes through the coil and removes heat from the liquid. Helical coils used in strong chemical solutions must be coated to prevent corrosion from strong acids and bases, and coils that make direct contact with items that will be consumed by humans or animals must be safe for food contact. Connections between the different components of the heat exchanger must be able to resist the pressure of the fluid inside the coil and must be leak proof to prevent cross-contamination between the coil and the fluid being heated or cooled.
Industrial Uses of Helical Coil Heat Exchangers
Heat exchangers employing helical pipe coils have a number of unique industrial uses. Heat exchangers are used to heat crude petroleum to distill it into its many separate components. Heating can also facilitate mixing and can speed up a chemical reaction between two substances. Heat exchangers are also important when heating and cooling large batches of food products at food processing facilities. The most common uses for helical pipe coils are as cooling and heating elements in air conditioners and heat pumps. In that case, the fluid cooled or heated is air.
Helical coils are often used to replace older types of heat exchange units because of their superior performance and low maintenance. Helical coil units are easier to repair and maintain than many other types of heating units. These factors, plus the unusual shape formed by pipe rolling, make helical coils an ideal component for use in industrial heat transfer units.