Sheet Metal Connectors, Inc. spiral pipe is formed from a coil of prime metal into rigid steel tubing with a 4-ply spiral lockseam. It has a smooth interior for low friction loss with the grooved seam entirely on the outside. This HVAC pipe has a resistance to crushing approximately 2 ½ times that of longitudinal lockseam or welded pipe. Optional corrugations are available which increase the rigidity of the pipe by approximately 300%. Pipe sections can be joined together by an E-Z Flange with Barrel Clamp, E-Z Flange Jr. with Barrel Clamp, Complete Seal Connector , Spiral Pipe Connector, or Companion Angle Rings.