Pena-Plas - Your Total PVC Duct Source Product Benefits Exceptional chemical resistance to a broad spectrum of corrosive fumes, gases and fluids. Seamless, large-diameter extrusions provide consistent surface smoothness, uniformity and dimensional stability. Light weight eases fabrication, handling, and installation- reducing installation costs. Long system service life. Lower overall installed cost. Large Diameter Dimensions Harvel PVC seamless round duct is extruded in 6" through 24" sizes to Iron Pipe Size (IPS) dimensions. Harvel's unique precision extrusion technology produces duct with consistent proportional stability, assuring that the mechanical integrity of the duct remains uniform. Produced in IPS diameters, Harvel PVC Duct piping has large internal flow areas that can easily be adapted to other common IPS PVC fittings, reducing fabrication and installation time. For space considerations in congested areas such as pipe chases, additional ID sizes are available in 7", 9" and 11" diameters. Harvel PVC Duct strictly conforms to the following dimensions: O of R = Out of Roundness Factor at time of extrusion We can also arrange installation of your complete system - from tanks to rooftop exhaust.