1" HDPE WST1 Socket Tee With the acquisition of Texas-based Independent Pipe Products, Inc. (IPPI), Georg Fischer Central Plastics offers complete, one-stop end-to-end polyethylene piping systems solutions. A global market leader in the supply of pipe and fabricated fittings for imperial piping systems, IPPI’s leading lines of HDPE pipe are available in sizes extending to 65" IPS.