Hex Head Bushing: A hex bushing is a threaded fitting with a hex head used to tighten the fitting into a threaded opening. Flush Bushing: Flush bushing are used in piping systems. They are installed in the pipe to reduce the size of the pipe. Forged bushing is ideal for use with water and oil in chemical, petrochemical, pulp, paper, shipbuilding, waste incineration, and semiconductor industry applications.