Nowadays, plastic manufacturers are giving more attention to energy consumption than they had historically because of significant increase in energy cost. Amhara pipe factory is one of the largest factories in Ethiopia which produce high density poly ethylene pipe (HDPE) producing different outer diameter. In this pipe factory in the production of high density polyethylene pipe, excess amount of energy is wasted by heating and cooling process without any recovery. In this factory heat exchanger networks represent an important part of the plant structure. The purpose of the networks is to maximize heat recovery, thereby lowering the overall factory costs. Process integration is used to integrate heat within loop to optimize the given process and minimize the heating load and cooling load .In the present study of, heat exchanger network (HEN) is designed by using Aspen energy analyzer V10 software. The network with a ΔT min of 100C is the most optimal where the largest energy savings are obtained with the appropriate use of utilities (Save 82% for hot utilities and 100% for cold utilities compared with the current plant configuration). Percentage reduction in total operating cost is 99.98%. Payback Period for new design is 4.9 years. This saving could be done through a plant revamp, with the addition of two heat exchangers. This improvement in the process associated with this technique is not due to the use of advanced unit operation, but to the generation of heat integration scheme.