Engineering Aspects of Using HDPE Pipe for the Refinery Outfalls Running Into the Sea

Nowadays, many refineries are built close to the shorelines due to economical point of view. The operation of refineries requires the cooling system which, in many cases is based on the circulation of the water pumped from the sea into the water intake and distributed to the plants. The circulated water should be led back by a proper outfall system somewhere in the sea where the water depth is deep enough and environmental conditions are fully met. High Density Poly Ethylene (HDPE) pipes are one of the options which can be used as a proper outfall system. The bathymetry of the shoreline and coastal zone, outfall discharge, method of installation both in the sea and the shore area as well as HDPE materials and welding techniques should be considered for the selection of a proper outfall system. Fluid characteristics and hydraulic conditions are other issues which should be checked and controlled. Various loadings should be considered for the mechanical design of the pipeline in the sea. This paper attempts to highlight the main steps required to be taken for the design of an HDPE pipe in the sea. Furthermore, a design flowchart is recommended. At the end, the design of the outfall pipeline of the refineries phases 9 & 10 located in South Pars Field of Persian Gulf is discussed and the results are presented.