Abstract
Ethanol has been used for the last several years as an environmentally friendly alternative to methyl tertbutyl ether (MTBE), which is an oxygenate additive to gasoline, to increase octane levels, and to facilitate the combustion process. Pipelines are, by far, the safest and most efficient method to transport fuel grade ethanol (FGE) from the manufacturing facilities to terminals, where the FGE is blended with the gasoline. Pump stations and terminal facilities have been constructed for or converted to ethanol use in the past 10 years. In response, the stress corrosion cracking (SCC) of carbon steel pipe and the performance of select elastomer seals/gaskets have been studied (in other projects) in FGE. Although many of the issues related to corrosion of carbon steel pipe in ethanol have been resolved in these projects, to address completely the effect of ethanol and gasoline-ethanol blends in pipeline systems, investigation of the effects of ethanol on other components, such as pumps, valves, screens, springs, and metering devices, was required. These components contain different materials and are exposed to different types of loading and environmental conditions.
In a research program, the compatibility of various polymeric materials and ferrous and nonferrous alloys, identified from pump stations and terminal facilities, was evaluated using long-term exposure and slow strain rate (SSR) testing. These materials included various aluminum, stainless steel, nickel, and bronze alloys, as well as two types of fluoroelastomers, nylon, polyetheretherkeytone (PEEK), and nitrile butadiene rubber. The paper discusses the results of the program, as well as provides guidance for identifying and selecting appropriate materials of construction that are exposed to ethanol and ethanol blends that are pumped and stored at pump stations and terminal facilities.
