Stress Corrosion Cracking of Pipeline Steels in Fuel Grade Ethanol and Blends

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• Ethanol
• Stress Corrosion Cracking

Main Objective

• Develop and evaluate standardized tests for stress corrosion cracking (SCC) of pipeline steel in ethanol to compliment the slow strain rate tests used in the initial research programs. These standard tests should be reproducible and also be representative of the operating conditions for pipelines
• Develop a phenomenological understanding of stress corrosion cracking of pipeline steel in fuel grade ethanol (FGE)and FGE blends and develop mitigation strategies, including the use of naturally occurring inhibitors, against stress corrosion cracking and corrosion of pipeline steels.

Public Abstract

This project will evaluate and use standard test methods to investigate stress corrosion cracking (SCC)of pipeline steels in fuel grade ethanol(FGE)and gasoline/FGE blends as alternative tests for slow strain rate tests. Although slow strain rate tests (SSRT) can be used as screening tests to understand the environmental conditions that may cause SCC but do not simulate the stress conditions experienced by the operating pipelines. Tapered tensile tests (TTT)will be used to determine threshold stresses needed for SCC initiation under constant loads as well as under fluctuating stresses. Once the threshold stresses under different environmental conditions are determined, 4-point bend (FPB) tests, simulating pipeline stresses will be used to study crack initiation and propagation under different environmental conditions. In both, TTT and FPB tests, original pipeline surfaces can be tested to see the effect of mill scale or used pipeline surface on SCC initiation in FGE environments. Crack growth rate in different environments will be determined by using double cantilever beam (DCB) samples. Role of environmental constituents and impurities in the FGE blends on crack initiation and propagation will be determined by both alternative SCC tests as well as by electrochemical methods to develop phenomenological understanding. SSRT will also be used to compare the data from different test methods and evaluate its effectiveness in predicting SCC behavior in the real pipeline conditions. Ethanol from different sources, including corn, sugarcane, and cellulose based FGE will be tested in this three year project. Two graduate and three undergraduate students will be actively involved in this project. Industrial sponsors including Colonial Pipeline Company, Archer Daniels Midland (ADM), and others industry representatives will serve as advisors on this project.