This paper describes a research program that was conducted to define natural gas contaminant levels necessary to insure that internal corrosion of compressed natural gas (CNG) cylinders does not constitute a hazard over the lifetimes of the cylinders. Corrosion and stress corrosion cracking (SCC) tests were performed on the cylinder materials most widely used in CNG cylinders in the United States (4130X and 15B30 steels and 6061-T6 aluminum alloy). Tests were conducted in aqueous solutions saturated with varying concentrations of natural gas contaminants. Also, metallurgical analyses of nine used CNG cylinders (eight steel and one aluminum) were performed. Limiting concentrations of hydrogen sulfide (H2S), carbon dioxide (CO2), and other CNG contaminants necessary to prevent internal corrosion of CNG fuel and storage cylinders were defined. This knowledge will minimize potential hazards of using CNG as a vehicle fuel. A gas-quality standard based on program results has been adopted by the National Fire Protection Association.

Subject
Embrittlement, Water, Materials, Cylinders, Partial pressures, Contaminants, Natural gas, Steel, Pitting, Hardness, Heat treatment, Stress corrosion cracking, Types of corrosion
© 1991 Association for Materials Protection and Performance (AMPP). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of AMPP. Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
1991
Association for Materials Protection and Performance (AMPP)
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