A variety of austenitic alloys are available for use in flue gas desulfurization (FGD) systems. Alloys with Mo content varying from 2 to 16 percent have been used. The 6% Mo superaustenitic alloys perform significantly better in laboratory tests than 4% Mo stainless steels S31725, S31726 and N08904 and approach the performance of the nickel-base N06625 alloy, but fall short of the performance of the N10276 alloy. This presentation concentrates on one of the 6% Mo superaustenitic stainless steels, the N08367 alloy. The possibility of tailoring the PREN of the 6% Mo alloys is examined and the production of versions of N08367 alloy having guaranteed minimum PREN values is described.

Laboratory corrosion data for N08367 alloy are presented. These data show that N08367 alloy is able to resist corrosion in high-chloride environments at temperatures of 66 to 71 °C and pH levels as low as 2. The corrosion of alloys ranging from S31603 through N08367 to N10276 is shown to be aggravated by the addition of 1,000 ppm thiosulfate to 10,000 ppm chloride water at 66°C. The results of tests of N08367 alloy in a simulated SO2 absorber environment are described.

Fabrication of N08367 alloy for FGD applications is discussed and several FGD applications for N08367 alloy are described.

Overall, the 6% Mo alloys are shown to be cost-effective materials of construction to fill the gap between the 4% Mo austenitic stainless steels and higher-Mo nickel-base alloys.

Subject
Materials, Corrosion resistant alloys, Stainless alloys, Materials performance, Nickel based alloys, Molybdenum alloys, Flue gas desulfurization, Acidity, Pitting, Corrosion resistance, Stainless steel, Alloys, Chlorides
Keywords:
6% Mo Superaustenitic Stainless Steel, Flue Gas Desulfurization (FGD), UNS N08367
© 2000 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).
2000
Association for Materials Protection and Performance (AMPP)
You do not currently have access to this content.