Abstract
Traditionally, many firewater mains were made of carbon steel or cast iron. At present, more and more stainless steel is used as material for firewater pipes due to usually better corrosion resistance in natural waters than iron or carbon steel. In some few cases, however, unexpected corrosion failures in systems using austenitic stainless steels were observed only after a relatively short time of usage ranging from a few weeks to a few years. Most of these corrosion damages were found on the weld nuggets or in the heat-affected zones of on-site girth welds. One of the most important factors affecting the corrosion resistance of stainless steel at welds and in heataffected zones are the surface oxide films originating from the welding heat in the presence of oxygen (heat tints). Therefore, proper root shielding is important especially when welding pipes for fire protection systems where the water is taken from natural sources (e.g. from rivers, lakes or tap water), as microbially induced corrosion (MIC) can increase the risk for corrosion damages significantly. Two failure cases in fire protection systems, one in a stainless steel factory and one in a power plant have been studied and are described in this paper. A proposal for the mechanism is suggested and general recommendations how to avoid or diminish the risk for unexpected localised corrosion failures are given.
Original language | English |
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Title of host publication | 6th European stainless steel conference |
Subtitle of host publication | Science and market |
Editors | Pentti Karjalainen, Staffan Hertzman |
Place of Publication | Stockholm |
Publisher | Jernkontoret |
Pages | 129-136 |
ISBN (Print) | 978-91-974131-9-0 |
Publication status | Published - 2008 |
MoE publication type | A4 Article in a conference publication |
Event | 6th European stainless steel conference: Science and market - Helsinki, Finland Duration: 10 Jun 2008 → 13 Jun 2008 |
Conference
Conference | 6th European stainless steel conference |
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Country/Territory | Finland |
City | Helsinki |
Period | 10/06/08 → 13/06/08 |