Steve Holtzman wrote: > > To all those who claim that stainless steel doesn't rust, you need to be > aware of several things. First as some people have pointed out, there are > different grades of stainless steel and there ability to stand up to salt > water varies. > > Additionally, ss is susceptible to a type of corrosion called chloride > attack. Any solution that contains high levels of chlorides, is very > corrosive to stainless. Sea water, contains over 20,000 ppm of salt (sodium > chloride) dissolved in it. This is EXTREMELY corrosive and the corrosion > that it causes, produces cracks along the crystal boundaries of the alloy Another point to note about saltwater is that near shore, you get considerable differences in salinity from one place to another. It has to do with the relative depth, tidal patterns and lay of the surrounding land. My telltale on this has been my stainless steel Gerber knife. On some paddling trips, it emerges relatively unscathe. On others it looks like something picked up from the soil in an old rusting junkyard. I have not done this lately but I used to consult a table of relative salinity for the waters around here. It appeared in one of NOAA's book of currents tables. The place of greatest salinity around here was (is still, I guess) in the vicinity of City Island. The waters are relatively shallow, meaning they will suffer the greatest evaporation of water, leaving a greater concentration of salt. They are at the extreme end of the tides coming in from the Atlantic via Long Island Sound, meaning they will have the least amount of water change and exchange. The lay of the land and islands creates pockets that are relatively sheltered from the bigger mass of waters of Long Island Sound, i.e. little lagoons, islands-surrounded batches of water, etc. which tends also to limit the exchange with other water and build up concentration of salt thru evaporation. My conclusion is that the greater salinity there (shown in the tables), probably for the reasons I state above, is a real acid (or should I say chlorine) test for stainless steel as shown in the rusting of my knife. I also have detected differences on the Hudson River which I suspect vary with seasons and wind directions. Seasons?: more fresh water fills the area from the river in the Spring than in the Summer because of snow melt and April rains. Wind directions?: winds from our South and Southeast tends to drive more ocean water into the bays and river bringing in more salt. Some days of paddling on the Hudson, my arms are white with encrusted salt; other days there is barely a spot of white on me. The term in German for stainless is rostfrei, i.e. to be free of rust. It is true under many circumstances but clearly not all. A better term would be rostwiderstandsfahig, i.e rust resistant. ralph diaz -- ----------------------------------------------------------------------- Ralph Diaz . . . Folding Kayaker newsletter PO Box 0754, New York, NY 10024 Tel: 212-724-5069; E-mail: rdiaz_at_ix.netcom.com "Where's your sea kayak?"----"It's in the bag." ----------------------------------------------------------------------- *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************Received on Wed Apr 12 2000 - 06:24:04 PDT
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