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Hardman Knott
Gym climber
Muir Woods National Monument, Mill Valley, Ca
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Aug 16, 2006 - 09:07pm PT
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Lazide wrote:
I should also note that 316 is better re: corrosion than 304, BUT is still not even remotely suitable for use in high chloride (i.e. sea) installations. All 3xx series SS should be considered unsuitable for marine use, ESPECIALLY when coupled with warm temps.
This was the consensus that inspired me to want to re-bolt the route Nancy at Mickey's;
when Jim Thornburg and Jeff Schoen bolted it, they used 1/2" 316 stainless studs.
I was worried about the possibility of SSC, and those bolts were approx 10 years old at the time.
So when the the time came to chop, I was knott prepared for the effort that would be required
to remove them. If the Hot Tuna bolts were hard to chop, (see above), these were a good deal harder.
In this case it was about 15 minutes per bolt with the sledge. I needed a few rest-days afterward...
In the ensuing months, many more routes were re-bolted, and many SS bolts were chopped,
including a lot of older 3/8" ones. All of the bolts took the usual amount of effort;
it didn't seem to make any difference that they happened to be at a seaside crag.
So with these notes in mind, and the prohibitive cost of the Ti bolts ($15 each)
and the mortar ($28 for approx. 12 holes), I would be inclined to recommend
316 stainless 1/2" studs, unless cost is knott an object. So far, so good!
(the above suggestion is intended strictly for areas where SCC is not an apparent factor)
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lazide
Big Wall climber
Bay Area, CA
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Aug 16, 2006 - 10:00pm PT
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thats Hardman! That is really suprising! Maybe due to the lower average temp of that area compared to other areas (tropics) that have had problems? pitting corrosion does become more likely the hotter it gets (I believe it is non-linear, and there is a lower bound below which it won't occur at all.)
This site has a graph which predicts 316L starts pitting around 15C, which is pretty cold (~60F).
http://www.azom.com/details.asp?articleID=1177
As for SCC I don't know how big a different temp would make. I do know that chemical reaction speed doubles for every 10C of temp increase, so it wouldn't suprise me that thai limestone in ~90F temps all year round have a harder time than schist (what is mickey's again?) at ~60-70F avg.
I wish I could give you a better answer!
BTW, some cool pics when I was trying to find some pitting graphs.
http://www.corrosion-doctors.org/Forms/scc.htm
http://www.corrosion-doctors.org/Localized/Crevice.htm
http://www.corrosion-doctors.org/Localized/Pitting.htm
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Pman
Trad climber
Upstate NY
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Topic Author's Reply - Aug 24, 2006 - 02:54pm PT
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Thanks for the discussion, I've learned some things, but would still like some input on the following:
Thoughts with this scenario-
Carbon Steel Rawl 5 piece 1/2" x 3 1/2" bolts placed with FIXE SS (INOX) hangers. Then add a steel (they're not SS I'm guessing) Mallion Rapid screw links to the hangers to facilitate a rap station (added webbing and rap link details not important here but will be present). Then placing this set up in wet canyon environments made of volcanic rock.
How does the steel/ss/steel (ie. bolt/hanger/screw-link)combination react. Is there a negating or compounding effect at all?
Thanks-
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Brian in SLC
Social climber
Salt Lake City, UT
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Aug 24, 2006 - 05:12pm PT
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Here's a few mix and match:
This is a grade 2 or 5 stud with a stainless hanger at Coopers Rock in West Virginia.
14 year old plus Rawl grade 5 with a stainless SMC hanger (which is hammered flat from repeated falls: first bolt on a steep sports route). S Curve in Big Cottonwood Canyon, Utah.
Petzl long life with a zinc plated rapide at Stone Mountain, in North Carolina.
Good ol' leeper and non stainless bolt, this rig is old. Storm Mountain, Big Cottonwood Canyon, Utah.
Here's a top anchor on a sport route pretty much right out of the water on Kalymnos, Greece. Interesting combo of stainless bolts, stainless hanger, non stainless welded cold shut, and a zinc plated chain with a stainless rapide.
Cheers!
-Brian in SLC
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