Douglas fir mixed with galvanizing

[Ms2004life]

Every four months i do a rigging and tree survey for a zipline company and i have noticed a silver grey sap oozing from holes that we drilled for bolts to hold up structures in the trees. I am wondering if anyone can direct me to information or has information on the reaction that saps would have on galvanized steel? There is definitely a reaction i'm wondering about corrosion levels

 

[imagineero]

I don't think you're going to get much info on that mate....
And given the nature of ziplining you really cant afford to take a risk. Did you ever see the south park episode "I never should have gone ziplining?" That was a good episode.

I'm hoping that you've used through bolts for the ziplines, and not just threaded the wire rope through the tree then back around with a couple wire rope grips. If you have used through bolts, it's not a big deal to remove the bolt and do an inspection. I'd be doing some sort of random 10% inspection on bolts as part of the process. Any corosion is going to become evident long before it's a hazard. You've (hopefully) got a 10:1 safety margin at every link in the chain which allows for a lot of wear. If things are going wrong you've got plenty of time for replacement.

In my younger days I had a job working for a company in australia that ran something akin to an outward bound style high and low ropes course. It was pure horse apples but it paid well. We had to do an inspection on all the bolts, wire ropes and rope grabs before every course, and over the few years that I was there I never noticed any corosion. I went back about 10 years later and they were still using all the original gear. Gal hardware/ropes are a lot more forgiving than stainless.

Shaun

 

[Ms2004life]

Cheers shaun, yeah thru bolts all round course, same as structures some 20 metres above the ground with multiple stairways was an eight month build. I have noticed this silver sap for a while but with wind and line bounce the scar mever really heals so the sap is always running and getting worse in some cases. Also some pruned branches have the same sap so it is moving up the tree in the softwood. I am a bit concerned with the acid nature of fir sap mixing with the galv, the lines are really long so checking them is no small task. We are setting up an experimental line today to test for corrosiveness tree climbing and drills mmm not to exciting at least its a two stroke

 

[ch woodchuck]

Evening gents..If your seeing sap flow from ''other''parts of the tree...might be an indication of insect activity.. sequoia pitch moth comes to mind.Maybe this page will help

Why Is My Douglas Fir Weeping Sap? | eHow.com

cheers

 

[imagineero]

I'm not really sure on best practice for cabling, but I remember some old threads about it that were pretty good. Might be worth searching the archives. There was a pretty knowledgeable guy here a few years back who had good advice on getting bolt alignment right and other things.

Shaun

 

[Ms2004life]

The cabling and boltin is all good just the silver sap is of concern will look at the archives though as its all learning. It definitely not insect as we dont really have any of concern and we study the trees quite closely and theres no evidence at all. The silver sap is not in all trees it seems only the ones that are in stress. As betwen the landing and the line and guys there are usually about 7 large rods and bolts in each tree on the course some of the trees are large up 5 foot diameter