UKC

I recently climbed a sport route at a crag overlooking the Mediterranean.  The bolts on the route were P-shaped glue-ins, which looked like they were in good condition.  At the top of the route were expansion bolts, with hangers and a chain joining them.  The bolts and hangers looked ok, but the chain connecting them was superficially rusted.  There was a "snapgate" lower-off which was very worn, and also bent out of shape.  Three or four maillons had also been attached, at various places (directly to a hanger, halfway down the chain etc.).  Some of these maillons were not fully closed, and at least one looked misshapen.  All of the maillons were heavily rusted, so it wouldn't be possible to tighten them, and a saw would be needed to remove them.

A neighbouring route was bolted with what appeared to be hardware shop-style bolts - instead of a separate nut, the bolts looked like they were a single piece.  I guess this means you have to screw the bolt in with the hangar already present(?)  The heads of these bolts looked very rusty, but the hangers did not.  Overall this didn't inspire confidence.

A few things I'm curious about:

* why would chains rust when the hangers haven't?  I thought these were manufactured as a unit, and presumably from the same grade metal.

* are there climbing-rated bolts with incorporated heads, as opposed to separate nuts that screw on once the bolt has been installed?

* were these maillons the wrong grade of steel?  Does a better type of maillon exist for this environment?  If a fast-rusting maillon is attached to a reliable bolt or hanger, can the maillon negatively affect the reliability of the gear it's fixed to?

* if fixed gear has rusted, would you trust it?

The bits that have rusted are probably galvanised steel, which shouldn't be used at such a location. Depending on the location, even stainless steels can suffer dangerous corrosion, read this: https://www.thebmc.co.uk/bolt-corrosion-warning-from-the-uiaa

Visible rust means some weakening, how much is a bit of a lottery. If the bolts themselves have rusted, be extremely cautious. You can't easily tell how bad it is, but it's usually worst where you can't see.

You might want to have a read of this for more general info: https://www.thebmc.co.uk/bolts-advice-guides

If Jim Titt sees this he may well have some useful stuff to add.

Similar experience here, good looking expansion bolts with a slightly matte looking chain and a superficially rusty maillon at the top out of a couple of routes in Crete. Ended up threading the abseil rope through the maillon and around the chain (not worried about getting the rope stuck as I could have walked around the back to reach the lower off). If that had not been possible, I would have used the maillon. Not too worried about surface rust, it would have to go deep before affecting stability.

CB

There are hundreds of different alloys of steel. Every one will oxidise differently.

All the components should be of the same material however it sometimes isn´t, a well-known Spanish manufacturer has had problems with corrosion on the chains and welded rings. And there is nothing stopping anyone buying hangers and welding a chain into them.

The only certified climbing bolt I can remember which has an internal bolt is the Fixe Triplex bolt but this type are also available from most construction fastening companies, they are particularly popular in the USA where they are generically known as "five piece" bolts, the problem is to buy them in stainless steel as these are relatively rare. There are other "drop-in" anchors where you also only see a bolt head, none of which are certified or any good.

If the rest of the chainset is stainless then the maillons should be the same. A rusting maillon can theoretically effect the part it is fixed to but in reality this is unlikely.

Whether rusting bolts are safe or not is difficult to tell!

Thanks, Jim.  Great info as always, and food for thought.  I'll be steering clear of the heavily rusted stuff for now, and looking into getting some stainless maillons.

On the positive side, last year I encountered a mid 80s lower off on an abandoned project. There were 2 extremely rusty karabiners hanging from a single Petzl hanger that was too old to have any indication of the material (only writing "Petzl" "800 kg"). The hanger was not rusty, even though I suspect it would not, in that era, have been stainless steel of any sort. The nut clean and was easily removed unscrewed from the bolt head and the hanger+ crabs removed. The hole had not been over-drilled so I had to cut off the stub with an angle grinder. At the cut surface there was no sign of corrosion. Obviously I don't know what was going on deeper inside. I think the karabiners had acted as sacrificial anodes. This might also be the case for some chains with rusty maillons etc but I wouldn't like to rely on that except in dire need and with careful testing (e.g. heaviest person down first with backup).