1/4" bolts and hangers

[daniel banquo merrick]

I don't know if any of the SoYo climbers are using 1/4" hangers and anchors but I have been thinking about them and thought I'd share a few thoughts. I think 1/4" anchors have their place as temporary placements on first ascent and as permanent placements on back country climbs that won't see much traffic. A list of a few things:

1) The UIAA requires anchors (hanger and bolt) to withstand 25 kN in shear and 15 kN pull-out without failing. That's 5620 lbs and 3370 lbs for aMerrickans. The UIAA requirement is based on worst case factor 2 fall and rigid belay.

2) The UIAA minimum for cams is 5 kN without damage. 1120 lbs

3) The UIAA minimum for chocks is 2 kN without damage.  450 lbs

4) Measured anchor forces by Petzl with belay device:
                        Fall Factor             Anchor Force
                                0.3                  4 kN
                                0.7                  5 kN
                                1.0                  6 kN

5) I made some hangers out of 1x1x1/8 304 SS. Materials cheap but fabrication takes time.

6) I bought a box of 100 Simpson "Strong-bolt 2" 1/4" 316 SS bolts. Box of 100 cost roughly $100.

7) #5 and #6 above tested together results:
                           Pull out (hanger prying on bolt)               2130 lbs ( 9.5 kN)
                           Shear                                                    2760 lbs (12.3 kN)

In both tests the bolt failed and the hanger suffered minimal damage. Note that the forum sees my eight followed by parentheses as a cool-guy emoticon.

9) Camalots:
                Strength : 
                              [0.3] 8 kN, 1798 lbf
                              [0.4] 10 kN, 2248 lbf
                              [0.5] 12 kN, 2698 lbf
                              [0.75-6] 14 kN, 3147 lbf

10) Stoppers:
                  Strength : 
                              [size 1-2] 2 kN (450 lbf)
                              [size 3] 5 kN (1124 lbf)
                              [size 4-5] 6 kN (1349 lbf)
                              [size 6-12] 10 kN (2248 lbf)


11) My conclusion is that a 1/4" anchor of good quality is better protection than a small cam or any chock.

I think proper 1/4" anchors are OK as permanent protection but the route description should describe the bolts and climbers should trust them about like they should trust a stopper. 1/4" anchors would never be acceptable on anything even close to a sport climb.

[mungeclimber]

11) My conclusion is that a 1/4" anchor of good quality is better protection than a small cam or any chock.

I think proper 1/4" anchors are OK as permanent protection but the route description should describe the bolts and climbers should trust them about like they should trust a stopper. 1/4" anchors would never be acceptable on anything even close to a sport climb.

I doubt you'll get much disagreement from this crew.  However, the chocks rated down to 450lbs are scoped for use in a different primary usage. Chocks of that kind, aren't designed as permanent installations.  They are 'bail' gear as a last ditch option, or are used in aid climbing, or used nominally in free climbing. As such we should be detailed in equivocating between small cams chocks and quarter inchers.

1/4" anchors are stronger than most think they are, but their use must be prescribed by 1)type of rock 2) expected life span and 3) should not be a SPOF placement if using quarter inchers. In other words, if the only gear is bolts in a long pitch, I don't think it should be a recommended practice or even an 'accepted practice' to do quarters for long term 'leave in place'. And last, quarters shouldn't be placed by someone new to the game. Even the slightest margin of error and you reduce that quality hole you pull tested on into a flaring and downward facing hole that bottoms out the bolt.

[John]

Jeez, I didn't know the Stopper and Camalot ratings were that low!

Hmm, temp replacement of 1/4" carbon steel with 1/4" SS? Interesting suggestion. I think there is a 1/4" hardware=death reaction from most folks these days. In the event of updating 1/4 for 1/4 you would still have to drill deeper for the new 2-1/4" since most buttonheads are 1" or 1-1/2". One might say "you might as well drill 3/8in if you need to redrill at all" but the weight difference of a 3/8" hand drilling rig (bolts+hangers+drill bit) is drastically heavier and way less attractive in the backcountry.

I don't understand the mixed materials corrosion issue (stainless and carbon steel combo), so the stainless 1/4" studs sound pretty appealing with those ratings. I used a lot of carbon steel buttonheads with SS hangers in the past and know that corrosion of the bolt will be the issue in the long run. In my old 1/4" replacement experience, old buttonheads have been overall pretty solid with a handful of exceptions. The exceptions do haunt me...

hey the number eight next to a parenthesis does make a smiley!!

[daniel banquo merrick]

you would still have to drill deeper for the new 2-1/4"

The Simpson "Strong-bolt 2" 1/4" 316 SS that I bought only require 1-1/8" embedment which is how I tested them. You could pop out an old split-shank and simply install a 1/4" bolt. No drill required and with a new SS hanger you have an anchor that should last a generation or two.

mixed materials corrosion issue (stainless and carbon steel combo)

The combination of the two roughly means that the carbon steel does all the corrosion for both parts. A not entirely accurate way to picture what happens but close. A CS bolt with a SS hanger will cause the CS bolt to corrode faster than it would with a CS hanger. Not only does the bolt corrode faster but most of it is hidden and the hanger looks great because the CS is protecting it from corrosion.

Another thing to watch for is stress corrosion cracking (SCC) which occurs when there are residual stresses in the SS. Bending SS leaves residual stresses and promotes corrosion. This is one reason I've been making hangers out of angle. If you do bend, use the largest radius you can. SCC and corrosion of SS probably isn't a big concern in most of the Sierra so SCC isn't a big concern to most of us.

One thing to consider is placement in acidic environments. Granite is basically inert so any acids that develop from decaying plant matter or acidic rain will remain. Place anchors where they will stay dry away from any seeps.

[susan]

Let's go replace some hardware. Yup for the end closer parent.
This combo only makes a sad face: 8(

Thanks for all the info Dan, what a resource!

[John]

The Simpson "Strong-bolt 2" 1/4" 316 SS that I bought only require 1-1/8" embedment which is how I tested them. You could pop out an old split-shank and simply install a 1/4" bolt. No drill required and with a new SS hanger you have an anchor that should last a generation or two.

Wouldn't that leave about an inch sticking out?

Bolts of any diameter that stick out past the nut can break a biner if they get lodged in an unfortunate way and loaded on a fall. A 1/4" stud would probably bend but 3/8 will surely break a biner in half.

[daniel banquo merrick]

They are only 1-3/4" long. The hanger is 1/8 plus 1/4 for the washer and nut. That does leave 3/8" plus a bit after tightening. My hangers are so small a biner can't snag on the stub but it would be better to have a deeper hole.

[John]

Well there you go, 1-3/4" is much better than 2+".

I was thinking that the suggestion of replacing old 1/4" carbon steel with 1/4" stainless sounds much more attractive to those who want to update hardware but are turned off to the difficulty of upgrading to 3/8". In the backcountry you don't al have the time to spare.

[daniel banquo merrick]

Sometimes I think we are fundamentally changing the character of old climbs by replacing 1/4" anchors with larger. Certainly old rusty split shanks and Leeper hangers should be replaced but I think replacing 1/4" with 1/4" should be considered - especially if the expected fall factor is 1 or less.

Sort of a historic preservation thing.

[mungeclimber]

Except that a quarter was the adequate protection of the day. Replacing with 3/8 is just replacing with protection of the day, with the benefit of hindsight of how quarters can fail.

[John]

I suppose the biggest flaw with the hardware of the day was that the carbon steel split shafts don't hold up over long periods of time and that is ultimately a materials problem. That and the Leeper recall probably made climbers rethink our hardware standards. If they had used 1/4" wedge bolts as the standard, we (at least I) would perhaps be a little less freaked out about 1/4" hardware. Also, some people don't realize that 1/4" hangers were sold regularly well into the 90's which would make some hanger/bolts only 20 years old. The last SMC stainless hangers were pretty thick and high quality but most of them are pinned to routes with rusting carbon steel bolts.

A separate common hardware of the day ( like as far back as the 40's) were those Star-dryvin pieces of crap and they were often 5/16" or 3/8" so they can't say they weren't willing or able to drill that size of hole back then!

[mungeclimber]

Well said.

[daniel banquo merrick]

I think the climbing community has been irrational about embracing the UIAA standards for all situations. Yes, 25 kN is a good idea sometimes but for most placements it is simply overkill. If a sport climbing bolt is going to take 100's, if not 1000's of falls, 25 kN is a fine idea. A bolt on a remote moderate slab is simply never going to see anything like 25 kN. There is a discussion going on over at MP which has brought up government funded replacement of climbing anchors in Europe. That's just what we need, the rangers overseeing permanent anchors.

Right now the biggest obstacle to putting up new routes with 1/4 anchors is the lack of commercial hangers.

[John]

Dan,
I am intrigued with your comment about retaining the feel of a climb by keeping the 1/4" hardware. I can relate to that when, for example, 30 years of climbers clipped old bolts and therefore had a shared experience but how else?

[daniel banquo merrick]

Climbing a route with 1/4" anchors requires a different commitment. There is a thread going on ST where somebody complains that the bolts found on JT climbs are too scary. The old climbers tell him to suck it up and grow some balls or climb something else. Same idea.