Joe Kinder's honest confession provides the perfect catalyst to take a look at the bolts we use at the North Rim. As climbers, we all tend to see a bolt (or most any piece of fixed gear) as bomber pro and clip in without much thought. But taking the time to examine and question that piece of hardware on which our safety depends is both reasonable and prudent.
There are two reasons to discuss our choices of bolts in putting up routes at the North Rim (and Lolo and Rattler): (1) If you’re planning to bolt a route yourself, the following information may be of use to you. (2) If you’re climbing at the North Rim you might want to know what you’re getting yourself into when you fall. Here are the choices we made and why:
Choice #1: What type of bolt and hangers?
We've spent considerable time researching the bolts, hangers and top anchors we use on the routes at the North Rim. For hangers and top anchors, we generally use the highly respected Fixe brand. For bolts, we've standardized on Powers (formerly Rawl) Power-Bolt carbon steel "five-piece" expansion anchors. The typical bolt is 3/8" x 3" long. In softer rock, or if we feel the placement will be subjected to greater loads such as at an overhang or beneath a run-out crux, we use longer bolts or step up to 1/2" diameter.
The five-piece Powers bolts are used ubiquitously across North America in a vast variety of rock types and climates. Though they may look similar to bolts you find at Lowes or Ace, these are not the so-called "hardware store" bolts. Powers bolts are available only from specialty stores like Bolt and Anchor supply in Missoula, or online. The merits of this bolt are spelled out in Kinder's blog posts. They are also officially endorsed by the American Safe Climbing Association (ASCA),
"The generally accepted standards are the Rawl [Powers] five-piece bolt in both 3/8-inch and 1/2-inch widths, and in lengths appropriate for the type of rock - a minimum of three inches for hard rock (...) An advantage of the five-piece type is that they can be easily removed for replacement when they're old, 100 or so years from now." --ASCA Bomber Bolts
This is the bolt that we have used in all of our placements.
Powers 5-Piece bolts in Jon Siegrist's kit
"I bolted a number of routes while I was here"
www.jstarinorbit.com
Choice #2: What size of bolt?
The size of bolts we are using are 3/8" in either 3" or 3-1/2" lengths. But why not 1/2-inch bolts? Bigger is better, right? The answer to these questions can be found in the following excerpt from a Rock & Ice article,
"Forget about shear loading--a good, commonly used bolt such as the Powers PowerBolt and its ilk will not break. A 3/8-inch bolt of this type is rated to 7,000+ pounds in 6,000 psi concrete (basically granite) and 4,000 pounds in 2,000 psi concrete (hard sandstone). This is roughly the breaking strength range of carabineers and much higher than any rope’s maximum possible impact force. Scaling up your bolt to 1/2-inch using the premise that a 3/8-bolt could break is like carrying wood into a forest. (...) Tensile strength is another matter, since bolts can and do pull out, especially in softer rock, although in hard rock a 3/8-inch PowerBolt's tensile strength still exceeds that of the gear you'd clip to it. (...) Bolt length is the final consideration, and this is driven entirely by rock hardness or lack of it. In granite, a 2-inch-long bolt is, for practical purposes, as strong as a 3 1/2-inch-long bolt because both are overkill. Might as well go short there."
From Are 1/2-inch bolts really better than 3/8-inch?, Mark Biert via rockandice.com.
The bottom line is, if the bolt is well-placed (always keeping in mind the phrase "to err is human" and that humans place bolts) in the hard granite in Mill Creek, it is far stronger than anything in your safety system.
Choice #3: Stainless steel or carbon steel?
For most of us, stainless steel carries a connotation of superior quality, strength and durability. So what about stainless steel climbing bolts? Aren't they stronger than regular bolts? Longer lasting? If so, then why aren't we (and the majority of other first ascentionists) using them?
First, a surprising fact. Stainless bolts are not stronger than carbon steel. Their breaking strengths are actually identical as can be seen in the Powers data sheet here.
The main application of stainless steel is in moist, marine environments. As the ASCA states, "Use only stainless-steel bolts and hangers near saltwater." But stainless carries its own set of concerns and risks. Stainless is subject to galvanic corrosion caused by the mixing of metals, including the mixing of different grades of stainless itself, or even from contact with minerals in the rock. For starters, this means if you use stainless bolts, you must also use stainless hangers.
Here's what galvanic corrosion looks like up close. This is a picture of a carbon steel bolt combined with a stainless steel hanger at Mickey's Beach, California.
Stainless can also succumb to a unique type of failure called Stress Corrosion Cracking. This condition can leave a stainless bolt so degraded it breaks under body weight. In very bolt-hostile environments like Thailand, where "even the best stainless steel glue-in bolts simply snap off due to corrosion after a few years," (ASCA Thailand Rebolting) climbers have been forced to switch to custom-made titanium bolts. (Full details here.)
But in normal applications, such as the low rainfall, low humidity climate we have in western Montana, won't stainless steel bolts last longer than other materials? Certainly, they will. The 100 year estimate in the ASCA statement above may in fact refer to stainless, though the context isn't clear. To find out the expected lifespan of non-stainless, carbon steel bolts, we sent an email to the ASCA. From former president Chris McNamara (SuperTopo founder and publisher), we received this reply,
"My guess is that non stainless bolts should be replaced after 25-50 years."
From Greg Barnes, current ASCA president,
"The short answer is it's super hard to predict, but I wouldn't worry about it for at least 20 years (unless the bolts start obviously rusting before then)."
Barnes expands on this in greater detail, and if you're interested, we've posted his full response here. His closing statement serves as a good general guideline for our area,
"If I were you, I would keep an eye on the oldest bolts by looking for surface rust, then checking some after 15-20 years."
There are a couple of reasons not to use stainless steel bolts. One is that the bolts can be finicky to place. The metal is more brittle, making it easier to stress with misplaced hammer blows, or weaken or sheer off when tightening. This of course can be overcome with experience and practice.
The main reason for not using stainless is cost. For example, a box of 50 carbon steel 3/8 x 3 inch Power Bolts costs $69. A comparable box of 50 3/8 x 3-1/2 inch stainless Power Bolts costs $270, nearly 4 times as much. Let's assume a conservative estimate for the lifespan of carbon steel of 20 years. You could replace the bolts 3 times for a total of 80 years of use and still come out ahead on cost. And this does not take into account the higher cost of stainless hangers which must be paired with them. For stainless hangers you can add at least another $1 to every placement.
Put another way, for the same price it cost us to put up the current 25+ bolted pitches at Mill, we could all be climbing a grand total of 5 or 6 stainless equipped routes.
The bottom line is, in order to achieve the highest safety margin, all bolts, stainless or otherwise, require visual inspection over the years and decades after they are installed. This is another advantage of the sleeve-type bolts like the Powers (versus wedge-type bolts): they can actually be removed for inspection and then re-inserted back into the same hole. Granted, we are making a judgment call on whether or not the extra cost is worth the extra longevity. In not choosing stainless steel we are putting a burden on climbers 20 to 30 years from now to inspect and replace the bolts we are placing today. This means they should take the bolt out and look at it then replace if it looks suspect. Due to the solid and often overhanging nature of the rock at Mill, it is likely that most of the bolts we place today will be good at least until 2050. That said bolts that get wet more frequently should be checked more frequently.
"Climb at your own risk..." But we want to live!
If you're planning to put up a route we hope you can benefit from our research. If you're climbing at the North Rim, you now know what you're clipping. Be warned there are a lot of variables in climbing outside, and as everyone knows, climbing (even sport climbing) comes with at least some risk. There are no 100% guarantees any bolt will hold. However, we certainly want to keep climbing as long as possible, and we selected and installed these bolts in order to do just that. We’ve taken our share of falls on the routes we've put up; particularly Dane has whipped off the roof on QED-MF more than his share, thus the -MF suffix! Finally, things can be put in historical perspective. These modern era bolts are a helluva lot better than what climbers were using 30 years ago. We’ve clipped many a tiny, rusty button-head (as pictured below) in places like Tuolumne Meadows--running it out 20 ft blindly hoping these pitiful things might hold a 50-ft fall. And incredibly, they did. The modern 3/8-inch bolts seem huge by comparison. We can only wonder what climbers will clip in 2050.
Everyone who climbs long enough is guaranteed of coming face to face with the challenge of being runout on lead, sketched, arms failing with nothing to draw comfort from except that last bolt somewhere down beneath your feet. Piece of mind is why we've made careful decisions in selecting the hardware we install at the North Rim. This is why we've standardized on the Powers carbon steel bolt.
As Joe Kinder writes, the Powers bolt is "THE most solid bolt to use."
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For those seeking more information, a great starting point is the American Safe Climbing Association education page.
