• Marking the Middle of a Rope
  • Fitting Rock Shoes to Problematic Feet
  • Defining the Cheater Stick and Stick Clip
  • When Your Partner Steals Your Gear...
  • Can You Climb on a Wet Rope?
  • Can You Decrease Fall Factor?
  • Should You Be Allowed to Practice Lead Falls in the Gym?
  • Rope Certifications: Twins, Doubles, or Both?
  • Are Cam Placements Compromised in Wet Rock?
  • What's the Correct Way to Girth Hitch to Your Harness?
  • Choosing Ice Screw Length
  • The Holding Power of Nuts
  • Should You Clip the Belay As Your First Lead Pro?
  • Should I Worry About Spinning Bolt Hangers?
  • Belay-Loop Myth
  • Rock Cleaning Made Easy
  • Why Not Clip Directly to Cam-Stem Loops?
  • What's The Protocol For Naming a Route After Yourself?
  • Is Dropped Gear Still Safe?
  • Can Ropes and Slings Be Contaminated By Essential Oils?
  • Is It Okay to Wear Socks with Rock Climbing Shoes?
  • How Should You Test Gear Placements?
  • Can You Use Adhesive Tape on Ropes, Cords, Webbing?
  • A Better EDK?
  • What's the Difference Between a Double and a Single Rope?
  • Does It Count As a Free Ascent If You Grab the Anchor?
  • I Found a Rope - Is it Safe to Use?
  • Am I Using a Daisy Chain Wrong?
  • Should I Buy a Plastic or Foam Helmet?
  • Why Doesn't Anyone Climb in Knickers Anymore?
  • Is Weight or Range More Important in Cams?
  • The Mysterious Phenomenon of Rope Shrinkage
  • Worst-Case Scenario - A Factor 2 Fall
  • The Nuts and Bolts of Nuts and Bolts
  • Why Are Climbing Shoes So Expensive?
  • Flaws in the Yosemite Decimal System
  • How Durable is Trad Gear?
  • Using Super Glue on Your Fingers
  • The Worst Gear Ever Invented
  • Why Do People Use Oval Biners?
  • Is it Ethical to Clean a New Route?
  • Aid Climbing = Moped Riding
  • Will Sweat Harm My Harness?
  • Should You Use Rope or Webbing to Connect to an Anchor?
  • Choosing Between C4s and Friends
  • Can You Lead On a Static Rope?
  • Can I Use Climbing Bolts For Anchors in a Gym?
  • Are Falls Held or Breaking Strength More Important In a Rope?
  • Does Poop Harm a Climbing Rope?
  • Are Homemade Draws Reliable?
  • Shopping for Economy Carabiners
  • When You Fly, Can You Carry On Climbing Gear?
  • Can I Trust Fixed Draws?
  • Which Helmet WIll Fit My Big Head?
  • Are Adjustable Leg Loops Useful?
  • Should I clip Ice Screws with Screamers?
  • How do I Make a Bomber Anchor?
  • Can I Modify my Crampon Without Compromising the Integrity?
  • Hot Versus Cold Forging
  • Caring For Your Fingertips
  • Are Sewn Slings Stronger Than Knotted Ones?
  • When to Replace Climbing Webbing
  • Using Grip Dip To Color Code Gear
  • The Benefits of Cotton
  • How to Pull a Rappel Rope
  • How to Properly Orient a Carabiner Gate
  • Are My Fuzzy Quickdraws Safe?
  • How to Stretch Climbing Shoes
  • Are 1/2-inch bolts really better than 3/8-inch?
  • Should I Resole My Rock Shoes?
  • How to Hand Drill
  • Lonely Climber Looking for Woman
  • Is My Invented Knot Safe?
  • Difference Between Double and Twin Ropes
  • Dealing With an Argumentative Partner
  • Will Antifreeze Ruin Rope?
  • Why Is a Rack Called a Rack?
  • Rock Shoes For a Big Guy
  • Do They Kill Geese To Get Down?
  • How to Wash a Rope
  • Do Cam Teeth Do Anything?
  • Can I Fix Delaminated Rock Shoes?
  • Can I Mix a Static With a Dynamic Rope for Rappelling?
  • Should You Lower Or Rap Through Anchors?
  • How Should The Middle Man Tie In?
  • How Do I Get a Good Climbing Man?
  • Do Falls Weaken Bolts?
  • Should I Rope Solo?
  • Should I Angle Ice Screws Down?
  • How Should Old Climbers Train?
  • Can I Make a Belay Loop?
  • Reusing Ice Screw Holes
  • Overcoming the Fear of Falling
  • Choosing a Stove Fuel
  • Will My Hiking Boots Work With Crampons?
  • Do Heavy People Shock Load the Rope?
  • Can Offset Cams Subsitute for Regular Cams?
  • Can I Resling My Cams Myself?
  • Are Older Alien Cams Safe?
  • Will sports drinks freeze more slowly than water?
  • The Truth About Climbing Supplements
  • Can I Make My Leashed Tools, Leashless?
  • Rope Stretch Facts
  • How To Cut a Rope Without a Knife
  • Secrets of the Toprope
  • How to Sharpen Crampons
  • Should I Become a Climbing Guide?
  • Preventing Climbing Rope Wear
  • How to Remove an Old Bolt
  • How to Customize Ice Tool Picks
  • Double Rope Facts
  • Do It Yourself Fruit Boots
  • Climbing Rope Sheath Slippage
  • Rockfall Safety
  • Do Screamers Work?
  • Climbing Skin Care
  • Selecting a Gym Rope
  • Quick Links for Climbing
  • Are Russian Cams Good?
  • When To Retire Climbing Gear and Ropes
  • Should I Get a Link Cam?
  • How to Get a Climbing Mate
  • Will Dog Urine Harm My Rope?
  • Using Steel Carabiners for Fixed Quickdraws
  • Petzl Tibloc and Climbing Rope Sheath Damage
  • Overcoming Anger
  • Fixing a Spinning Bolt
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    Do Falls Weaken Bolts?

    25-Jun-2010
    By

    Will falling on a bolt weaken it?

    If dripping water can over time reduce granite to sand, you can imagine that falling on a bolt weakens it. But, realistically, you cannot weaken a 3/8- or 1/2-inch bolt that was properly placed in solid rock merely by falling on it, any more than you can bend a spoon just by thinking about it.

    For a bolt to weaken materially from a fall you would have to exceed its fatigue strength and you would have to do so thousands if not tens of thousands of times. Fatigue failure is caused by repeated changes in tension in the bolt, such as you would have with frequent weighting and unweighting. You prevent fatigue failure simply by tightening down the bolt. Torquing down a bolt stretches it slightly, creating tension. A properly tightened bolt acts as a rigid spring pulling the hanger and the rock together. As long as this tension is greater than the load caused by a fall, the bolt won’t feel any tension change and won’t fail in fatigue. 

    The trick is to torque down the bolt properly—a loose bolt could fail! Proper torque depends on the bolt diameter, grade, the co-efficient of friction between the bolt and rock and bolt material (zinc-plated or stainless). Most manufacturers provide recommended torques, but these are impractical because we don’t use torque wrenches, and even if we did, rock variables would make the specifications little better than guesses. 

    Not to worry, because as long as you wrench a bolt down tight, you are in the ball game. Power Fasteners, for example, recommends torquing its Power/Rawl 5-piece ½-inch bolt to 35 to 45 foot-pounds. But they also say you can tighten it “three to five turns past finger tight.” To me, their recommendation is the maximum I can exert on a bolt before the wrench or socket skips off and I bark my knuckles. In short, this is a very tight bolt. 

    You didn’t ask about other bolt-failure modes, but while we’re at it I have had two bolts break and heard of others. The first, in 1982, was a ¼-inch by 1¼-inch split-shank, threaded Rawl Drive at a two-bolt hanging belay on El Cap’s Iron Hawk. This bolt, probably set in 1977 during the first ascent, sheared under body weight. It broke despite being less than five years old and likely never having held a fall. The culprit? Corrosion. The bolt, placed in what I would consider an arid environment, was rusted nearly all the way through. Sure, we don’t use 1/4-inch bolts anymore, but corrosion can cause any diameter bolt to fail. You can’t completely prevent corrosion, but you can slow it to a point where it becomes negligible by using corrosion-resistant stainless steel. For more on corrosion and anchors to combat it, see Field Tested on page 72. 

    The second failure was in a 3/8-inch by 3-inch zinc-plated Rawl 5-piece that broke in the early 1990s while I was tightening it down with a short crescent wrench. The hex head on this bolt twisted off under light pressure, so overtorquing wasn’t the problem. I called Rawl and spoke with their engineers, who said that the likely culprit was an air bubble that developed in the metal during the manufacturing process. The bolt was probably defective. 

    Because bolts can and do fail, and for a variety of reasons, never trust a lone bolt at a rappel, belay or lowering station—that seemingly defective bolt I was placing was going to be a one-bolt rap anchor 200 feet off the deck. If I had tightened it just a little bit less, it wouldn’t have broken in my hands, but while I was on rappel. OMG!

     

    Find More Climbing Gear Advice Here

     

    GOT A QUESTION? E-mail Gear Guy! rockandicegearguy@gmail.com

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