Bolting Guidelines
1)How far should a new bolt be from another bolt or old bolt hole or a crack in the rock?
A)At least 10 diameters of the bolt, or at least 5 inches.
B)At least 6 inches from any other bolt, bolt hole or crack in the rock.
C)At least 12 inches from any other bolt, bolt hole, corner, pocket or crack in the rock.
D)At least 8 to 12 inches from any other bolt, bolt hole, corner, pocket or crack in the rock
2)What type of bolt should be replaced?
A)Pretty much any 1/4 inch bolt.
B)Any bolt that has a loose hanger that can not be tightened completely.
C)Bolts that are placed in poor rock or flakes.
D)Bolt or hanger that is damaged or distorted or very rusted.
E)Any home made looking hanger.
F)Any button head style bolt (usually have a center pin).
G)Any older hanger that is thinner than a quarter (ie: SMC with a pale yellow tinge).
H)Most bolts that have a hex head that requires an Allen wrench to tighten the bolt.
3)Should an old bolt hole be reused?
A)If the old bolt can be completely removed and the hole looks good with no excessive cratering, bolt hole is fairly perpendicular to rock face, andplacement is in good rock, it is better to reuse an old bolt hole.
B)It is much easier to enlarge an exiting bolt hole versus drilling a new hole and the enlarged hole often ends up with a much smoother hole shaft.
4)How should bolt placement areas be tested?
A)Tap on the surrounding rock and listen for hollow sounds or look for movement. If you have either of these, do not use that area.
B)Look at the rock for other bolts or bolt holes or cracks in the rock. that are within 5 inches.
C)Check if the rock is firmly attached and is not a loose or a small flake or the base of a horn that is cracked or similar weaknesses in the rock.
D)If placing new bolts for a rappel anchor, place the bolts at about head height.
5)What length of bolt should be used?
A)In soft rock, use bolts that are at least 6 inches long and in hard rock at least 3 inches long.
B)Use 3/8 inch by 2 1/2 inches in hard rock, 3/8 inch by 3 1/2 inches in medium rock and 1/2 inch by 4 1/2 inches glue-in bolt in soft rock..
6)What diameter of bolt should be used?
A)In all but the hardest rock, a 1/2 inch diameter bolt is preferred, but 3/8 inch diameter is acceptable.
B)Use the largest diameter bolt that is practical, but never less than 3/8 inch.
7)What type of bolt and hanger should be used?
A)Do not mix stainless steel and normal steel bolts and hangers. They can actually corrode each other. It is best to use stainless steel no matter where the bolt is placed.
B)Use a bolt that has a shear (straight down pull) rating of at least 5,000 pounds.
C)Larger diameter bolts will more likely resist bending which creates a leverage action that can increase tensile force (pulling straight out) and larger diameter bolts have more surface to rock area to increase friction for holding power.
D)The 3/8 and 1/2 inch Rawl five piece stainless steel bolt (also called a solid head sleeve bolt) for use in hard to medium-soft rock is the standard. It can work in sandstone, but the dust can jam the nut threads and keep it from tightening. This bolt requires animmaculately clean hole and a new bit. An old bit can create an undersized hole that makes it difficult to tighten the bolt. In hard rock, hangers will break before the bolt does. In medium rock, the 3/8 inch will pull out at 3,400 pounds and the 1/2 inch at 3,700 pounds.
E)The most consistently strong wedge style bolts, in descending order, are Petzl, Hilti, Ramset/Red Head (also known as Philips), Rawl and Wedge It. In hard rock, the Petzl was by far the strongest brand. Fixe bolts are also considered to be very strong wedge style bolts and the longer Fixe sizes have two expansion clips which work well in medium strength rock. The wedge style bolt requires very precise torque tightening to obtain full strength. The exterior threads for the wedge style bolt make them prone to work fatigue and are not as dependable as the sold head sleeve bolts. If used, consider using only 1/2 inch diameter wedge bolts. The wedge style bolt is a lot easier to place and tighten compared to the solid head sleeve bolt and the hole does not have to be as clean or precise.
F)Petzl Long Life stainless steel bolts are for hard rock only and can hold about 6,000 pounds in pull down and 4,000 pounds in pull out directions. They are very expensive and require a 12mm bit. The hole depth is only 2 inches, which, even in hard rock, is a short hole and will take less time to drill. This style of bolt does not work well in medium or soft rock, where it can fail at 2,000 pounds.
G)Glue in stainless steel bolts require precise hole diameter, amount of glue and almost require the use of a power drill. They can be the strongest and longest lasting type of bolt, but only if precisely installed. The glue actually bonds with the rock and can actually strengthen the surrounding rock and seals the hole from the elements. This is the only style of bolt recommended for soft rock. But, it takes 24 hours for the glue to fully cure.
H)Use only commercially made hangers that are rated for at least 5,000 pounds (22 kN).
I)The Petzl Coeur hanger is the only hanger that will accommodate a 1/2 inch bolt, unless a Rawl 1/2 inch five piece bolt is used, which will work with hangers made for 3/8 inch bolts.
8)Which bolts should you NOT use?
A)Externally threaded sleeve bolts are half as strong as solid head sleeve bolts, since the external treads reduce the effective diameter of the bolt by about half.
B)Any brand of torque bolt. Some claim the USE Diamond Taper Bolt works well, but the torque needed to get the most strength requires the use of a torque wrench. It is not possible to consistently hand tighten a torque bolt and get good results. The Wejit Anchor Bolt is another brand of torque bolt that should not be used.
C)Any sleeve and nail bolt (except the Petzl Long Life). The most common brand is the Star Dryvin which has a small star shape on the head of the nail. These are extremely weak bolts.
D)Any drop in bolt. These are anchors that have a soft lead sleeve that is driven in and then a machine bolt is screwed in to expand the sleeve.
E)Stud bolts with a bottom expansion pin. These require a precise hole depth so that the rear pin can be driven in the correct amount as the stud is driven into the hole. The external threads are weak and prone to work fatigue. No brand comes in stainless steel. Common brands are Rawl, Star, and Ramset/Red Head.
F)Self drill bolts can pull out at 700 pounds in medium rock. In hard rock, they can hold up to 3,000 pounds shear force, but it normally takes two of them since the drill portion of the bolt dulls easily.
9)How can you tell if the rock is soft, medium or hard?
A)Soft rock can be scratched with a finger nail and is in the 1,000 PSI range (limestone is an example)
B)Medium rock can not be scratched with a finger nail and is in the 2,000 PSI range. This is the range for a lot of the Smith Rock stuff (not counting the basalt areas). This hardness of rock can still be easily hand drilled.
C)Hard rock is in the 4,000 PSI range and includes marble and granite.
D)Most bolt tensile strengths (resists being pulled out) and shear strengths (resists pulling straight down) are based on testing in 2,000 and 4,000 PSI concrete which is a very uniform material. Rock is not nearly as uniform and each placement should be evaluated.
E)Rock can often have a hard crust that hides a much softer interior. This is especially seen in desert environments.
F)The best bolts for climbing have a highest strengths in the lowest PSI concrete.
10)Basic equipment needed to place and replace bolts
A)The basic piece of hardware is either a hand or power drill. A power tool is more efficient if replacing many bolts, but, because of the weight, a hand drill works well if only replacing a few bolts. A 1/4" to 3/8" enlargement by hand in Tuolumne granite with a sharp bit takes about 10 minutes by hand. If using a power drill, a handdrill backup is critical in case of battery failure.
B)A long very thin piton and a long medium thickness piton.
C)A good hammer.
D)A two foot long cat's claw, wrecking bar or crowbar with both achisel-type end and a hooked end with a slot for pulling nails.
E)A special tool that replaces the crowbar, called a “tuning fork,” can be ordered from the American Safe Climbing Association. It is much lighter and does not shear off bolts in the hole nearly as often as a crowbar.
F)A tool, such as 2 feet of 1/4 inch flexible tubing, puffer and test tube brush, for cleaning grit and dust out of the new hole.
G)Bolts, hangers, wrenches and whatever hardware the new bolts require for installation.
H)Vise grips for freeing stuck bits.
I)Long needle nose pliers.
J)Old biners and slings.
K)New 1/4 inch nuts and old 1/4 inch hanger.
L)Container for old bolts and hangers.
M)Safety glasses.
N)Funkness device which is a 2 foot long metal cable with a swaged eye on both ends.
O)New and sharp SDS bits in 1/4, 3/8 and 1/2 inch diameter and 6 inches long. Make sure the bits have the carbide “wings” on the tip that are a bit wider than the flute of the bit.
P)Make sure every piece of gear is secured, so you can hang each one from your rope or gear sling while working.
11)Bolt placement and replacement techniques
A)Clip an old biner and a sling to the old bolt and then loosen the bolt by tapping the hanger from side to side a few times with a hammer.
B)Pound a piton lengthwise between the hanger and the rock. Particularly tight bolts might require starting with a thin piton before using a thicker one. Do this repeatedly from many directions until the hanger is out about 1/2 inch.
C)Pull the old bolt out with a small crowbar or similar tool, such as a “tuning fork.”
D)Re-drill the existing hole to fit the new bolt.
E)If drilling a new hole, take special care that the first inch of the hole is perpendicular and a uniform diameter. Don’t let the bit wobble or change angles. As the hole gets deeper, do not let the bit rest on the sides of the hole.
F)The hammer strikes should be firm, not a tap and not a slam like driving a framing nail.
G)Between each blow of the hammer, turn the hand drill only 1/8 of a revolution. Once the hole gets started, hold the hand drill loosely so that the bit rebounds a bit after the blow. This will help clean out the rock dust in the end of the hole and keep the bit from binding.
H)If the bit does bind, gently wiggle the bit back and forth to free it. If the bit is binding a lot, try more frequent but lighter taps of the hammer.
I)Stop every 50 blows and clean out the hole using a brush and tubing or puffer.
J)The hole should be at least 1/4inch deeper than the bolt. Once the hole is finished, clean the hole using a brush and plastic tubing or puffer. You should see no rock dust coming out of the hole when blowing hard with plastic tubing.
K)Install the new bolt by inserting it into the hole and tightening the head with a wrench to the recommended torque. Practice tightening bolts using a torque wrench to get a feel for how tight a bolt should be. A bolt can be sheared off from over tightening, or almost sheered off, but still look solid.
L)If the bolt is tightening, but then starts to spin, try clipping a sling to the hanger and pulling out at the same time. If it still spins and will not tighten all the way, remove the bolt and start over. Do not leave a partially installed bolt!
M)It should take firm tapping to drive in the bolt. If it does not or you can pull the bolt back out with your fingers, the hole is too big. You can drill to a larger diameter if you have larger bolts, or drill a new hole.
N)Empirical evidence suggests that it's not necessary to seal the hole with glue.
O)If the old bolt, or part of the old bolt, just will not come out, fill the hole with an epoxy and work in some rock dust to hide the hole. One brand of epoxy is “Repair It Quick” which can be found at Home Depot.
P)Sometimes an old bolt that just will not come out may require bending the bolt back and forth until it breaks off. Drive the bolt back in if possible and fill with epoxy and rock dust.
Q)A new hole in hard rock that is 2 1/2 inches deep may take up to half an hour and the same in soft rock for a 4 1/2 deep hole.
R)In most cases you will want to be either on rappel and hanging from prusiks or ascenders or on a tight belay from above.
Sources
Todd Vogel. 1994. Rock and Ice. Bolts: bomber or time bombs? How to tell the difference - and do something about it.
Chris McNamara. 2003. American Safe Climbing Association. How to Rebolt.
Duane Raleigh. 2003. Climbing Magazine. Mechanical Bolts. The Nuts and Bolts.
Duane Raleigh. 2003. Climbing Magazine. Adhesive Bolts. Sticky Business.
Duane Raleigh. 2003. Climbing Magazine. Dangerous Bolts - Bolts to Avoid.
Neil Monteith & Lee Cujes. Safer Cliffs Australia. How to Bolt.
Jeff Achey. Climbing. Escape Systems. Hand-Drilling an Emergency Anchor.
John Long and Bob Gaines. 2006. Climbing Anchors. 2nd Edition. Fixed Gear - Bolts.