Project Caving and Permanent Rigging
by
Benjamin Schwartz, NSS #32206, benandcori@excite.com
Long-term
cave exploration projects demand long-term rigging. For safety and low
maintenance, rigging must resist water, mud, corrosive minerals, time, and
caver traffic. This article looks at the requirements for permanent rigging,
the limitations of widely available technologies, and some alternative hardware
that I have identified and used extensively.
A
TYPICAL SCENARIO
The
cave has gone deep, but trips are infrequent due to flood hazards and caving
schedules. The breakout occurred four years ago: a dig in a narrow canyon led
to a second drop. Four more drops have been found, with long, wet, difficult
crawls in-between. Each drop has been rigged at great expense in time and
effort. On the last trip, a breathtaking lead climb resulted in a static rope
hanging ready for further exploration. It's time for another trip. The cavers
are ready. Is the rigging ready?
|
|
Anchors as an investment The
anchors at this drop in a West Virginia cave are under heavy spray for most
of the year. The lower
anchor is a steel hanger made from angle-iron and a high-grade steel
bolt. It is 20 years old and has been unsafe for probably 15 of those years. The upper
anchor is a stainless steel hanger on a 3/8-inch stainless steel
stud. It was installed using a hammer drill that was in the cave for an aid
climb. It is 10 years old, and will last for hundreds of years. (J.
Ganter photo) |
PROBLEMS
OF PERMANENT RIGGING IN MULTI-YEAR CAVING PROJECTS
Project
caving often pushes the limits of both caves and cavers. Explorers must strike
a balance between carrying too much or too little equipment. Not knowing what
lies ahead forces us to carry rigging equipment, which we may or may not need,
or risk having to turn around at a climb or drop. Weight and bulk are always
concerns, and this affects what types of artificial anchors (bolts) can be set
when natural anchors are not available.
Ideally,
we would set long, single-piece anchors made of stainless steel. However, these
types of anchors (studs) require a separate drill to create a deep hole.
Self-drilling anchors have a built-in drill, but because of the required
hardness they cannot be made of stainless steel. (For details see Artificial
caving anchors for the present and future," May 1990 NSS News or http://nervenet.zocalo.net/jg/c/pubs/)
Few are
willing to carry a gas or battery-powered hammer drill on push trips. Although
it would be nice to have long, 10mm stainless steel studs and hangers quickly
placed at every drop, this is often impractical in deep, wet, body-contact
caves.
Instead,
our equipment usually consists of a fairly lightweight and compact self-drive
kit, with enough anchors, hangers, and aid gear to rig several drops or do a short
climb. In the past, most of us have used Petzl’s 8mm self-drive anchors and
hangers, combined with carabiners or steel quick-links. Petzl gear is easy to
purchase, easy to use, lightweight, and relatively inexpensive. Carabiners and
steel quick-links are also easy to acquire.
|
However,
there are corrosion problems associated with leaving aluminum hangers,
aluminum carabiners, steel cap screws, and steel quick-links hanging in wet
and muddy caves for a multi-year project. If the project is seasonal, rigging
can be removed, ropes can be removed or stashed in the cave, and everything
can easily be inspected or replaced before the next season. This still takes
quite a bit of time though. |
|
Note: Some cavers debate the safety
of using 8mm self-drive anchors as primary rig points. I am not debating this
point here; I use them. However, the reliability of any type of anchor
depends upon its proper placement and continuous inspection. Only you are
responsible for checking the rigging you clip into! |
In
long-term projects, the rigging on frequently traveled "trade routes"
can quickly become three, five, or even 10 years old. Removing and replacing
badly corroded rigging may be postponed "until the next trip" and is sometimes
delayed for far longer than it should be. Almost nobody wants to take the time
to maintain rigging on the way out after a long, hard trip.
Even if
the cave is visited frequently, inspection is uncertain. Who can be sure that
an aluminum hanger is truly in good shape? Aluminum can be very deceiving and
difficult to check for weaknesses. After only one year in some very corrosive
caves environments, hangers can exhibit deep surface pitting, gel deposits,
invisible corrosion, and even calcite coatings. With all the things that can go
wrong in vertical caving, the last thing anyone wants to be worrying about is
whether the carabiner and hanger at the top of a 2-year-old aid climb is going
to fail before someone gets to the top and checks it.
With
these problems in mind, I began searching for something to replace aluminum
both in comparable price and weight, with more durability. An excellent choice
would be to use stainless steel. Starting at the rope and working towards the
anchor, I looked for opportunities to replace aluminum or steel rigging
components with stainless steel.
A
SOLUTION: STAINLESS STEEL COMPONENTS
Here is
a cost-effective way of reducing the amount of speculation and anxiety
concerning aging rigging, while at the same time reducing some of the hazards
of vertical caving.
I
priced box quantities (20) of Long Oval Stainless Maillon Rapide 7mm
quick-links from several speleo-vendors. These have a gate width of 9/16-inch
which easily accommodates ropes commonly used in caving. The cost of these is
less than all but the cheapest of locking ‘biners and they will last almost
indefinitely with some basic care. In addition, they weigh less than the
average ‘biner (42 grams compared to about 65 grams) and are much more
space-efficient as far as both size and packability are concerned. As for
strength, they are more than strong enough, with a stated working load limit of
580kg (safety factor of 5).
The
next thing was to find a stainless steel hanger. With all the climbing
companies that make hangers, it seemed many of them must make an 8mm hanger
just for this purpose. I soon found the opposite to be true after calling
several companies and gear manufacturers. None of them made any 8mm equipment
and they either referred me to Petzl aluminum gear, or suggested using an 8mm
washer over a 10mm hanger. This was an unacceptable solution for me. I even
looked into having someone custom stamp and bend a large quantity of 8mm
hangers.
The
only thing that comes close to matching my requirements is an SMC 5/16-inch
hanger. (5/16 and 8mm are almost identical in size.) The problem is that they
are fairly expensive ($3.50 ea.) and have a very small attachment hole. I
needed something comparable in price that could easily accommodate two
carabiners during use on aid climbs.
|
More
searching on the Internet turned up a company in Spain called Fixe. They sell
8mm stainless hangers with a large attachment hole. I called the only U.S.
distributor of Fixe products (Kevin Daniels & Associates) and got pricing
for 150 hangers. In addition to the cost of the hangers, there were still
costs for shipping, stainless cap screws, and the small capture/seal O-rings
similar to the Petzl design that keeps the cap screw attached to the hanger
until installation. With all this added to the cost, the price is only
slightly higher than a Petzl hanger. ($2.32 compared to $2.25±) This price
includes the cost of having to buy 200 each of both the cap screws and
O-rings. (Package quantities on these were 100 each.) |
|
The
total weight is more than the Petzl aluminum hanger, (72 grams compared to 30
grams) but I feel the increased life span and peace of mind more than offset
the few ounces added to an already heavy pack.
CONCLUSION
For a
slightly higher cost, I now have a permanent hardware option that will last me
a lifetime. Each part of the rigging hardware (except the anchor) can easily be
re-used an almost unlimited number of times. Two weak links in a permanent or
long-term rig point have essentially been eliminated.
The
self-drive anchor is now the only non-stainless component. Fortunately, it is
somewhat protected by being surrounded by rock and covered by the O-ring and
hanger.
Some
cavers fill the inside of the anchor with petroleum jelly from a small squeeze
tube to help exclude water and reduce rusting.
The
pricing of all these items was done for large quantities. At quantities of 10
or 20 each, the price would be somewhat higher (Note: see new information below
for smaller quantities). As it currently stands, I can set an anchor and
permanently rig it for around $9.00. (Whatever happened to caving as a cheap
hobby?!) This is the same as, or less than, the cost of using a Petzl anchor,
Petzl hanger, and a carabiner.
Thank
you to John Ganter and Phil Lucas for making suggestions and providing
constructive criticism
Which anchor? by John Ganter
All
anchors have advantages and disadvantages. The 8mm anchors that Ben discusses
are small -- not much bigger than a 1/4-inch anchor. By using them you are accepting
risk of lowered strength and reliability. And since anchors usually become
permanent cave " infrastructure," some future users may not be aware
of this risk. But on the other hand they are easier than 10mm to drill, and the
drivers are available.
Here is
a comparison of anchor systems to help you decide on options:
|
|
Advantages |
Disadvantages |
|
Natural
anchor(s) |
- Less damage to cave |
- May take extra skill to rig |
|
Stainless
studs |
- Single body thus very strong |
- Requires hand drill (1) or hammer drill to install |
|
10mm
self-drive |
- Much better safety margin than 8mm |
- Harder to drill than 8mm |
|
8mm
self-drive |
- Easier to drill than 10mm |
- Low safety margin |
If you
decide to go with the 8mm anchor, try to compensate for the disadvantages with
the following practices. (See "Artificial Rigging Anchors for the Present
and Future" http://nerve-net.zocalo.com/jg/c/pubs/anchors/default.htm
for analysis.)
Installation
and maintenance
Plan your anchors carefully. Visualize what it
will be like to get on and off rope. Have your companions critique the possible
locations. Think about different conditions, like water levels. If you can get
it right the first time, others will be less likely to come along and set more
anchors!
Use two anchors for a rig point
Set the anchor to the right depth; any
protrusion weakens the anchor greatly!
Make sure the cap screw is tight and stays
tight; most strength comes from the hanger-to-rock friction, not the anchor
itself!
Use stainless steel cap screw and hanger; you
have no safety margin for rusting!
If you have to use aluminum or plain steel
components, return and replace them with stainless as soon as possible!
Consider coating the outside of the anchor with
silicone sealant just before installing it. This will reduce rusting.
Fill the inside of the anchor with grease or
Vaseline
Consider placing a plastic or aluminum tag on
or near the anchor with information on date and type. (May not be practical in
heavy mud, flood-prone areas, etc.)
Remove cap screw and inspect anchor and
anchor/rock (as much as can be seen) every three to five years
Use
Rig rope to equalize the load between the two
anchors
Avoid falls and pendulums
Do not tandem ascend (two people climbing on
the rope at the same time)
Inform and remind project members and other
users about the anchor types and limitations (if possible)
Permanent rigging components illustrated by John Ganter,
with Ben Schwartz
This
section provides more details on the components discussed above.
The US
sizes can be considered a "legacy" system. For example, in the 1980s
I bought a large number of 3/8-inch self-drives that were being closed out by a
hardware store. Art Petit made me a high-quality aluminum and stainless steel
driver. So I plan to use these supplies until they are gone, and other cavers
will do the same.
But we
should use the best possible materials for the remainder of the anchor system:
the cap screws and hangers. Sources of these items are listed in the 3/8-inch
column.
|
|
Petzl-based
8mm |
Petzl-based
10mm |
3/8-inch |
Illustration |
|
Driver |
Petzl PERFO PRO P09 or PERFO SPE P08 |
- Raumer Stroker universal driver with 10mm insert. Available through
Expé and Inner Mountain Outfitters,
about $35? -
Adapter for Petzl 8mm driver has been discontinued (2).
We are looking for a source. |
Current US manufacturer unknown (3) |
|
|
Bolt
(technically a "cap screw") |
Metric SS Hex Head Cap Screw, M8 X 16 mm long, 1.25 mm Pitch, Fully
Threaded |
3/8 x 16, 3/4-inch SS Hex Head Cap Screw, NC thread, Fully Threaded |
|
|
|
Rapid
link |
7mm Long Oval SS Quick-Links |
same as Petzl 8mm |
same as Petzl 8mm |
|
|
Hanger |
Fixe 8mm SS Hanger |
Petzl COEUR P34050 10mm hole |
Petzl COEUR P34050 10mm hole |
|
|
O-ring |
Silicone O-ring, 1/4" ID, 3/8" OD |
same as Petzl 8mm |
same as Petzl 8mm |
|
|
Anchor |
Petzl CHEVILLE AUTOFOREUSE P12 |
Inner Mountain Outfitters has
some Petzls |
Rawl seems to have discontinued these anchors, others? (3) |
|
|
Dimensions |
- Hole in rock is 12mm |
TBD |
- Hole in rock is 1/2-inch |
Images courtesy of Petzl and McMaster-Carr |
Notes
SS = stainless steel.
Not all stainless steels are rust resistant. You want 200/300 Series austenitic
alloys. Most "18-8" (18% chromium and 8% nickel) steel is austenitic.
This includes types 302, 303, 304, and 316. 316 is for marine uses and is
probably not worth the extra cost for cave environments if other options are
available. Avoid 4XX (400 series): these are ferritic or martensitic steels and
they may rust. For an overview of series, see http://www.ssina.com/ssprod.html.
For compositions, see http://www.gibsontube.com/table6.htm.
(Thanks to Bill Storage for SS information.)
|
(1) Hand drills are available for placing studs. These
typically consist of a holder that accepts bits like those used in hammer
drills (SDS shank). One model is the Pika Rock Drill, available from
Adventure Gear. |
|
(2) Why has Petzl discontinued 10mm self-drive
anchors? No one seems to know, but the theory is that Petzl believes that
caving anchors should be either 8mm with aluminum hangers for short-term use or
stainless studs set with a hammer drill for long-term use. The problem is that
neither approach works for some deep, tight, wet cave projects.
(3) Self-drive anchors and hand drivers are mostly
obsolete for construction because of hammer drills. From an engineering
standpoint, it is much better to have drill and anchor separate. Stainless
studs are far superior to self-drives in almost every way. So self-drives are
relegated to rock climbing and caving, where Petzl is the international
standard.
(4) Fixe hangars are available in quantity 150 for $1.75
each, plus shipping, directly from the importer: K. Daniels and Associates (see
Sources).
Sources
Adventure
Gear, http://www.ewalker.com/adgear,
anchors at http://www.ewalker.com/adgear/nutbolt.htm
Expé, http://www.expe.net/, available through Inner Mountain
Outfitters
Fixe, http://www.fixeclimbing.com/, anchors
at http://www.fixeclimbing.com/fixeclimbing/ang/productos/anclajes/anclajdr.htm
Inner
Mountain Outfitters, http://www.caves.org/imo
K.
Daniels and Associates, 14891 Sabre Lane, Huntington Beach, CA 92647 Phone:
(714) 751-5038 Fax: (714) 540-3845
Kong-Bonaiti,
http://www.kong.it/, anchors at http://www.kong.it/climbin2.htm
Metolius, http://www.metoliusclimbing.com/,
hangers at http://www.metoliusclimbing.com/stainlesshanger.htm
McMaster-Carr
Supply Co., nationwide offices, Chicago is (630) 833-0300, http://www.mcmaster.com/
Petzl, http://www.petzl.com/, anchors at http://www.petzl.com/FRENG/franchors/anchorframe.html
Pika
Mountaineering, http://www.pikamtn.com/
Raumer,
available through Expé
Acknowledgements
Thanks
to Tommy Shifflett and Alex Sproul for suggestions and information.
Version 1.95, 12 November 1999. Version 1 was published in the NSS
News, October 1999.
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