Equipment Testing
EQUIPMENT TESTING
Due to poor conditions of weather the Oregon chapter was not able to complete its series of tests last year. It is anticipated that there will be a report in next year’s report.
Mr. John Armitage, an AAC member presently studying in England, has passed on some worthwhile comments concerning ropes. He quotes the results of abrasion tests on manilla and nylon rope —presumably of the same size; the manilla rope retained 84% strength and nylon only 24%, under dry conditions, under wet conditions figures were, respectively, 64% and 53% (Ropes from man-made fibres No. 555 89 pages; $3.00 from British Ropes Ltd., Austin & Hope Lane, Charlton, London S.E. 7, England).
Armitage also points out that some of the European Kernmantle ropes (11mm) will pass 2 U.I.A.A. falls but never 3 falls, and after the 2 severe falls it will not appear to be damaged by ordinary inspection. So we repeat again that a rope that has caught a severe fall should be retired. It has done its duty.
A further point was made by Armitage that 7/16 inch ropes should be the minimum diameter. He points out that a worn 7/16 inch rope is still as strong as a new 3/8 inch rope. He further states that it is becoming a universal practice in Britain and on the Continent to discourage the use of the single 3/8 inch rope for climbing. In fact such ropes (3/8 inch) are being referred to as half-ropes to discourage their use.
The following are reports of rope and carabiner tests done by Serena Bousman.* The rope tests were performed at the Plymouth Cordage Company under the supervision of Mr. A. Wirtzburger. A standard rope testing machine was used and the tests were conducted according to the methods outlined in the Cordage Institute Standard Test Methods for Synthetic Fiber Ropes (Nov. 10, 1960).
(“Tensile strength shall be determined by using eye spliced specimens 3-5 feet in the clear between the last tucks of the splices. In all cases a tapered splice shall be used. Experience has shown that for nylon and poly-
ethylene ropes a minimum of 4 full and 2 split tucks should be used. The inside diameter of each eye shall not be less than 7 inches and not more than 15 inches.
“The spliced specimens shall be broken on any suitable testing machine with the speed of the moving head controlled to 3" ± 1" per minute, under no load.
“Conditioning of test specimens: For ropes made from nylon test specimens shall be thoroughly conditioned prior to tensile testing in an atmosphere of 65% RH and 70°F.”)
New 7/16 inch diameter diameter Mountain Goldline was used for all tests unless otherwise stated.
*(Sponsored by Boston University College of Engineering.)
TABLE 1 Tensile Strength —dry
Failure
lbs.
elongation
%
Comments
6050
49.2
Broke at splice
5420
42.0
Broke at splice
5660
45.6
Broke at splice; this specimen had previously been used in an attempt to break rope over a carabiner which broke at 5375 lbs. The elongation readings taken did not differ significantly from those of unstretched rope.
6200
47.0
Broke at splice; this sample was loaded to 1000 lbs. and released 10 consecutive times. The elongation at 1000 lbs. was the same each time.
Tensile Strength —wet
5830
50.0
Broke at splice; soaked in fresh water 24 hours.
5420
48.0
Broke at splice; soaked in fresh water 24 hours.
Knot
Test # 1
Value # 2
(lbs.) # 3
Ave.
(lbs.)
% unknotted dry strength
Butterfly
4040
3700
4150
3963
69.5
Bowline on a Coil
3907
3220
3580
3569
63.0
Bowline
3795
3620
3705
3707
65.0
Fisherman’s
3250
2900
3260
3136
55.0
Sheet bend
2690
2860
2860
2803
49.0
Prussik
2100
2200
(comments)
1/4" on 7/16" new mountain lay Goldline some slipping approximately at 1500 as knot tightened; 1/4" broke at knot in both cases.
Prussik
2775
2400*
* 2100
5/16" on 7/16" new mountain lay Goldline some slipping between 1000 and 2000.
**One strand ol 7/16" and one strand of 5/16" broke at 2400 at the knot.
The 5/16" broke at the knot in the other two tests.
The percentage reductions caused by the knot in the 7/16 inch Goldline are similar to those reported by Leonard and Wexler for 5/16 inch manila and 1/4 inch nylon (Sierra Club Bulletin 31, 68-100, 1946). Knots do reduce the tensile strength of the rope probably as a result of the angulation of the rope.
A number of carabiners of different types were obtained in the open market from suppliers. The carabiners were tested on a Tinius Olsen Tensile Tester. The range selected for the test was 1-30,000 lbs. Breaking time varied between 10 and 90 seconds. No correlation was noted between time and strength.
Stubai steel
2700
hinge pin sheared, stretched at approximately 1300
3000
— do —
3150
— do —
3200
— do —
3250
— do-
Cassin aluminum
4450
Tongue broke, hinge deformed, stretched at approximately 1500, broke top rear
5100
Closing pin pulled out of lip, hinge deformed, stretched approximately at 1500
5100
Tongue broke, hinge deformed, stretched approximately 1500, broke top rear
5450
Tongue broke, hinge deformed, stretched approximately 1500
Note: Those which did not fail due to fracture were not tested to their upper limit due to danger from flying pieces. It is assumed that they would have fractured if stretched further.
Bedayan aluminum
2250
Tongue broke, stretched at approximately 1500, no break.
2500
— do —
2500
— do —
2750
— do —
2800
Tongue broke, broke top rear when stretched less than above.
Kamet aluminum locking —Tested in locked position.
3300
Began stretching, broke top rear
3450
— do —
3600
— do —
3700
— do —
3750
— do —
Chouinard aluminum
3450
Tongue broke, stretched at approximately 2500, broke top rear
4250
— do —
4400
— do —
4400
— do —
4500
— do —
Army aluminum —No identifying marks.
1850
2000
Tongue broke, stretched at approximately 1100, broke bottom rear
— do— (see note for Cassin Al.)
2250
-do- ( ” )
Cassin steel locking —Tested in locked position.
6300
Tongue and lip deformed, bearing failure one side of tongue fractured, stretched at approximately 2500
6450
— do —
6700
— do —
6750
Hinge pin pulled through bottom front, stretched at approximately 2500
7350
Tongue and lip deformed, bearing failure one side of tongue fractured, stretched at approximately 2500
Cassin steel
3550
Tongue and lips deformed, bearing failure, stretched at approximately 2200
3600
— do —
Marwa steel
6450
Tongue and lip bearing failure, stretched at approximately 3000
6450
— do —
6550
— do —
7050
— do —
7350
— do —
The results of the carabiner tests are similar to those reports (in last year’s report) from Everett Lasher. Lasher reported that the Army aluminum carabiner failed at about 2000 lbs. There was one instance in this series above in which an Army aluminum carabiner failed at less than 2000 lbs. This study also points out that a number of these carabiners will show signs of deformation before failure. If such deformities are noted in carabiners in use they should be discarded. It is usually the aluminum (Army and Cassin, and Bedayan) types that tend to be deformed below 2000 lbs. although the Stubai (steel) also showed deformity at 1300 lbs.
SAFETY COMMITTEE, AMERICAN ALPINE CLUB, 1966
Benjamin G. Ferris, Jr., Chairman
Weston, Massachusetts
William L. Putnam
Springfield, Massachusetts
Arnold Wexler
Washington, D. C.
Harold Walton
Boulder, Colorado
Thomas O. Nevison
Albuquerque, New Mexico
Ross Petrie
Portland, Oregon
J. Alex Maxwell
Yakima, Washington
David Harrah
Riverside, California
A1 Steck
Berkeley, California
William Davis
Anchorage, Alaska
ALPINE CLUB OF CANADA
Paddy Sherman
Vancouver, British Columbia
EQUIPMENT TESTING
Jack Baldwin
Portland, Oregon
RESCUE OPERATIONS COMMITTEE
Paul M. Williams, Chairman
Seattle, Washington