Week 2 (Ropes/Knots/Splices) Flashcards
what are three common types of rope used?
Natural
Synthetic
Wire rope
what is generally the only natural fiber rope used for rigging purposes?
1 grade manila
manila rope is subject to _____ and many companies __________the use of it?
rot/prohibit
natural fiber ropes must be removed from service when what conditions are found?
-abnormal wear
-powdered fiber in strands
-broken/cut fibers
-variations in size or roundness of strands
what kind of rope do these characteristics describe?
-high weight and strength ratio/ absorbs little moisture/doesn’t stiffen when wet/good dielectric properties/resistant to damage caused by water, mildew?
Synthetic
_______ rope can be 2 1/2 times stringer than _______ of the same diameter?
synthetic/manila
synthetic ropes are made out of what materials?
nylon, polyester, polypropylene, polyethylene
what are the characteristics of 1/2 inch, three strand synthetic rope?
-6.7 lbs per 100 foot
-catalog breaking strength of 5,800 lbs
what is duraplex rope commonly used for?
hand lines
what is the catalog breaking strength of 1/2 inch duraplex rope?
6,700 lbs
what common situations is tenex rope used for?
pulling and stringing, climbing and rigging
what is the catalog breaking strength of tenex?
11,800 lbs
what are the limitations for synthetic rope?
strands can melt with heat or flame, sharp edges and abrasions under tension
what is considered the strongest wire rope?
improved plow steel
what are the three basic grades of steel wire rope from lowest to highest?
-mild plow steel
-plow steel
-improved plow
in what obvious situation should wire rope be avoided?
when working with energized conductors
what are some problems with use and care of wire rope?
must be kept out of weather, rust can damage on the inside leaving outside looking ok, kinking or bending, broken strands
what can sand and dirt do to ropes?
cut individual fibers (synthetic)
rust (wire rope)
always ______ ______ _________ and ________ standards for care, use, and inspection of rope?
review manufacture recommendations/
OSHA
what is the minimum proper care for ropes?
-clean and dry when stored
-hung in neat coils with no kinks/twists
-remove splinters, thorns, burs, sand and gravel
-avoid contact with chemicals
CBS or catalog breaking strength, is defined as what?
average force in lbs needed to break a rope?
WLL, or working load limit of a rope is the?
max load that should ever be applied
if a rope has a catalog breaking strength, why does it also need a working load limit?
to ensure longevity and integrity
what are some other names for WLL?
safe working load, max load value, rated capacity
the working load limit (WLL) of a rope is _____ or _____ of the catalog breaking strength (CBS).
1/5 or 20%
an arbitrary number used to calculate a ropes working load limit?
design factor
what is dynamic loading?
when a rope is exposed to severe conditions and normal working load limit no longer applies.
what are examples of dynamic loading?
- shock loading
- high temp exposure
- excessive use
- extended periods under load
how do you calculate working load limit?
divide the catalog breaking strength by the design factor
what is the WLL of a rope with a standard design factor of 5 and CBS of 7,000 lbs?
1,400 lbs
what is the weakest point of a rope?
the knot or splice
what is the efficiency rating of a bowline?
65%
what is a bowline used for?
used to make a temporary eye
if a bowline, rated at 65% efficiency, is tied to a rope with 1000 lbs of CBS, when will the rope break?
CBS (1000) x .65 (65%) =650 lbs
what is the efficiency rating of a running bowline?
50%
what is a running bowline commonly used for?
when a choke is needed
what is the efficiency rating of a bowline on a bite?
65%
when is a bowline on a bite used?
when a temporary eye is needed and the available rope is longer than desired
both the ______ and _______________ are easily untied even under heavy strain?
bowline/bowline on a bite
what is the efficiency rating of a clove hitch?
60%
what is the clove hitch used for?
fasten a rope around an object
what is the efficiency rating of a square knot?
60%
what is a sheet bend used for?
joining two different sized ropes temporarily
what is a slip knot used for? when should it not be used?
hoisting tools or materials/under heavy strain
what is a grunt knot used for?
tying to a hand line when a hook is not available
what is a snubbing knot used for?
controlling tension
what is the efficiency rating of a snubbing knot?
50%
used to make a permanent eye in the end of a rope or permanently join 2 ends of same sized rope together?
splice
what is the efficiency rating of a splice?
95%
what is the efficiency rating of a short splice?
90%
_____ are almost as strong as the rope. _______ significantly reduce the strength of a rope?
splices/knots
used to join the ends of to identical ropes together or remove a damaged portion.
short splice
what is a back splice used for?
prevents ends from fraying
how many tucks should be used when back splicing?
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