Some Things Every User Should
Know About Use and Care
of
The following information is NOT a complete discussion of wire rope
or
wire rope slings.
WHAT
FOLLOWS IS A BRIEF OUTLINE
OF
THE
BASIC INFORMATION
REQUIRED
TO
SAFELY USE
WIRE
ROPE AND WIRE ROPE SLINGS.
1.
Wire
rope
WILL
FAIL
IF
WORN
OUT,
OVER-
LOADED, MISUSED, DAMAGED or IMPROPERLY
MAINTAINED.
2. In service, wire rope loses strength and work capability.
Abuse and misuse increase the
rate
of
loss.
3. The NOMINAL STRENGTH, sometimes called CATA-
LOG strength,
of
a wire rope applies ONLY to a NEW,
UNUSED rope.
4.
The
Nominal
Strength
of
a wire
rope
SHOULD
BE
CONSIDERED the straight line pull which will ACTU-
ALLY
BREAK
a new, UNUSED rope.
The
Nominal
Strength
of
a wire rope should NEVER BE USED AS
ITS WORKING LOAD.
5. To detennine the working load
of
a wire rope, the NOMI-
NAL
strength
MUST
BE
REDUCED
by a
DESIGN
FACTOR (fonnerly called a Safety Factor). The Design
Factor will vary depending upon the type of machine and
installation, and the work performed. YOU must deter-
mine the applicable Design Factor for your use.
For
example,
a Design
Factor
of
"5" means
that
the
Nominal Strength
of
the wire rope must be DIVIDED BY
FIVE
to determine the maximum load that can be applied
to the rope system.
Design
Factors
have
been
established
by
OSHA,
by
ANSI, by
AS
ME
and similar government and industrial
organizations.
No wire rope or wire rope sling should ever be installed
or used without full knowledge and consideration
of
the
Design Factor for the application.
6. WIRE ROPES WEAR OUT. The strength
of
a wire rope
begins to decrease when the rope is put in use, and con-
tinues to decrease with each use.
7.
NEVER
OVERLOAD
A
WIRE
ROPE.
This
means
NEVER USE the rope where the load applied to it is
greater than the working load determined by dividing
the
Nominal Strength
of
the rope by the appropriate Design
Factor.
8.
NEVER "SHOCK LOAD" a wire rope. A sudden appli-
cation
of
force or load can cause both visible external
damage and internal damage. There is no practical way to
estimate the force applied by shock loading a rope. The
sUdden release
of
a load can also damage a wire rope.
9. Lubricant
is
applied to the wires and strands
of
a wire
rope when it
is
manufactured. This lubricant
is
depleted
when the rope
is
in service and should be replaced peri-
odically.
10. Regular, periodic INSPECTIONS
of
the wire rope, and
keeping
of
PERMANENT RECORDS SIGNED
BY
A
QUALIFIED
PERSON,
are
REQUIRED
BY
OSHA
FOR
ALMOST
EVERY
WIRE
ROPE
INSTALLA-
TION.
The
purpose
of
inspection is to detennine whether or not a
wire rope
or
wire rope sling may continue to be safely
used on that application. Inspection criteria, including
number and location
of
broken wires, wear and elonga-
tion, have been established by
OSHA, ANSI, ASME and
similar organizations.
IF IN
DOUBT, REPLACE THE ROPE.
An
inspection should include verification that none
of
the
specified
removal
criteria
for this
usage
are
met
by
checking for such things as:
•
•
•
•
•
Surface wear: Normal and unusual.
Broken wires: Number and location.
Reduction in diameter.
Rope stretch (elongation).
Integrity
of
end attachments.
In addition, an inspection should include the condition
of
sheaves, drums and other apparatus with which the rope
makes contact.
11. When a wire rope has been removed from service because it
is no longer suitable for use,
IT MUST NOT BE RE-USED
ON ANOTHER APPLICATION.
12. Every wire rope user should be aware of the fact that each
type of fitting attached
to
a wire rope has a specific efficien-
cy rating which can reduce the working load of the rope
assembly or rope system, and this must be given due consid-
eration
is
detennining the capacity
of
a wire rope system.
13.
Some conditions that can lead
to
problems in a wire rope
system include:
•
Ii>
•
•
•
•
•
Sheaves that are too small, worn or corrugated
cause damage
to
a wire rope.
Broken
wires
mea.'1
a loss of strength.
Kinks pennanently damage a wire rope and must
be avoided.
Wire ropes are damaged
by
knots, and wire ropes
with knots must never be used.
Environmental factors such
as
corrosive conditions
and heat can damage a wire rope.
Lack
of
lubrication can significantly shorten the
useful service life
of
a wire rope.
Contact with electrical wires and the resulting
arcing
will
damage a wire rope.
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