STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

588 Drilling and Well Completions
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100 0 5 IO 15
SHEAVE-
Figure 4-70. Efficiencies of
stresses only) [Ill.
20 25 30 35 40 45 50
ROPE DIAMETER RATIO D/d
wire ropes bent around stationary sheaves (static
should be employed between the drum and the fast line sheave to reduce
vibration and to keep the drilling line from rubbing against the derrick.
Martensite is a hard, nonductile microconstituent formed when steel is heated
above its critical temperature and cooled rapidly. In the case of steel of the
composition conventionally used for rope wire, martensite can be formed if the
wire surface is heated to a temperature near or somewhat in excess of 1400°F
(76OoC), and then cooled at a comparatively rapid rate. The presence of a
martensite film at the surface of the outer wires of a rope that has been in
service is evidence that sufficient frictional heat has been generated on the
crown of the rope wires to momentarily raise the wire surface temperature to
a point above the critical temperature range of the steel. The heated surface is
then rapidly cooled by the adjacent cold metal within the wire and the rope
structure, and an effective quenching results.