DOE-STD-1090-96, DOE Standard Hoisting and Rigging Manual ...

DOE-STD-I090-96 (Rev-I)11.2 WIRE ROPE11.2.1 Wire-Rope LaysaIn a right-lay rope, the strands twist to theright around the core like a conventional screwthread; in a left-lay rope, the strands twist to theleft.b. A rope has a lang lay when the strands andthe individual wires have the same lay direction.When the strands and the wires have an oppositelay direction, the rope has a regular lay.c. A standard wire rope, unless otherwisestated, is understood to beright regular lay. Withfew exceptions, all wire rope is made right lay.Left-lay rope is a special-purpose rope.d. Figure 11-2 shows ropes with right and leftlays combined with regular and lang lays.e. Lay length is the lengthwise distancemeasured along a wire rope in which a strandmakes one complete revolution about therope'saxis.11.2.2 Wire-Rope Coresa. Wire rope consists ofmultistrand metalwires wrapped around a suitable core material.Wire-rope cores are carefully designed and mustbeprecisely manufactured to close tolerances toensure a perfect fit in the rope. The most commontypes ofcores include the following (see Figure11-3): .1. Fiber Core (FC) or Sisal Core-Sisalanna is the most common fiber that is used inthe manufacture ofwire-'rope cores. In smallerropes, cotton and jute are sometimes used for thecore.2. Independent Wire-Rope Core(IWRC)-The primary function ofthe core is toprovide adequate support for the strands. As thename implies, an IWRC is a separatesmall-diameter wire rope that is used as the corefor a larger wire rope. When severe crushing orflattening ofthe rope is encountered, an IWRC isusually specified.3. Strand Core-This type ofcore has a singlestrand used as the core. This type is generallyconfined to the smaller ropes as a substitute forIWRC. The strand core mayor may not have thesame cross section as the surrounding strands.Right Regular LayLeft Regular LayRight Lang LayLeft Lang LayFigure 11-2. Wire-rope lays.••Fiber or Sisal CoreIndependent Wire-Rope CoreStrand CoreFigure 11-3. Wire-rope cores.Chapter 11Wire Rope and Slings 11-4