22 Hooked on SER VICE Construction Identification of Steel Wire Rope Wire ropes are identified primarily by construction The number of strands and the number and geometric arrangement of wires within the strands make up the wire rope construction The more common constructions are sho wn belo w Note tha t each construction can ha ve more wires than sho wn but the geometr y remains the same F o r example there can be twoopera t ion ropes ha ving more than 19 wires there can be Seale ropes ha ving more than 19 wires there can be W a rrington ropes ha ving more than 19 wires and there can be F iller Wire types ha ving more or less than 25 wires Here are the basic constructions Each of the above possesses unique characteristics which must be considered when selecting rope or strand for a j o b T h e specific geometric construction selected depends on the destructive factors present on the job Wir e Rope Construction The most common factors abrasion and fa tigue crea te conflicting requirements Small more numerous outer wires resist fa tigue but are easily worn through by abrasion Larger outer wires ha ve superior abrasion resistance but are more quickly broken by bending and flexing The differ ence in outer wire size is seen between the 6 x 19 Seale and 6 x 25 F iller Wire constructions The nine outer wires in the Seale strands are c l early larger than the 12 outer wires in the F iller Wire strands Other destructive factors must be considered peening corrosion hea t crushing and shock loads Classification Each wire rope construction falls within a c l assifica tion Classifica tions are identified by the number of strands and nominal number of wires The actual number of wires must fall within a range specified for the given c l ass F o r exam ple ropes within the 6 x 19 c l ass contain 6 strands made up of 15 through 26 wires of which no more than 12 are o u t s i d e w i r e s T h e 6 x 19 Seale and 6 x 25 F iller Wire con structions therefore a r e b o t h w i t hin this c l ass The more common c l assifica tions are 6 x 7 6 x 19 6 x 37 8 x 19 and 19 x 7 Cor e The sole purpose of the core of a rope is to support the strands under normal bending and loading conditions The three most common types are F iber Core FC Independent Wire Rope Core IWRC and Wire Strand Core WSC The bottom ro w of constructions are sho wn with 7 x 7 IWRCs where the 6 x 19 2opera t ion and 6 x 19 W a rrington con structions contain fiber cores The 7 x 7 construction contains a 1 x 7 WSC and the 7 x 19 2opera t ion construction contains a 1 x 19 WSC Almost all constructions can ha ve either of the three types of core Na tural or synthetic fiber rope cores can be used a t loads up to about 25 of the nominal strength and a t tempera tures up to 200F At higher loads and tempera tures the strands will lose support and either a WSC or an IWRC must be used Grea ter support is also needed for rope opera t ing over small diameter shea ves and drums under hea vy loads Gr ade The grade of rope depends on the strength requirements of the job Grades commonly used inc lude T r action Steel TS Improved Plo w Steel IPS Extra Improved Plo w Steel EIP and Double Extra Improved Plo w Steel EEIP These grades are most often bright or uncoa ted but the wires may be galvanized zinc coa ted Wire galvanized a t finished size is usually 10 lo wer in strength than bright wire where dra wn galvanized wire has the same strength Other wire types commonly used inc lude Galvanized Aircraft GAC and various grades of stainless steel and bronze La y An important considera tion in wire rope construction is the way the wires ha ve been laid to form strands and the way the strands ha ve been laid around the core Lay is c l assified by both direction and type The lay direction of the wires within a strand and of the strands within a 1 x 7 7 x 7 1 x 19 7 x 19 6 x 19 2 Operation Fiber Core 6 x 25 Filler Wire 6 x 36 W a rrington Seale 6 x 41 W a rrington Seale 7 x 7 IWRC 6 x 43 Filler Wire 7 x 7 IWRC 6 x 19 W a rrington 6 x 19 Seale 6 x 26 W a rrington Seale