WIRE ROPE 



Stainless steel wire ropes of different diameters, types of con- 

 struction and compositions were exposed at the 2,500- and 6,000-foot 

 depths. These wire ropes and their conditions after exposure are 

 given in Table 8. 



The. AISI Type 304 lubricated stainless steel wire ropes in diame- 

 ters less than 0.250 inch were all seriously corroded within 6 months 

 or 1 year of exposure at the 6, 000- foot depth. During 1 year of expo- 

 sure at the 6,000-foot depth they lost a minimum of 86 percent of their 

 origianl breaking loads. The types of corrosion observed in all cases 

 were pitting, tunneling, internal wire corrosion or crevice corrosion, 

 and in most cases all types. The corrosion caused the individual wires 

 to break in many cases. 



There were only a few rust stains and no broken wires on the AISI 

 Type 304 wire ropes after 1 year of exposure at the 6,000-foot depth 

 and after 6 months of exposure at the 2,500-foot depth in the 0.25-inch 

 and larger diameter ropes. 



AISI Type 316 stainless steel wire rope which was stressed at 20 

 percent (350 lb) of its breaking strength during exposure for 3 years 

 at the 6,000-foot depth lost 41 percent of its breaking strength due to 

 the internal wires being broken at corrosion pits. 



An 18Cr-14Mn stainless steel wire rope stressed at 20 percent 

 (250 lb) of its original breaking strength did not lose any strength 

 after 3 years of exposure at the 6,000-foot depth, even though there 

 were many broken wires, both external and internal, caused by pitting 

 and crevice corrosion. 



Stress relieving after stranding of AISI Type 304 stainless steel 

 wire rope was ineffective with regard to the corrosion resistance of 

 the rope. 



The addition of vanadium (V) and nitrogen (N) did not improve the 

 corrosion resistance of the conventional stainless steel rope (Type 

 304). 



The corrosion resistance of the conventional AISI Type 304 stain- 

 less steel was improved by the addition of other alloying elements in 

 the following order, from most to least: 



(a) Molybdenum (Mo) , silicon (Si) and nitrogen (N) 



(b) Molybdenum (Mo) and copper (Cu) 



(c) Silicon (Si) 



Cladding AISI Type 304 stainless steel wire rope with an alloy con- 

 sisting of 90 percent Cu - 10 percent Ni protected the rope as long as 

 the cladding material remained on the wires. A . 3-mil thick clad 

 layer was completely depleted on the outside wires within 1 year of 

 exposure at a depth of 2,500 feet and they were covered with a thin film 



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