Anchor Chains 



Two types of 3/4 inch anchor chain, Dilok and welded stud link, 

 were exposed at the depths and for the periods of time shown in Table 

 1, The chain links were covered with layers of loose, flaky rust 

 after each exposure. The layers varied from thin to thick as the 

 time of exposure increased. Destructive testing of the exposed 

 chain links (Table 8) showed no decrease in the breaking loads of 

 the links for periods of exposure of at least 1,064 days. Hence, 

 there was no impairment of the strength of either of the chains. 

 The Dilok links all failed at the bottoms of the sockets where the 

 cross-sectional area of the steel was the smallest. Rust was present 

 in all these broken sockets indicating that sea water had penetrated 

 the joints. Stagnant sea water in these sockets for prolonged periods 

 of time could result in destruction of the links due to the internal 

 stresses created by the formation of corrosion products. 



Wire Rope 



A number of metallic wire ropes were exposed at various depths 

 and for different periods of time as shown in Table 9. These were 

 plow steel, galvanized steel, aluminized steel, stainless steel and 

 90 copper-10 nickel clad stainless steel ropes and cables of different 

 types of construction. 



The first three ropes in Table 9 were for an evaluation of the 

 effect of plastic tape on the corrosion and strength of a conventional 

 wire rope. The breaking strengths were the same after exposure and 

 were in agreement with published nominal values for this type of rope. 

 There was more rust on the inside strands of the degreased rope than 

 on the one in the "as received" (lubricated) condition. For a dis- 

 tance of about 3 feet from the eyes there was considerably more rust 

 underneath the polyethylene tape, than on the degreased rope. About 

 50 percent of the inside strands were rusted at the break in the rope. 

 This test indicates that no corrosion protection is afforded by taping 

 when sea water has access to the interface between the rope and the 

 tape. 



The zinc on the 0.125 inch diameter, 7 x 19 construction, lubri- 

 cated galvanized aircraft cable was completely covered with red rust 

 after 403 days of exposure at a depth of 6,780 feet. In addition, 

 the breaking strength had decreased by 50 percent. 



The amount of zinc remaining on the other five galvanized ropes 

 varied from none in the case of the 0,094 inch diameter, 7x7 cable 



