SPLICE METHODS 

 First Technique 



The first technique utilizes two 2-inch (5-cm) pieces of Tygon 

 tubing, a nylon butt-crimp connector, two plastic ties (ICO/Rally), and 

 a tube of 3140 RTV (see Figure 1A) . The 3140 RTV, a Dow Corning product, 

 is a silicone base rubber with a noncorrosive alcohol solvent that 

 vulcanizes at room temperature. To prepare the splice, the Tygon tubing 

 is cemented to each end of the butt connector . This is accomplished as 

 follows. A small amount of RTV is smeared on the outer nylon surface 

 of the butt and the inside surface of the Tygon tubing for a distance 

 of approximately 3/16 inch (4.7 mm) to 1/4 inch (6 mm). Using only the 

 fingers, the Tygon tubing is slipped over the end of the nylon butt. 

 Then a small amount of RTV is applied to form a head on the edge of the 

 tubing to bond to the nylon. This piece is then put aside for 24 hours 

 to allow the RTV to cure. After curing, the Tygon tubing (held in a 

 vertical position) is slipped over the special applicator supplied with 

 the tube of RTV. The RTV is slowly forced into the splice butt, allowing 

 any air bubbles formed to rise to the surface. The ends are then sealed 

 with the plastic ties, and the splice is stored until needed. 



When the splice is to be used, the ends, including the plastic 

 ties used for sealing, are cut off by the divers, and the conductors 

 (prepared as would be done for any normal crimp splice) are carefully 

 placed through the RTV inside the Tygon tubing and pushed firmly into 

 the butt connector. Holding both parts in place, new plastic ties are 

 applied near the ends to hold the two pieces in place and to keep the 

 RTV from running out. The butt is then crimped. Most normal tie rap and 

 crimping equipment can be used repeatedly under water by divers as long 

 as care is taken to clean the equipment after use. Since the RTV has 

 an alcohol base, it cures underwater. The completed splice is shown in 

 Figure 1B. 



This simple technique does not violate any of the five rules. The 

 RTV remains flexible after curing and, therefore, allows the completed 

 splice to maintain a zero-pressure gradient. The RTV also provides a 

 wiping action to remove any seawater from the conductors. In early splice 

 attempts with techniques where wiping action was not provided, corrosion 

 failure was experienced when power was transmitted through the conductor. 

 Visual observations made of the failed splices indicated that a two- 

 stage mechanism could be responsible for the failures. First, entrapped 

 seawater at the electrical junctions causes a small amount of corrosion 

 which results in the loss of the metal-to-metal electron path in the 

 connection, but does not result in a loss of continuity because of the 

 conductivity of the entrapped seawater. Second, gross corrosion results 

 from the electric current passing through the seawater electrolyte, 

 which is responsible for the ultimate failure of the splice. 



