improvements were also made in the internal fuel piping, 

 such as replacement of bad sections and improvement of 

 low point drains. 



NITROGEN INERTING SYSTEM 



This system provides an inert atmosphere inside the 

 float prior and subsequent to fueling and defueling operations. 

 It is so constructed that nitrogen gas (N 2 ) under pressure, 

 is admitted to the float through the high point vent holes in 

 each tank. In the case of fueling, the rising liquid level 

 displaces nitrogen preventing creation of dangerous explo- 

 sive vapor concentrations within the float. In the defuel- 

 ing operation, as the liquid level decreases, the empty space 

 created is filled by nitrogen, also reducing explosive vapor 

 concentration within the float. The flow of the nitrogen is 

 manually regulated from a central control point topside. 

 The nitrogen system and improved fuel handling procedures 

 for the bathyscaph were the result of NEL requested con- 

 sultation by the aircraft carrier aviation gas specialists 

 from the San Francisco Naval Shipyard and the Mare Island 

 Naval Shipyard. 3 



3. SUPERSTRUCTURE 



The present superstructure design on TRIESTE resulted 

 from the difficult working conditions experienced by the 

 TRIESTE crew during the sea operations off the island of 

 Guam. In the past, TRIESTE had only a 20- inch freeboard 

 which was actually the top of the float. Working on top of 

 this rolling cylinder at sea posed considerable problems 

 for the topside crew in making their post-towing inspections 

 and preparations for the dives. In fact, it was not unusual 

 for crew members to be swept over the side. With these 

 experiences in mind, a light-weight free flooding super- 

 structure was designed for TRIESTE. This structure is 

 made of stainless steel supporting members, with Fiber- 

 glas side panels and aluminum gratings at the top. The 

 superstructure covers about 90 per cent of the length of 

 the float, is 6 feet wide, and stands approximately 18 inches 



3 San Francisco Naval Shipyard Report, Operational Safety 

 for the Gasoline System on Bathyscaph TRIESTE, by A. C. 

 Wong, 2 3 April 1961 



34 



