Figure 69. Removal of imploded 15-inch-diameter capsule from the 

 18-inch-diameter pressure vessel. 



Models were tested under long-term loading conditions in hydrostatic 

 pressure vessels specially built for this project. The pressure was raised at a 

 100-psi/min rate to the desired pressure level by pumping tap water into the 

 vessel with pneumatically powered positive displacement pump. When the 

 desired pressure level was reached, the line to the pump was closed. Since 

 the pressure inside the vessel varied from day to day because of variations in 

 room temperature and the progressive contraction of the hull under hydro- 

 static loading, daily pressure corrections were necessary. These pressure 

 corrections were accomplished by opening the valve in the pipe connecting 

 the vessel to the pump and increasing the pressure, or by opening the valve 

 in the drainline and decreasing the pressure. The day-to-day pressure varia- 

 tions were general ly less than 1 psi, although on some occasions they were 

 as large as 70 psi when sudden temperature changes took place in the 

 uninsulated building where the vessels were located. 



The models undergoing the long-term tests were not filled with water 

 prior to placement in the vessel, but were simply vented to the ambient 

 atmosphere. Because of the large buoyancy that the models possess, lead 

 ballast was attached to the bottom plates in the models. This test condition 

 better simulated the loading conditions to which a large-scale capsule will be 



103 



