Upon completion of initial anneal, the viewports were machined to final 

 dimensions and annealed again. The viewports were polished to an optical 

 finish before testing to facilitate post-test observations of possible cracks. 



Figure B-3. Experimental test setup. 



All minor diameters of the viewports were designed larger than the 

 penetrations in the pressure vessel to elevate the viewport in its seat in order 

 to avoid the stress concentration at the break of the conical surface. 



Because the test occurred over such a length of time, it was necessary 

 to insure accuracy of results. Therefore, two viewports of the same dimen- 

 sions were tested at the same time to provide redundancy to the test. 



TEST PROCEDURE 



The conical surfaces of the viewports were first coated with Dow 

 Corning No. 4 silicone grease, a lubricant which will not attack the acrylic 

 plastic. After the six viewports were placed in the three vessels, the vessels 

 were filled with tap water. Initially, the pressure was raised to 2,000 psi and 

 quickly returned to psi. This procedure seated the viewports, squeezed out 

 a majority of the excess grease, and allowed the dial indicators to be zeroed. 

 Subsequently, the pressure and temperature were changed simultaneously 



45 



