ge section 

 of 4-inch-ID X 

 6-inch-long 

 Pyrex glass pipe 



Figure 17. Experimental sealing and 

 bearing system utilizing 

 an 0-ring interposed 

 between the glass pipe 

 flange and the metal 

 end-closure plate. 



2. Thin (0.023-inch-thick) 

 gaskets made of fiber-reinforced neo- 

 prene (Fairprene 5722A), lubricated 

 with silicone grease, were placed 

 between the glass pipe end flanges 

 and the steel end plates and then 

 compressed by tensioning the tie 

 rods holding the assembly together. 

 A watertight seal was provided by 

 applying room temperature vulcan- 

 izing (RTV) silicone rubber to the 

 joint between the end closure and 

 pipe flange after compressing the 

 seal. (See Figure 20.) 



This bearing— sealing system 

 worked reliably on each of three test 

 assemblies cycled 10 times to 3,000 

 psi, and on one specimen cycled 10 

 times to 3,000 psi and then 10 cycles 

 to 4,000 psi. Two others failed on the 15th and 18th cycles to 4,000 psi 

 after being cycled 10 times to 3,000 psi. This system is considered useful 

 for limited cyclical service with 4-inch-diameter flanged glass pipes to depths 

 of 6,000 feet. The same gasket system was found in previous studies'''^ to 

 perform successfully in cyclic tests on glass domes to depths of 40,000 feet. 



3. The gaskets in this case consisted of 1/8-inch-thick polyimide 

 resin (Vespel SP-1 ) washers fitted into grooves in the steel end plates. These 

 washers were of sufficient width that the glass pipe did not touch the steel 

 end plates. During assembly the watertight seal was provided by applying 

 RTV silicone rubber to the area between the washer and the glass pipe. 

 (See Figure 21.) 



Of the two test assemblies cycled, one failed through cracking during 

 the first cycle at 6,000 psi after 10 cycles at 3,000 psi, 10 cycles at 4,000 psi, 

 and 1 cycles at 5,000 psi. The second test assembly completed 1 cycles 

 each at 3,000 and 4,000 psi, cracking on the first cycle at 5,000 psi. This 

 system is considered useful for limited cyclical service with 4-inch flanged 

 glass pipes to 8,000 feet. 



4. Composite gaskets were made by soft-soldering 1/8-inch-thick 

 copper washers to 1/8-inch-thick steel washers and then facing off the flat 

 surfaces parallel and providing them with a 32-rms finish. The steel faces 

 were then coated with a 0.0025-inch-thick molybdenum disulfide 



20 



