Axial Seal 



Radial Seal 



Figure A-10. Typical end-closure seals. 



Recommendation. It is recommended that experimental investigations 

 be initiated for development of an improved self-energizing radial seal suited for 

 10-foot-diameter vessels and 10,000-psi operational pressure. 



IMPLOSION LOADING OF PRESSURE VESSELS 



Past experience at laboratories equipped with internal pressure test 

 vessels* has shown that when implosion of models occurs, a severe shock wave 

 is generated which causes the test vessel to be moved laterally or vertically, 

 damaging in the process auxiliary equipment attached rigidly to the pressure 

 chamber. Although there is no record of a pressure vessel rupturing because 

 of an implosion inside of it, this can be attributed in a large extent to the high 

 safety factor of 4 used under the ASME code, the very ductile materials employed, 

 and the low hydrostatic pressures involved in the testing. With the present 

 trend in test vessel design aimed at larger vessels, higher working pressures, 

 materials with higher yield-points but lower ductility, and reduced safety factors, 

 it is only a matter of time before a catastrophic failure of a vessel will occur 

 because of an imploding test object. 



* For example, the Southwest Research Institute, San Antonio, Texas; the Ordnance 

 Research Laboratory, State College, Pennsylvania; the Navy Ordnance Laboratory, 

 White Oaks, Maryland; the Navy Underwater Test Station, Newport, Rhode Island; 

 the David Taylor Model Basin, Carderock, Maryland. 



59 



