inelastic region. It was not possible to distinguish 

 between spurts of activity and the activity just prior 

 to failure. 



(3) Pressure - The technician, who pressurized the speci- 

 men, closely watched pressure gages during the test. 

 A pause in the rate of movement of a pressure gage 

 needle would indicate imminent failure. For several of 

 the tests there was no pause in needle movement; and 

 for the tests with a pause, time was not sufficient to 

 relay a message. 



Upon removal, the specimens from the pressure vessel were 

 inspected, photographed, and sketched. Fragments of concrete from 

 failure zone sections were salvaged and pieced together for closer 

 inspection of the failure zone. 



It was at this stage that wall thickness measurements were made. 

 The specimen was broken up, and the thickness of the pieces was 

 measured with a micrometer. In this manner, numerous and accurate 

 measurements of wall thicknesses were obtained. 



SPECIMEN GEOMETRY 



A summary of the specimen geometry is given in Table B-1. Data 

 on maximum and minimum wall thicknesses are presented. Also, con- 

 struction out-of-roundness data at the flat-spot locations are given. 

 Typically, the minimum wall thickness coincided with the flat-spot 

 location because this occurred at the outer mold seams. Table B-2 

 gives a digest of the out-of-roundness parameters. This presentation 

 of data, however, is not truly descriptive of the out-of- round shape. 

 Figure B-5 shows a cross- section at an elevation of 50 inches from the 

 bottom, 4 = 0.4, of specimen 2-3. The initial out-of- round shape for 

 the outer and inner mold are shown, using an exaggerated displacement 



50 



