Hydrostatic Pressure Effects on 1/4 Inch Polypropylene Line.
NAVAL POSTGRADUATE SCHOOL MONTEREY CALIF
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The effects of hydrostatic pressure on the mechanical properties of 14 inch polypropylene line are investigated. The line is exposed to hydrostatic pressures of 5,000 and 10,000 psi for periods of 6, 12, and 24 hours, respectively. Upon completion of the pressurization period, the line is removed from the pressure vessel and its ultimate tensile strength recorded and compared to that of the line before pressurization. There is an increase in the tensile strength of the line as pressure increase and time progress, with a maximum increase of 3.1 percent occurring after pressurization at 10,000 psi for 12 hours and at 5,000 psi for 24 hours. Secondly, there is no measurable difference in the relative elongation of the line after pressurization as compared to that before pressurization. The mode of failure is investigated by testing individual line fibers. Microscopic observation after failure shows no discernible difference between the mode of failure before and after pressurization. In each case, the fibers present a somewhat jagged edge and the outer portions of the fiber appear to have peeled back. Author-PL