Designing and Optimizing the Parameters for Borehole Logging Probe to Sustain External Pressure of 50 kg/cm 2

External hydrostatic pressure or buckling pressure is an important consideration for designing and fabrication of borehole logging probes and in many other industrial applications. These tubes (probes) host wide range of electromechanical devices that are lowered into the boreholes to probe the earth and ocean layers to understand their physio-chemical properties and evaluate for natural resources. Hydrostatic pressure in the boreholes increases at 1 kg/cm² for every 10 meter increase in the depth. Therefore depending upon the water column in the area, it is observed that in a normal 500 meters borehole, it may vary from 0 to 45 kg/cm². These logging probes have to withstand and safe guard all the instruments that are arranged inside. In the present study the collapse pressure for copper, brass and stainless steel tubes of 0.6 mm thickness have been theoretically calculated as 18.13, 37.33 and 55.71 kg/sq.cm; for 1.6 mm thickness as 47.59, 98.43 and 146.24 kg/sq.cm. respectively. FEA analysis on the tubes of these materials resulted in similar values. Experiments were carried out in a pressure vessel creating a uniform hydrostatic pressure up to 50 kg/sq.cm. simulating the borehole conditions. As anticipated the copper and brass tubes of 0.6 mm thick collapsed at 20 and 23 kg/sq.cm pressure and the stainless steel tube with stood beyond 50 kg/sq.cm. The thicker brass and copper tubes of 1.6 mm with stood the hydrostatic pressure beyond 50 kg/sq.cm. Therefore the brass tube of 1.6 mm thickness and 600 mm length is ideally suitable for construction of logging probes which has good engineering, physicochemical properties and cost effective and can replace the imported tubes.