The Research Of Crack Resistance And Safety Reliability On Pump Head

Pump head was one dependent part of the oil exploration equipments, which wasendured the pressure. When the pump head was worked, the cracks and flaws wereappeared in the internal cylinder because of the poor working conditions, such as lowtemperature, high pressure, corrosive media and circular load. The safety assessment onpump head was very important in actual production.In this paper, as the standards of Structural Integrity Assessment Procedure (SINTAP)and Guide on methods for assessing the acceptability of flaws in metallic structures(BS7910-2005) to the guide, at the base of the study of materials’ properties, the safestandard of assessing welded joints were applied to assess the safety of the materials.Firstly, at the room temperature and low temperature, the tensile test and the impacttest were tested so as to gain the basical properties of the materials, the curves of turestress-strain were received from the curve of engineering stress-strain, which were used todetermine the third assessment curves. At the room temperature, the three-point bendspecimen was devised according to the standard of GB/T4161-2007, and then the test ofcrack tip opening displacement (CTOD) was measured by the standard of GB/T2358-1994.The curve about load and displacement was got from the CTOD test, the maximum loadand displacement were obtained from the curve, and then the value of CTOD wascalculated, which were used to illustrate the fracture toughness of materials.Secondly, the actual work situation of the pump head was considered, and theinternal actual stress of the pump head was not measured when it was worked, so thenumerical simulation about pump head was applied by the use of Ansys software, and themaximum internal stress was obtained when the pump head worked at the maximum loadand used to the process of safety assessment. At the same time, the stress of out surfaceof pump head was tested at the maximum load. The trends of the measurement results andthe simulation results were compared, and the accuracy of results on the internal actualstress by numerical simulation was certified.Lastly, according to the safe standards of SINTAP and BS7910-2005, the assessment curves were chose and determined, and the assessment points were calculated.The assessment points were putted into the assessment curves, and the maximumassessment point was gained, and the maximum sizes of the crack were got from theprocess of assessment points.