On the causes of shell deformation in tank car boilers for viscous petroleum products

Purpose: the existing problem of detected damages to tank car boilers during operation due to loss of stability requires new approaches to both theoretical and practical assessment of possible causes of such damages. The evaluation of the combination of various factors, including the impact of shape deviation of the boiler during its manufacture, on the possibility of loss of stability during operation is of particular relevance. Method: to determine the causes of boiler deformation, stability calculations were performed on the boiler. All calculations were conducted for actual thicknesses determined by measurement and thickness gauging.A tank car model with the minimum measured thicknesses was selected for modeling. Calculations were carried out under the action of the standard external pressure value and under excessive external pressure values. Results: stability calculations of the boiler with the actually measured thicknesses under the influence of external excess pressure showed that loss of stability in the boiler: without shape deviation under the action of the standard external excess pressure of 40 kPa was not detected; with local defects from welding under the action of the standard external excess pressure of 40 kPa was not detected; without local welding defects but with a global shape deviation of the boiler under the action of external excess pressure of 40 kPa is possible with a relative ovality of about 2.7 %; without global shape deviation of the boiler, it is possible under the influence of excessive external pressure of 79 kPa and above. Practical significance: possible causes of boiler instability during operation were identified. The cause of boiler instability may be a global shape deviation of the boiler with a relative ovality of about 2.7 %; the effect of excessive external pressure of 79 kPa and above, which is possible due to a violation of the tank car unloading process; a combination of global shape deviation of the boiler and the effect of excessive external pressure due to a violation of the tank car unloading process.