Is external pressure calculation done without considering the core? In the external pressure formula, the value of σ0 is limited to 0.9Rel; does this indicate that instability occurs at the yield point?
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Dear teachers, today I saw that the formula for external pressure calculation is B/D0/δe, and the formula for the maximum allowable working pressure is =2*δe*t*Φ/(Di+δe). In both formulas, the value used for thickness is δe – the effective thickness. The maximum allowable operating pressure is determined by taking into account all the thicknesses remaining after deducting the corrosion allowance and any negative deviations – in other words, the effective thickness – to calculate the membrane stress, thereby determining the maximum internal pressure that the equipment can withstand. The idea here is to consider the entire thickness available, aside from the amount reserved for corrosion, in order to find out the maximum internal pressure the equipment can handle. As for the formula for calculating external pressure, which is B/D0/δe, it also uses δe in its calculation; does this mean it serves the same purpose, namely to determine the maximum external pressure that the equipment can withstand without losing stability? Are the formula for calculating external pressure and the maximum allowable working pressure equivalent in concept? Both are used to determine the maximum pressure that a material of a given thickness can withstand, with the difference being that one relates to internal pressure and the other to external pressure
And D0/δe in the external pressure calculation formula
The external pressure calculation usually does not include the nuclear part, considering only the structural parts that are subjected to external pressure. Taking σ0 at 0.9Rel indeed means that instability is defined by yield. The effective thickness in both formulas refers to the thickness after deducting the corrosion allowance and negative deviations; this thickness is used to calculate the maximum pressure that can be tolerated. The external pressure calculation formula is used to determine the maximum external pressure that a device can withstand without losing stability. The external pressure formula and the maximum allowable working pressure formula are indeed conceptually equivalent, as both are used to calculate the ultimate pressure that a material can withstand at a given thickness; the difference lies in the fact that one is used to calculate internal pressure while the other is used to calculate external pressure. .
The internal pressure calculation is based on theoretical calculations, and the device tends to become circular when subjected to internal pressure; the external pressure calculation is based on experimental data, and even if the calculations are successful, instability can still occur if the cylinder is not round enough during manufacturing. As for the maximum allowable operating pressure and the external pressure calculation, I believe they are both determined through reverse calculations; the effective thickness for the maximum allowable operating pressure is calculated based on the nominal thickness, whereas when calculating the external pressure, the effective thickness can only be estimated.
Hello, may I ask: is the external pressure calculation based on experimental results? Specifically, are the values of strain coefficient A and stress coefficient B used in the external pressure calculation as specified in GB/T150, as well as the curves related to D0/δe and L/D0, all derived from experimental data?
And D0/δe in the external pressure calculation formula
Hello, may I ask: is the external pressure calculation based on experimental results? Specifically, are the values of strain coefficient A and stress coefficient B used in the external pressure calculation as specified in GB/T150, as well as the curves related to D0/δe and L/D0, all derived from experimental data?