Horizontal vessel axial stress verification conditions
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Dear experts, NB/T47042-2014 stipulates the axial stress verification working conditions. The operating conditions (containing materials) are divided into internal pressure design pressurized and unpressurized, external pressure designed pressurized and unpressurized conditions. Does it mean that when checking the tensile stress, if the container is designed with internal pressure, the axial stress should be calculated when pressurized, and if the container is designed with external pressure, the axial stress should be calculated when unpressurized.； When checking the compressive stress, if the vessel is designed for internal pressure, the axial stress should be calculated when it is not pressurized. If the vessel is designed for external pressure, the axial stress should be calculated when it is pressurized?
Please tell me under what operating conditions will the medium be filled but there will be no pressure? Is this phenomenon common, or does it only occur on special occasions?
This post was last edited by wanlirn on 2018-7-8 16:59 Chemical equipment will inevitably stop.
Your understanding is correct. Please refer to Ding Bomin's "ASME VIII Pressure Vessel Code Analysis" P244. When internal pressure acts, at the mid-span section, there is always tensile stress at the bottom, and tensile or compressive stress may appear at the top. When no pressure is applied, that is, when P=0, the compressive stress at the top may be the largest. When internal pressure acts, the saddle section always has tensile stress at the top, and tensile or compressive stress may appear at the bottom. When there is no pressure, that is, P=0, the compressive stress at the bottom may be the largest. The conclusion under external pressure is opposite to that under internal pressure.
Parking will require a process. During this process, pressure, temperature, and liquid level may change. If you want to describe the load conditions clearly, it will still take some trouble. Usually it is not fatigue equipment, and such detailed load conditions are not given. Is this condition set in the horizontal vessel calibration calculation really universal?
Everyone can understand the reason. But this kind of load condition does not necessarily exist. For example, in a liquefied gas storage tank, as long as it contains the medium, there will be pressure, and there will be no unpressurized situation.
This post was last edited by wanlirn on 2018-7-10 18:36
Please give some typical examples.