Which loads should be considered during design?
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The following loads should be considered during design: a) internal pressure, external pressure, or maximum pressure difference； b) Hydrostatic pressure of the liquid column: this can be ignored when it is less than 5% of the design pressure ； When necessary, the following loads should also be considered: c) the weight of the container itself (including its contents and packing), as well as the weight load of the medium contained within it under normal operating conditions or during pressure testing ； d) Gravitational loads on auxiliary equipment, insulation materials, linings, pipes, escalators, platforms, etc ； e) Wind load, **load, snow load ； f) Reaction forces from supports, base rings, lugs, and other types of supporting elements ； g) Forces acting on connecting pipes and other components ； h) Forces resulting from different temperature gradients or amounts of thermal expansion ； i) Impact loads, including those caused by sudden pressure fluctuations and the reaction forces resulting from fluid impact, etc ； j) Forces during transportation or lifting. Anything else?
Our university textbooks mention long-term loads, short-term loads, and additional loads. Long-term loads include design pressure, internal and external pressures, the weight of the container itself, and the weight of any attachments. Short-term loads include snow, wind, **loads, and the weight of water when the container is filled with water». Additional loads refer to those generated by gravity acting on attachments mounted on horizontal tanks at heights of up to 10 meters
I think there is also alternating loading, namely the situation where a container is pressurized for a period of time and then depressurized for another period; such alternating loading seems to be something that is often taken into account in stress analysis and design. It is rarely considered in conventional container design, but this type of loading does exist. I hope everyone will communicate more.
This post was last edited by bestleemh on 2011-5-23 15:37. Many different combinations of the above loadings are possible; the designer must select the most probable combination of simultaneous loads for an economical and safe design. (What various combinations of the loads mentioned above are possible?)； The designer should select the combination of loads most likely to occur simultaneously, with the aim of economic and safe design. It is standard engineering practice that all vessels and their supports must be designed and constructed to resist the effects of the following combinations of design loads without exceeding the design limit stresses. （It is standard practice in engineering to ensure that all containers and their supports are designed and built in such a way as to withstand the combined effects of the various design loads, without exceeding the designated stress limits.） ) In all combined loading scenarios, it is not necessary to assume that wind and seismic loads occur simultaneously; when a vessel is designed to withstand both wind and seismic forces, only the load that results in higher stresses needs to be taken into consideration. （In all cases of combined loads, wind loads and seismic loads should not be assumed to exist at the same time, and when a vessel is designed to handle both types of loads, only the one that generates greater stresses needs to be considered.） 1. The erection (empty) design condition takes into account the dead load of the vessel in its erected (empty) state, with full effects from wind or earthquakes. 2. The operating design condition includes the design pressure plus any static liquid head, the dead load of the vessel itself during operation, wind or earthquake loads, as well as any other operational stresses such as vibration, impact, and thermal loads. 3. For hydrostatic tests conducted with the vessel in a horizontal position, the design condition consists only of the hydrostatic test pressure plus the weight of the vessel used for the test. In case of field tests carried out at the actual location, the design condition includes the test pressure plus the static head of the test fluid, along with the vessel’s dead load under operational conditions; wind or earthquake loads need not be considered. All insulation or internal refractory materials are removed during such tests. 4. The short-time (overload) design condition includes the operating design conditions plus any effects resulting from short-term overloads or emergency start-up/shutdown operations, which can lead to increased design loads. At start-up, it is assumed that the vessel is cold while the connected pipelines are hot; wind or earthquake loads need not be considered. The above paragraphs are taken from Henry H. Bednar’s “Pressure Vessel Design Handbook”.