How should the calculated stress be determined for the jacket layer (inner layer) of a jacketed vessel during stress verification?
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If the jacket is under vacuum and the vessel is at positive pressure, how is the calculated stress for the jacket determined? If the jacket is at positive pressure and the vessel is also at positive pressure, how is the calculated stress for the jacket determined? Is the calculated stress for a cylinder the same regardless of external or internal pressure?
What is the pressure retention level for the cylinder? Is it possible to avoid pressure retention, and under what conditions?
This can be calculated in several different ways: it is possible to determine the maximum positive pressure inside the inner cylinder, as well as the negative pressure in the jacket； The inner cylinder is 0, with positive pressure in the jacket ； Both the inner cylinder and the jacket are pressurized simultaneously. It shouldn’t matter whether the stress is positive or negative pressure. If the jacket is under vacuum while the container is at positive pressure, the calculated pressure for the jacket can be obtained by subtracting the negative pressure from the positive pressure, and this value can then be used in the formula to calculate the stress. If the jacket is at positive pressure and the vessel is also at positive pressure, then the calculated pressure for the jacket is positive pressure minus positive pressure, and this value is then used in the formula to calculate the stress.
In other words, the calculated stress is determined based on the calculated pressure, and it’s sufficient to obtain the correct value for that pressure; there’s no need to consider whether it’s internal or external pressure. If the inner cylinder has already passed the jacket hydrostatic test during the verification hydrostatic test, does that mean there is no need to maintain pressure on the inner cylinder?