Why is the primary stress under water pressure conditions lower than that under installation conditions?

Thread Content

This post was last edited by My name is Tima on 2022-10-7 at 15:52. I would like to ask why the primary stress under hydraulic loading conditions is lower than that under installation conditions? (1) Water pressure condition HYD: WW+HP. Here, WW includes the weight of the pipeline itself, the weight of the water, and the insulation material, while HP refers to the hydrostatic test pressure (note: it is higher than the operating pressure). Installation condition SUS: W+P1 ； Here, W includes the weight of the pipeline itself, the weight of the fluid, the weight of the insulation, and the operating pressure. (2). The fluid density is less than that of water. (3) The temperature is set to 21 degrees by the software. My question is: (1) Compared to the installation conditions, under water pressure conditions, the temperature remains the same, but the weight is greater and the pressure is also higher. Why is the stress actually lower, and by quite a lot? (2) The allowable stresses for the two are different. I want to know: Which parameters should be checked for hydrostatic testing conditions?