Why is the design pressure sometimes very different from the work pressure?
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Why is the design pressure sometimes very different from the work pressure? Is there any evidence? For example, a 1000L closed ammonia storage tank with a design pressure of 0.9 and an operating pressure of 0.4
bg14.jpg Generally, when the pressure exceeds 1.05 to 1.1 times the value, the possible reasons are: 1. The maximum allowable operating pressure is specified based on the airtightness test and safety valve in place； 2. It is the customer who requests an increase (the same goes for temperature; water at dozens of degrees is common, yet the design temperature is set at over 100 degrees) ； 3. It is affected by temperature (see figure: saturated vapor pressure of water) ； 4. Factors related to the medium itself: I have not been involved in the design related to this aspect, so I am unaware of its detailed characteristics. 5. Special conditions such as sudden or instantaneous pressure increases during use. 6. Other factors......
It’s like this: you only need a bed of 2 square meters to sleep in, but you buy a large house covering 150 square meters; P
In some cases, the design pressure also takes into account the pressure of the entire piping system.
Sometimes customers think that the higher the design pressure, the safer the equipment will be to use. For example, in the case of a device where the operating pressure is 10 MPa and the design pressure is 11.5 MPa, it seems reasonable, right? But the actual pressure used by the customer is less than 6 MPa, yet it was forced to be classified as a Class III container: lol
It’s actually a waste. Normally, the design commission submitted by users includes a work pressure factor, and the design pressure should be slightly higher than this work pressure; for example, if the work pressure is 1.0 Mpa, then a design pressure of 1.2 or even 1.5 would be sufficient.
Sometimes it is necessary to consider the pressure of the entire piping system
Yes, sometimes the design requirements for the equipment are standardized according to the conditions of this system