Problems related to the vapor space in containers
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This post was last edited by Wengu on 2024-9-11 at 15:55. The horizontal vessel has a diameter of 1200 mm and a cylindrical body length of 1.7 meters; the medium used is process water. According to the design parameter table (operating pressure: 0.8 MPa, operating temperature: 40°C), it should be classified as a non-Class I vessel. However, the filling factor indicated is approximately 0.85. Per TSG regulations, since there is a gas phase space inside this vessel and its volume exceeds 0.03 cubic meters, it meets the criteria for a pressure vessel and thus should be classified as a Class I vessel. For other products with similar characteristics, some design institutes classify them as Class I vessels, while others do not; in some cases, the filling factor is simply marked as “/”, thereby classifying such vessels as non-Class I vessels. This seems rather contradictory—so, should such vessels be classified as Class I or non-Class I? All experts are welcome to discuss and provide answers! ! ! !
If the working pressure doesn’t comply with the pressure vessel regulations, then there’s no point even discussing the vapor space
Only when the working pressure exceeds 0.1 MPa can we discuss the various types
Yes, but there is a container with a diameter of 850, an operating pressure of 0.6, and a temperature of 60; it is used for process water, and under these conditions it does not fall within the category of pressure vessels. However, when checking the relevant documents, the officials from the Special Equipment Inspection Agency said that the volume factor needs to be taken into account – if the gas space reaches 0.03 cubic meters, then it should be classified as a pressure vessel. It’s not that the gas space issue is ignored just because it isn’t classified as such; rather, the gas space issue needs to be considered first before determining the classification. That’s why I’m still confused.
Based on the information you provided, this heat transfer oil storage tank has a gas space and its volume exceeds 0.03 cubic meters; therefore, it indeed should be classified in accordance with the standards for pressure vessels. Specifically, whether it needs to be classified as a Class I container mainly depends on the maximum operating pressure designed for the container and other safety technical requirements. Different design institutes may have varying experiences or interpretations of the standards; therefore, they adopt different approaches in actual practice. It is also possible to refer to the handling results of existing similar products as a guide. .
Is 0.8 not greater than 0.1? 1. Setting the filling coefficient serves to prevent overfilling; if the container isn’t completely filled, a gas space is created. When this gas space exceeds 0.03 m³, the first condition is met ； 2. The medium is water; in reality, there is also air present as a medium. Therefore, the mediums in the design should be: water and air. The second condition is thus met ； 3. The pressure is 0.8 MPa. Since the container cannot be completely filled with water, the pressure in the gas phase also reaches 0.8 MPa; thus, the third condition is met ； According to the requirements of TSG 21-2016, this belongs to Category I pressure vessels. But I don’t know what the purpose of this design is, or whether it’s to conceal the weight information when the using unit reports parameters.
This design is actually a huge bug; there is no need at all to set a filling coefficient. If only water is filled and the gas space is not filled to capacity, it is impossible for the pressure to exceed 1 kilogram； If the filling coefficient is maintained and the pressure reaches that level, it is necessary to introduce other gases such as air or nitrogen into the gas phase space, because water at 40°C is in a liquid state. The above applies when the process water does not exceed the standard boiling point; if it exceeds that temperature, it is definitely a pressure vessel.
The drawings from the design institute you uploaded show a value of less than 0.1, so it doesn’t fall into that category; therefore, there’s nothing wrong with the original drawings
I have never uploaded any drawings; stop making things up out of thin air.
The key to the issue is figuring out what gas medium should be used for pressurization and why the pressure needs to be set at 0.8 MPa.