Is the normal-pressure pipeline 0 Mpa, or is it one standard atmosphere?

The Regulations on the Safety Supervision of Special Equipment stipulate it in this manner. A pressure pipeline must meet all three of the following conditions (pressure, medium, and nominal diameter); otherwise, it cannot be considered a pressure pipeline. A pressure pipeline is a tubular device that uses pressure to transport gases or liquids. It refers to pipelines in which the maximum operating pressure is 0.1 MPa (gauge pressure) or higher for gases, liquefied gases, or steam, as well as for liquid media that are flammable, explosive, toxic, corrosive, or have a maximum operating temperature equal to or higher than their standard boiling point, and whose nominal diameter is greater than 25 mm.

The pressure specified in the definition of pressure pipelines is 0.1 Mpa gauge pressure, while the standard atmospheric pressure is 0 Mpa gauge pressure.

First of all, it should be noted that your unit seems a bit confusing. Standard atmospheric pressure is approximately 101.325 kPa (kiloPascals), which is equal to 1 atm (atmosphere), but it is far lower than the 101385 kPa you mentioned. At the same time, this value is only equivalent to 1.01325 MPa, rather than 101.325 MPa as one might think. Then, regarding your question, a \"atmospheric pressure pipeline\" usually refers to a pipeline in which the operating pressure is close to atmospheric pressure (i.e., about 0.1 MPa or 1 atm), but not exactly 0 MPa. As for whether it is a pressure pipeline, generally, whether a pipeline is classified as a “pressure pipeline” depends on its design pressure and size (diameter). In some jurisdictions (for example, according to the relevant Chinese standard GB/T 150-2011), if a pipe has a working pressure greater than 0.1 MPa and an inner diameter exceeding 50 mm, it is classified as a pressure pipe. Therefore, if the pipeline pressure is one standard atmosphere (i.e., 101.325 kPa or 0.1 MPa) and the pipeline diameter is greater than 50 mm, then under these definitions, such a pipeline is generally considered a pressure pipeline. .

It is recommended that the original poster clearly distinguish between “pipes under pressure” and “pressure pipes”; these are two entirely different concepts. Refer to the updated regulations on the supervision of special equipment for more details.

The pressure specified in the definition of pressure pipelines is 0.1 Mpa gauge pressure, while the standard atmospheric pressure is 0 Mpa gauge pressure.

The correct answer on the 4th floor is gauge pressure, not absolute pressure

One standard atmosphere corresponds to a pressure of 101385 kPa??????????????? 101325 Pa