Selection of pressure and temperature ratings for HG/T20592 flanges
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The equipment is made of 304 material, with a working pressure of 3.5 MPa, a design pressure of 5 MPa, a hydrostatic test pressure of 8 MPa, a working temperature of 300°C, and a design temperature of 400°C. A socket flange is to be selected; a long-neck butt-weld flange (WN) according to standard 20592 with PN63 rating and a flange size of DN20 is planned to be used. According to the table, at an operating temperature of 300°C, the maximum allowable operating pressure (gauge pressure) for 2C1 is 35.8 bar. Slightly higher than the operating pressure of 3.5 MPa – is this acceptable?
According to the HG/T20592 standard, the maximum allowable operating pressure (gauge pressure) for 2C1 is 35.8 bar, which is approximately 3.58 MPa when converted to megapascals; this value is slightly higher than the operating pressure of 3.5 MPa for the equipment. Therefore, it is acceptable to use the 20592 standard PN63 long-neck butt weld flange. It should be noted, however, that in actual use, the equipment should be installed and operated at a design pressure of 5 MPa to ensure its safety and reliability. .
This post was last edited by 311yj on 2023-4-14 at 20:55. Hello, I specialize in the design and manufacturing of containers, so I’m not very familiar with their installation and usage. Therefore, I’m not quite sure what you mean by “they should be installed and used at a design pressure of 5 MPa in actual use.” Could you please explain it in more detail? Thank you
For this operating condition, a design pressure of 5MPA is recommended; the presence of temperature creep will **reduce** the safety level to 3.58MPA
This post was last edited by AtlantisH on 2023-4-15 at 10:15. Flanges should be selected according to the design conditions; otherwise, what’s the use of the design pressure and design temperature? Whether it is a container or a pipeline, the pressure-bearing capacity of all pressure-bearing components on it must not be lower than that under design conditions. For suggestions related to pressure vessels, please post in the Static Equipment module under the Equipment section; process engineers may not be responsible for handling pressure vessels.
According to 20592, it should be PN64; should the pressure rating be increased?
How is that possible? The design pressure is 5 MPa. The pressure rating is determined based on the design pressure, not the operating pressure; there is a difference of 1.5 MPa between the two
Personally, I think it is necessary to consider the design pressure and design temperature; therefore, choosing PN63 seems not very suitable. Is the operating pressure of 3.5 Mpa and the design pressure of 5 Mpa due to factors such as the medium? All these aspects need to be taken into consideration.
On that 20592 standard, isn’t the operating temperature and the maximum allowable operating pressure (gauge pressure) specified in that table? Then why aren’t the design temperature and design pressure specified in those standards?
The maximum allowable operating pressure is different from the operational pressure. The maximum allowable operating pressure is less than or equal to the design pressure. It can be considered quite so