How to understand the most demanding combination of operating pressure and temperature for pipelines
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I would like to ask fellow sailors: The design pressure of a pipeline refers to the pressure under the most severe conditions among all possible combinations of operating pressure and temperature that the piping system may encounter during operation. In this statement, how should the pressure under the most severe conditions in the combination of working pressure and working temperature be understood? For example, Combination 1 is 2.0 MPa at 750°C, and Combination 2 is 5.0 MPa at 50°C; how should the design pressure of the pipeline be determined?
The design pressure is the maximum allowable operating pressure for pipeline design; it takes into account not only the highest operating pressure that the pipeline may experience but also the effect of operating temperature on the pipeline. During the design process, the strength and stability at different temperatures are evaluated, and the most stringent conditions are selected to determine the design pressure. Among combination 1 and combination 2 that you mentioned, it is clear that combination 1 operates at a higher temperature; therefore, the design pressure should be determined based on combination 1. The specific design pressure needs to be calculated based on actual conditions and design standards. .
Thank you for your guidance. Is this calculation process described or illustrated in any standards or reference books? I’d like to understand it in more depth. Thank you.
The calculation process for design pressure generally follows **or industry standards, such as China’s \"Code for Design of Steel Pressure Piping\" (GB 50235-2001), as well as ASME B31.1 and B31.3 in the United States. These standards or specifications generally provide calculation formulas, methods for calculation, and the range of values for various parameters, which can be selected and applied according to specific circumstances. At the same time, relevant textbooks and manuals can also be referred to, such as the \"Industrial Pipeline Design Manual\" and the \"Piping Engineering Manual\", etc. If in-depth understanding and application are required, it is recommended to consult a professional pipeline designer or relevant engineer. .
The most severe conditions in the combination of operating pressure and operating temperature refer to the most unfavorable situations that a piping system may encounter during actual use. In other words, the design of the piping system should take into account the highest possible combination of operating pressure and operating temperature to ensure its sufficient strength and stability. For the two given combinations, the design pressure should be determined based on 2.0 MPa and 750°C in Combination 1. Because at the same diameter, a higher pressure is exerted under high temperatures, the piping system needs to have greater strength and an appropriate safety margin.
Design pressure: 5 MPa; Design temperature: 750 degrees
The specifications clearly state that the maximum pressure and maximum temperature should not be simply combined as design conditions
Hello, may I ask which standard it is? I would like to learn about it*
I know. This is the current situation with valves in China: it’s not required that all conditions be met simultaneously. It’s impossible to set the design parameters at 2 MPa and 750 degrees; if the actual operating pressure reaches 5 MPa, it will definitely be considered overpressure. Alternatively, the design parameters can be set at 5 MPa and 200 degrees, but if the actual temperature reaches 750 degrees, that too is considered overheating
According to GB20801, the so-called most severe operating conditions refer to those that result in the greatest wall thickness and the highest pressure rating for pipeline components. There are formulas for determining the wall thickness of pipelines, while flanges and valves have specified temperature and pressure ratings. By calculating the wall thickness under these two types of conditions and selecting the appropriate pressure rating for the pipeline components, it is possible to determine the most severe operating conditions
How many years has my brother been retired now? He even brings out those old-fashioned rules