Regarding the temperature range issue in the calculation of pipeline flexibility

Thread Content

Hello, everyone in this forum. Regarding which pipes are required to undergo flexible analysis according to domestic standards, I have listed GB 20801, SH 3041, and GB 50316 as the relevant standards; there are slight differences in the specified temperature ranges. What are your thoughts on this? In practical design, by how much above the limit should temperature be before stress analysis is required? GB 20801.3-2006 Code for pressure pipelines – Industrial pipelines – Part 3: Design and calculation 7.1.1 Pipeline systems that meet one of the following conditions shall undergo pipeline stress analysis in accordance with the requirements of this chapter: a) The pipe connections to the equipment have special load requirements ； b) Piping with more than 7,000 thermal cycles over the expected service life ； c) Pipelines with an operating temperature of 400 ℃ or higher, or ≤ –70 ℃. 7.1.2 A piping system that meets one of the following conditions may be exempt from stress analysis: a) a piping system that is essentially the same or substantially equivalent to a well-functioning piping system ； b) Confirm that the pipeline system has sufficient strength and flexibility compared to those that have undergone stress analysis. SH-T 3041-2016 Code for Flexible Design of Petrochemical Piping 4.2 The following pipelines should be subjected to detailed flexible design using computer analysis methods: (1) Pipelines with operating temperatures greater than 400°C or less than -70°C ； (2) High-temperature pipes entering and exiting the heating furnace and steam generator ； (3) High-temperature pipes entering and leaving the reactor ； (4) Steam pipes entering and leaving the turbine ； (5) Process pipelines for entering and exiting centrifugal compressors and reciprocating compressors ； (6) The piping connected to the centrifugal pump can adopt a flexible design method as specified in the design requirements or as shown in Figure 4.2 ； (7) Pipelines with special stress requirements at the equipment connections ； (8) After applying the simplified analysis method, identify the pipelines that require further detailed analysis. 4.3 The following pipelines do not require flexible analysis: (1) Pipelines with the same or essentially equivalent flexibility as those in good operating condition ； (2) Compare with the analyzed pipes to confirm that the pipe has sufficient flexibility ； GB 50316-2008 Code for Design of Industrial Metal Piping: 9.2.1 The scope of flexible calculation shall comply with the following provisions: 9.2.1.1 When the design temperature of the pipeline is less than or equal to -50°C or greater than or equal to 100°C, it shall fall within the scope of flexible calculation. 9.2..1.2 The nominal diameter range for flexible computing shall be determined during the engineering design, based on the design temperature and the specific piping layout. 9.2.1.3 Piping that meets one of the following conditions, other than those specified in paragraph 9.2.1.1, shall be included in the flexible calculation: (1) long-distance piping without insulation that is affected by outdoor ambient temperatures ； (2) Pipelines with large additional displacement at the endpoints, for which flexibility cannot be determined empirically ； (3) When a small pipe is connected to a large pipe, and the movement of the large pipe affects the assessment of flexibility, the small pipe should be calculated simultaneously with the large pipe. 9.2.1.4 Piping that meets one of the following conditions may be exempt from flexible analysis: (1) The piping is identical to another piping system that is operating properly ； (2) Compared with the pipeline that has passed the flexibility analysis, there is almost no change in this pipeline.