Regarding the determination of design parameters and test pressure of pipelines?
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Hello experts. A new pipe is installed on site, pipe number: 100-AW-11704-26CP1, the design conditions provided by the single-line diagram of this pipeline in the design data are 100℃/14.3MPa, and the water pressure is 21.45MPa. However, if the pipeline grade is 26CP1, check the "Pipeline Grade Table" in the design data. The design conditions are 16.0MPa/100℃. According to the standard calculation, the water pressure should be 24MPa. Which one should be used? Thanks
Perform according to the design pressure and test pressure of the pipeline. The pressure in the pipeline grade table and the pipeline design pressure are similar to the relationship between the pressure grade of the flange and the pipeline design pressure.
Refer to Figure 1. Figure 2 only represents the pipeline grade, which is just a value to distinguish which pressure level the pipeline belongs to.
Both the pipe grade table and the single line diagram are acceptable. The pipeline grade table is recalculated by the pipeline professional based on process parameters (parameters of the single-line icon) combined with standards. From an economic perspective, the parameters of the single-line icon are best suppressed, with low pressure and parameters that meet the process operation requirements. However, the purpose of suppression is not achieved. During transportation and installation, the pipe is sometimes deformed. Suppression according to the pipeline grade table is to make the pipe evenly stressed and more circular, but the parameters of the single-line icon cannot be guaranteed. Most of the domestic ones follow the parameters of the single-line icon, which mainly saves money and is relatively safe secondly.
The pressure on the pipeline grade table is only the nominal pressure of the pipeline, not the design pressure. Just follow the design pressure.
The design conditions should be the ones in the ISO diagram. For more accuracy, you should check the archived pipeline list of the craft professional, which is the most accurate. The ISO diagram is copied from the process professional piping table. Take a look at the pipeline professional's instructions. It should say that the archived pipeline table of the process professional shall prevail.