Pipeline grading assistance requested
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Section 3.2.1 of 50235 states that industrial metal pressure pipelines are classified into GC1/GC2/GC3 in accordance with TSG D0001. Section 3.2.2 specifies that pipelines other than pressure pipelines should be classified as Category C fluid pipelines or Category D fluid pipelines. In terms of terminology, Class D fluid pipelines refer to those for fluids that are non-flammable and non-toxic, or have only a low level of toxicity, with a design pressure of 1.0 MPa or less, and a design temperature ranging from above -20°C to 185°C. Class C refers to fluid pipelines that are non-flammable and non-toxic, or have only a low level of toxicity, and do not fall under Class D. GC3 refers to pipe systems that use non-toxic, non-flammable fluid media, with a design pressure of 1.0 or less, and a design temperature ranging from above -20°C to 185°C. Why does it seem a bit contradictory? I hope everyone can help answer this
It can be understood in this way, but nitrogen at 0.5 MPAG and 40°C, with a DN80 diameter, does not fall under the category of pressure pipelines; according to the definition of pressure pipelines, such pipelines are those with a nominal diameter of 50 mm or more. Except for pipes with a nominal diameter of less than 150 mm and a maximum operating pressure of less than 1.6 MPa (gauge pressure), as well as the pipes that form part of the equipment used for transporting non-toxic, non-flammable, and non-corrosive gases.\" 2. In actual design work, pipelines that are not under pressure are also designed as if they were pressure pipelines. For example, a pipeline specified as “nitrogen, 0.5 MPAG, 40°C, DN80” is not considered a pressure pipeline; it is designed according to GC3 standards rather than being classified as Category D. 3. Generally speaking, only pipelines with a high risk level are classified as pressure pipelines and fall under supervision; they must be designed in accordance with relevant standards. Non-pressure pipelines that are not under supervision can also be designed rigorously following the specifications for pressure pipelines.