Two questions regarding the design of pressure pipelines

Classification of qualification categories and levels for pressure pipeline installation: GA category (long-distance pipelines). Long-distance (oil and gas) pipelines refer to those used for transporting commercial fluids between production sites, storage facilities, and end-users, and are divided into GA1 level and GA2 level. B1.1 GAl class: Long-distance pipelines that meet one of the following conditions are classified as GA1 class: (1) Long-distance pipelines that transport toxic, flammable, or explosive gas media and have a maximum operating pressure greater than 4.0 MPa ； (2) Long-distance pipelines that transport toxic, flammable, or explosive liquid media, with a maximum operating pressure of 6.4 MPa or higher, and a transmission distance (referring to the length of the pipelines used to transport such media between the source, storage location, and users) of 200 km or more. Long-distance (oil and gas) pipelines other than B1.2GA2 grade and GA1 grade are classified as GA2 grade. GB category (public pipelines): Public pipelines refer to gas and heat pipelines used for public services or domestic purposes within cities or towns, and are classified into GB1 level and GB2 level. B2.1GBl class urban gas pipelines. B2.2GB Level 2 Urban heating pipelines. GC class (industrial pipelines): Industrial pipelines refer to the process pipelines, utility pipelines, and other auxiliary pipelines owned by enterprises and institutions that are used for transporting process media. They are classified into GC1 grade, GC2 grade, and GC3 grade. B3.1 Class GCl: Industrial pipelines that meet one of the following conditions are classified as GC1 class: (1) Pipelines that transport media with an extreme hazard level of toxicity as specified in GB 5044—85 \"Classification of Hazards from Occupational Exposure to Toxic Substances\", highly hazardous gaseous media, and highly hazardous liquid media whose operating temperature is above their standard boiling point ； (2) Pipelines that transport flammable gases of Class A or B, or flammable liquids of Class A (including liquefied hydrocarbons), as specified in GB 50160‑1999 \"Code for Fire Protection Design of Petrochemical Enterprises\" and GB 50016‑2006 \"Code for Fire Protection Design of Buildings\", and whose design pressure is 4.0 MPa or higher ； (3) Piping for transporting fluid media with a design pressure of 10.0 MPa or more, or a design pressure of 4.0 MPa or more and a design temperature of 400°C or more. B3.2GC2 class: Pipes whose toxicity hazard level of the medium, fire hazard (flammability), design pressure, and design temperature are lower than those of GC3 class pipes specified in B3.3 of these regulations, except for the GC3 class pipes mentioned therein. B3.3GC3 class: Pipes for transporting non-toxic, non-flammable fluid media, with a design pressure of less than or equal to 1.0 MPa, and a design temperature greater than –20 °C but less than 185 °C. GD category (power pipelines) refers to the pipelines used in thermal power plants for transporting steam and two-phase steam-water mixtures, and is divided into GD1 grade and GD2 grade. B4.1GD1 grade: Pipes with a design pressure of 6.3 MPa or more, or a design temperature of 400°C or more. B4.2GD2 class: Pipes with a design pressure of less than 6.3 MPa and a design temperature of less than 400°C.

Reply to 2# kevin101134: Thank you for the reply from above

Reply to 3# gavinxkm: I searched on the forum just now; a comprehensive explanation of this issue can be found at http://bbs.hcbbs.com/viewthread.php?tid=293165