CO2 injection pipeline

If DN is not less than 50, it belongs to a pressure pipeline

According to this, it cannot be found even in the training materials for pressure pipelines

Should it be GA2 or GC1? It depends on which formula for wall thickness calculation should be used: the design specifications for gas pipelines, those for oil pipelines, or the specifications for oil and gas gathering systems? Or should the wall thickness be calculated according to the design specifications for industrial metal pipelines?

Pressure pipelines refer to tubular devices that use a certain pressure to transport gases or liquids. They are defined as pipelines with a maximum operating pressure of 0.1 MPa (gauge pressure) or more, carrying gases, liquefied gases, steam, or liquids that are flammable, explosive, toxic, corrosive, and have a maximum operating temperature equal to or higher than their standard boiling point, and with a nominal diameter of 50 mm or more.

To determine the pipeline category, first consider its purpose: does it belong to long-distance pipelines GA, utility pipelines GB, industrial pipelines GC, or power pipelines GD? Then further classify into levels. What kind of pipe is it?

There are no regulations or standards regarding injection pipelines. For high-pressure water injection pipelines, however, there are standards in place that classify them as non-pressure pipelines

GC14.1 Industrial pressure pipelines that meet one of the following conditions are classified as GC1 grade: 4.1.1 Pipelines transporting media with toxicity levels as specified in GB5044 and HG20660, namely: a) Highly hazardous media (except benzene)； b) Highly hazardous gas media (including benzene) ； c) Highly hazardous liquid media with a working temperature above the standard boiling point. 4.1.2 Pipelines that transport flammable gases of categories A and B as specified in GB50160 and GBJ16, with a design pressure of 4.0 MPa or higher: a) Flammable gases of categories A and B ； b) Class A flammable liquids (including liquefied hydrocarbons). 4.1.3 Pipelines that transport fluid media with a design pressure of 10.0 MPa or higher, as well as pipelines with a design pressure of 4.0 MPa or higher and a design temperature of 400°C or higher. 4.2 Industrial pressure pipelines that meet the following conditions are classified as GC2 grade: pipelines other than those of GC3 grade specified in clause 4.3, whose toxicity hazard level of the medium, fire hazard (flammability), design pressure, and design temperature are lower than those specified in clause 4.1 (GC1 grade). 4.3 Industrial pressure pipelines that meet the following conditions are classified as GC3 grade: pipelines that transport non-toxic, non-flammable fluid media, with a design pressure of less than or equal to 1.0 MPa and a design temperature higher than -20°C but not higher than +186°C. 4.4 When dealing with mixed media with different toxicity or flammability levels, consideration should be given to the medium with the highest level of toxicity or flammability hazard. When the concentration of a hazardous substance is extremely low, a comprehensive consideration of its degree of hazard and concentration is required, and it is up to the owner or designer to determine the toxicity or flammability category of the mixed substance.

Well, according to GC1 4.1.3, the formula for calculating the wall thickness of high-pressure water injection pipes (classified as non-metallic pipes) is basically the same as that used for industrial metal pipes. Thank you all for your discussions and contributions