Pressure pipeline categories and grades

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I. Classification of fluids transported under ANSI/ASME B31.3 The American standard ASME Code for Pressure Vessels, ANSI/ASME B31.3 (hereinafter referred to as B31.3), classifies the fluids transported through pipelines in chemical plants and refineries into Category D, Category M, and a third category whose properties lie between those of the two preceding categories, based on the characteristics of the fluids being transported and the consequences of leaks. Class D fluids are non-flammable, non-toxic, and harmless to human tissue under operating conditions ； The design pressure shall not exceed 150 lbf/in2 (1.05 MPa) ； Assume the design temperature is between -20°F (-29°C) and 366°F (186°C). Class M fluids are highly toxic; even a small amount of them leaking into the environment during transportation, and being inhaled or coming into contact with the human body, can cause severe and difficult-to-treat injuries, and no measures taken quickly can prevent harm. Once the fluid category is determined, the piping for that fluid can be designed, constructed, and inspected in accordance with the relevant provisions of ANSI/ASME B31.3. II. Sinopec’s Classification of Pressure Pipelines 1. According to Sinopec’s Detailed Rules for the Recognition of Qualification Categories and Levels for Pressure Pipeline Design, as well as for the Qualifications of Installation Units, the classification of pressure pipelines is shown in the table below. Categories of pressure pipelines: Pipeline categories, characteristics of the transported medium, and design conditions
GA (long-distance pipelines): GA11 – Toxic, flammable, or explosive gases, with a design pressure of p > 1.6 MPa; 2 – Toxic, flammable, or explosive gases①, with a transmission distance of ≥ 200 km and a diameter of DN ≥ 300 mm; 3 – slurries, with a transmission distance of ≥ 50 km and a diameter of DN ≥ 150 mm.
GA21 – Toxic, flammable, or explosive gases, with a design pressure of p ≤ 1.6 MPa; 2 – Those outside the scope of GA1(2); 3 – Those outside the scope of GA1(3).
GB (utility pipelines): GB1 – Gas; GB2 – Thermal energy.
GC (industrial pipelines): GC11 – Media with an extremely high level of toxicity②; 2 – Flammable gases of categories A and B or liquids of category A③, with a design pressure of p ≥ 4.0 MPa; 3 – Flammable or toxic fluids with a design pressure of p ≥ 4.0 MPa and a design temperature of T ≥ 400°C; 4 – Fluids with a design pressure of p ≥ 10.0 MPa.
GC21 – Flammable gases of categories A and B or liquids of category A, with a design pressure of p < 4.0 MPa; 2 – Flammable or toxic fluids with p < 4.0 MPa and T ≥ 400°C; 3 – Non-flammable or toxic fluids with p < 10.0 MPa and T ≥ 400°C; 4 – Fluids with p < 10.0 MPa and T < 400°C.
Note: ① The transmission distance refers to the direct distance between the source, storage facility, and user, as measured along the pipeline used for transporting the medium. ②As specified in GB 5044 \"Classification of the Hazard Levels of Occupational Exposure to Toxic Substances\". ③As specified in GB 50160, the Code for Fire Protection Design of Petrochemical Enterprises. 2. The classification of pipes for SH 3059 is shown in the table below. SH 3059—2001 \"General Rules for the Selection of Materials for Petrochemical Piping\" – Piping classification; Applicable scope of piping grades: SHA1, for pipelines carrying media with an extremely hazardous toxicity level (except benzene pipelines) ； 2. Pipelines for acrylonitrile, phosgene, carbon disulfide, and hydrogen fluoride – media with a high degree of toxicity and considered highly hazardous substances ； 3. Medium pipelines with a design pressure of 10.0 MPa or higher, SHB1; benzene pipelines involving media with an extremely hazardous toxicity level ； 2. Pipelines carrying media with a high level of toxicity (except for acrylonitrile, phosgene, carbon disulfide, and hydrogen fluoride). 3. Pipelines carrying Class A and Class B flammable gases, as well as Class A1 liquefied hydrocarbons, and Class B and Class A2 flammable liquid media. SHC1: Pipelines carrying media with moderate or low levels of toxicity ； 2. Pipelines for flammable liquid media of Class B and Class C; low-temperature pipelines with a SHD design temperature below -29°C; pipelines for non-toxic, non-flammable media with a SHE design pressure less than 10.0 MPa and a design temperature equal to or greater than -29°C. Note: ① The degree of toxicity is classified in accordance with the \"Classification of Hazards from Occupational Exposure to Toxic Substances\" (GB 5044). Extreme hazard is classified as Level I; the maximum allowable concentration of harmful substances in workshop air is <0.1 mg/m3 ； High hazard is classified as Level II, with a maximum allowable concentration of 0.1 mg/m3. Highly hazardous substances such as benzene, vinyl chloride, chloromethane, cyanides, etc ； Highly hazardous substances such as carbon disulfide, chlorine, acrylonitrile, hydrogen sulfide, formaldehyde, hydrogen fluoride, methane, etc. See GB 5044 for details. ②Class A and Class B flammable gases are classified according to the fire hazard classification of flammable gases specified in the Code for Fire Protection Design of Petrochemical Enterprises (GB 50160). Class A refers to combustible gas-air mixtures with an explosion lower limit of <10% (by volume) ； Category B is ≥10% (by body weight). Class A flammable gases such as acetylene, ethylene oxide, hydrogen syngas, hydrogen sulfide, ethylene, propylene, methane, ethane, propane, butane, etc. See GB 50160 for details. ③The fire hazard classification for combustible gases, liquefied hydrocarbons, and combustible liquids is determined in accordance with GB 50160, as shown in the table below. Category Name, Characteristics, Examples:
A1 – Liquefied hydrocarbons: Hydrocarbon liquids and other similar liquids with a vapor pressure at 15°C greater than 0.1 MPa; examples include liquefied petroleum gas, liquefied natural gas, liquefied methane, liquefied propane, etc.
B – Flammable liquids: Liquids other than those in category A1, with a flash point less than 28°C; examples include gasoline, pentane, carbon disulfide, petroleum ether, crude oil, etc.
A2 – Flash point between 28°C and 45°C: Jet fuels, kerosene, cumene, styrene, etc.
B – Flash point between 45°C and 60°C: Light diesel fuel of grade -35, cyclopentane, etc.
A3 – Flash point between 60°C and 120°C: Light diesel fuel, heavy diesel fuel, heavy oil of grade 20, spindle oil, etc.
B – Flash point greater than 120°C: Wax oils, heavy oil of grade 100, oil residues, lubricating oils, transformer oils, etc.
A – Flammable gases: Gases whose explosive limit in mixtures with air is less than 10% (by volume).
B – Flammable gases: Gases whose explosive limit in mixtures with air is 10% or more (by volume).
④ The classification of a mixture should be based on its dominant component. ⑤Class B liquids whose operating temperature exceeds their flash point should be considered as Class A B liquids ； Class C liquids whose operating temperature exceeds their flash point should be considered Class B A liquids.