I. Classification of conveyed fluids by ANSI / ASME B31.3

         American National Standard ASME Pressure Piping Code ANSI / ASME B31.3 (hereinafter referred to as B31.3) according to the nature of the transported fluid and the consequences of leakage, the chemical plant and refinery pipeline transportation of fluids are divided into Class D, Class M and nature of the third category of fluids between the two.

    Class D fluids are non-flammable, non-toxic, and harmless to human muscle under operating conditions; design pressure does not exceed 150lbf/in2 (1.05MPa); and design temperature ranges from -20oF (-29oC) to 366oF (186oC) Class M fluids are highly toxic, and if a small amount leaks into the environment during transportation, inhalation or contact with the human body can result in serious and difficult-to-treat injuries, even if quick action is taken. If a small amount leaks into the environment during transportation, inhalation or contact with the human body can cause serious and untreatable injuries, which cannot be saved even if quick measures are taken. Fluid category can be determined according to ANSI / ASME B31.3 chapter specific requirements of the fluid piping design, construction and inspection.

Second, Sinopec's classification of pressure piping categories

     1 Sinopec on the "Pressure Piping Design Qualification Category Level Recognition and Installation Single Qualification Implementation Rules", the category of pressure piping is divided into the following table.

 Categories of Pressure Piping

    Notes:

    ①Conveyance distance means the direct distance between the origin, the repository, and the user of the pipeline used to convey the commodity medium.

    ②GB 5044as defined in the Classification of Hazards of Occupational Exposure to Poisons.

    ③GB 50160The Code of Practice for Fire Protection in the Design of Petrochemical Enterprises.

2 、SH 3059The grading of the pipeline is shown in the table below.

    SH 3059--2001General Rules for the Selection of Equipment for Petrochemical Piping Design, Piping Classification

Notes:

    ①The degree of toxicity is classified according to the Classification of Hazardous Degree of Occupational Exposure to Toxic Substances (GB 5044). Extremely hazardous belongs to Class I, the maximum permissible concentration of hazardous substances in the air of the workshop is ＜0.1mg/m3; highly hazardous belongs to Class II, the maximum permissible concentration is 0.1mg/m3. Extremely hazardous mediums are such as benzene, vinyl chloride, chloromethyl ether, cyanide, etc.; highly hazardous mediums are such as carbon disulphide, chlorine, acrylonitrile, hydrogen sulphide, formaldehyde, hydrogen fluoride, monohydrocarbon-based carbon and so on. See GB 5044 for details.

    ②Category A and B combustible gases are classified according to the fire hazard classification of combustible gases in the Code for the Design and Fire Protection of Petrochemical Enterprises (GB 50160). Category A refers to combustible gases and air mixture and the lower limit of explosion ＜10% (body); Category B is ≥10% (body). Class A combustible gases such as acetylene, ethylene oxide, hydrogen syngas, hydrogen sulfide, ethylene, propylene, methane, ethane, propane, butane and so on. See GB 50160 for details.

③The fire hazard classification of combustible gases, liquefied hydrocarbons, and combustible liquids is determined according to GB 50160, as shown in the table below.

    ④Mixtures should be graded on the basis of their dominant material.

    ⑤Class B liquids shall be regarded as Class A B liquids when the operating temperature exceeds their flash point, and Class C liquids shall be regarded as Class B A liquids when the operating temperature exceeds their flash point.