Study Questions on the Regulations for Safety Technical Inspection of Pressure Vessels

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This post was last edited by The wise are not confused on 2009-7-13 15:42. Chapter 1: Regulations and Standards 1-1: What are the main regulations and standards that must be followed in the design of pressure vessels? Answer: 1. State Council Document No. 22: Interim Regulations on the Safety Supervision of Boilers and Pressure Vessels (abbreviated as the “Regulations”) ； 2. Laborer’s Pot No. 6: Implementation Rules of the Interim Regulations on the Safety Supervision of Boilers and Pressure Vessels ； 3. Ministry of Labor Order No. 264: Notice on Amending the Relevant Provisions in the \"Pressure Vessels Section\" of the Implementing Rules for the Interim Regulations on the Safety Supervision of Boilers and Pressure Vessels ； 4. Quality and Technical Supervision Bureau Document No. 154: “Regulations on the Safety Technical Inspection of Pressure Vessels” (abbreviated as “Vessel Regulations”) ； 5. Ministry of Labor Order No. 370: “Regulations on the Safety Inspection of Ultra-High Pressure Vessels” ； 6. Ministry of Labor Order No. 51: Rules for the Management and Supervision of the Qualifications of Pressure Vessel Design Organizations ； 7. Ministry of Labor Order No. 145: Provisions regarding design firms for pressure vessels regarding the implementation of the \"Steel Pressure Vessels – Analysis and Design Standards\" ； 8. Ministry of Labor Order No. 262: Regulations on Safety Supervision of Liquefied Gas Road Tankers ； 9. Transformed Character No. 1174: “Regulations on the Safety Management of Railway Tank Cars for Liquefied Gases” ； 10. Quality and Technical Supervision Bureau Document No. 218: “Regulations on the Safety Management of Medical Oxygen Chambers”. 1-2 What are the responsibilities of the pressure vessel design unit? Answer: 1. The design unit shall be responsible for the accuracy and completeness of the design documents ； 2. The design documents for the container shall include at least a design calculation sheet and design drawings ； 3. The general layout drawing of the container design shall bear the approval mark from the pressure vessel design unit. 1- What is the scope of application and non-application of GB150-1998 \"Steel Pressure Vessels\"? 3 Answer: Scope of application: 1. Steel containers with a design pressure not exceeding 35 MPa ； 2. The design temperature range is determined based on the allowable operating temperature of the steel. Areas where it is not applicable: 1. Containers heated directly by flame ； 2. Vessels in nuclear power installations ； 3. Pressure chambers that are integral to or serve as components in mechanical devices with rotational or reciprocating motion (such as pumps, compressors, turbines, hydraulic cylinders, etc.) ； 4. Containers that are frequently moved ； 5. Vessels with a design pressure of less than 0.1 MPa ； 6. Containers with a vacuum level below 0.02 MPa ； 7. Containers with an inner diameter (for non-circular cross-sections, referring to width, height, or diagonal; for example, the diagonal for rectangles and the major axis for ellipses) of less than 150 mm ； 8. Containers requiring labor analysis to be invalidated ； 9. There are already containers that comply with standards from other industries, such as certain specialized containers and glass-lined containers used in industries like refrigeration, sugar production, papermaking, and beverages. 1-4 What are the scope of application and non-application of the «Regulations on Safety Inspection of Pressure Vessels»? Answer: It applies to pressure vessels that meet all of the following 3 conditions (except those specified in Article 2, Paragraph 2): 1. The maximum operating pressure (pW) is greater than or equal to 0.1 MPa (excluding hydrostatic pressure) ； 2. The inner diameter (for non-circular cross-sections, this refers to the maximum dimension) is greater than or equal to 0.15 m, and the volume (V) is greater than or equal to 0.025 m3 ； 3. The medium contained is a gas, a liquefied gas, or a liquid whose maximum operating temperature is equal to or higher than its standard boiling point. Not applicable to the following pressure vessels: 1. Ultra-high pressure vessels ； 2. Various types of gas cylinders ； 3. Pressure vessels manufactured from non-metallic materials ； 4. Nuclear pressure vessels, auxiliary pressure vessels on ships and railway locomotives, pressure vessels for defense or **equipment, pressure vessels operating under vacuum (excluding jacketed pressure vessels), and devices directly heated by flames falling within the scope of various boiler safety inspection regulations (such as flue-type waste heat boilers, etc.) ； 5. Pressure vessels whose maximum operating pressure under normal conditions is less than 0.1 Mpa (including those that need to withstand a pressure of 0.1 MPa or more momentarily during feeding or discharging processes, but excluding those that require short-term exposure to a pressure of 0.1 MPa or more during processes such as disinfection or cooling) ； 6. Non-independent pressure-bearing components on the machine (including compressors, generators, pumps, diesel engine cylinders or pressure-bearing housings, etc., excluding drying drums in paper and textile machinery and auxiliary pressure vessels for compressors) ； 7. Shellless coil exchangers, corrugated plate exchangers, air-cooled exchangers, cooling tubes. 1-5 How do the \"Code for Pressure Vessels\" and GB150-1998 define the scope of pressure vessels? Answer: In addition to the pressure vessel itself, it should also include: 1. The welding groove of the first circumferential weld where the pressure vessel is welded to external pipes or devices, the first threaded joint in case of threaded connections, the first flange sealing surface in case of flanged connections, and the first sealing surface in case of special connections or fittings ； 2. Pressure cover for the opening part of the pressure vessel and its fasteners ； 3. Welded joints connecting non-compressed components to the pressure vessel body. 1-6 What is the explosion limit? Answer: When the vapor of flammable gases or liquids, or flammable dusts, mixes with air to reach a certain concentration, an explosion occurs upon encountering a source of fire. The concentration range of an air mixture at which explosion occurs is known as the explosive limit. The explosion limit is usually expressed as the volume percentage of combustible gas, vapor, or dust in air. The lowest concentration is called the \"lower explosive limit\", while the highest concentration is called the \"upper explosive limit\". No explosion occurs when the concentration is below the lower explosive limit or above the upper explosive limit. 1-7 What are the ignition point and flash point? Answer: The ignition point refers to the heat of combustion released when a combustible substance is heated and ignited; this heat is sufficient to cause the substance to emit enough combustible vapor to sustain the continuation of combustion. The lowest temperature required to heat this substance at this point is known as its \"ignition point,\" or also referred to as the burning point. The lower the ignition point of a substance, the easier it is to burn. The flash point is the lowest temperature at which the vapor emitted by a flammable liquid, when mixed with air, can catch fire upon exposure to an ignition source. The flash point is different from the ignition point; the flash point is slightly lower than the ignition point. 1-8 How are flammable and combustible liquids classified? Answer: Generally, they are classified into four grades and two categories: Grade 1 has a flash point of 45°C to ≤120°C; Grade 4 has a flash point >120°C. Liquids in Grades 1 and 2 are referred to as flammable liquids ； Liquids of grades 3 and 4 are referred to as flammable liquids. 1-9 What are chemical hazardous substances? Answer: Any substance that possesses various degrees of hazardous properties such as flammability, explosiveness, toxicity, corrosivity, or radioactivity, and which can cause combustion, explosion, poisoning, burns, or other forms of harm to human health or damage to property as a result of external factors such as friction, impact, vibration, exposure to fire, sunlight, moisture, temperature changes, or contact with other substances that are incompatible with it, is considered a chemical hazard. 1-10 What is a flammable medium? Answer: Flammable media refer to gases whose lower explosive limit when mixed with air is <10% or whose difference between the upper and lower explosive limits is ≥20%, as well as liquids with a flash point ≤45%. 1-11 How is the toxicity level of the medium in pressure vessels and flammable media classified? Answer: (1) The classification of the toxicity level of chemical media and the flammability of such media in pressure vessels is based on the provisions of HG20660 \"Classification of Toxicity Hazards and Explosion Risks of Chemical Media in Pressure Vessels\". When no specific provisions are given, the degree of toxicity is determined according to the following principles: 1. Extremely hazardous (Grade I): The maximum allowable concentration is <0.1 mg/m3 ； 2. Highly hazardous (Class II): Maximum allowable concentration of 0.1–<1.0 mg/m3 ； 3. Moderate hazard (Grade III): Maximum allowable concentration of 1.0–<10 mg/m3 ； 4. Mild hazard (Grade IV): The maximum allowable concentration is ≥10 mg/m3. (II) When the medium in a pressure vessel is a mixture, the toxicity level of the medium or information indicating whether it is a flammable medium shall be provided by the process design team of the design unit, or by the production technology department of the operating unit, based on the components of the medium and in accordance with the aforementioned criteria for toxicity or flammability. If such information cannot be provided, the determination shall be made based on the medium with the highest level of toxic hazard or explosion risk. 1-12 How are the pressure grades of pressure vessels classified? Answer: Pressure vessels are classified into four pressure grades according to their design pressure (p): low pressure, medium pressure, high pressure, and ultra-high pressure. The specific classifications are as follows: 1. Low pressure (code L): 0.1MPa ≤ p < 1.6MPa; 2. Medium pressure (code M): 1.6MPa ≤ p < 10MPa; 3. High pressure (code H): 10MPa ≤ p < 100MPa; 4. Ultra-high pressure (code U): p ≥ 100MPa. What are the main types of pressure vessels? Answer: Based on the principle of function in the production process, pressure vessels are classified into reaction pressure vessels, heat exchange pressure vessels, separation pressure vessels, and storage pressure vessels. The specific classifications are as follows: (1) Reaction pressure vessels (code R): These are pressure vessels primarily used to carry out physical and chemical reactions of substances, such as reactors, reaction kettles, decomposition pots, sulfidation tanks, decomposition towers, polymerization kettles, high-pressure reactors, ultra-high-pressure reactors, synthesis towers, shift reactors, cooking pots, steam generators, autoclaves, and gas generators ； (II) Heat exchange pressure vessels (code E): These are pressure vessels primarily used for facilitating heat exchange of fluids, such as shell-and-tube waste heat boilers, heat exchangers, coolers, condensers, evaporators, heaters, sterilization kettles, dyeing machines, drying cylinders, steaming and frying pots, preheating kettles, solvent preheaters, steam generators, and gas generator water jackets ； (III) Separation pressure vessels (code S): These are pressure vessels primarily used for achieving fluid pressure balance and buffering, as well as for the purification and separation of gases; examples include separators, filters, oil collectors, buffers, washers, absorption towers, copper washing towers, drying towers, stripping towers, steam separators, and deaerators ； (IV) Storage pressure vessels (code C, with spherical tanks coded as B): These are pressure vessels primarily used for storing gases, liquids, liquefied gases, and other such substances, such as storage tanks of various types. 1-14 How does the Code define volume? How is the volume of the shell side and tube side in a shell-and-tube heat exchanger, as well as the jacket inside a jacketed vessel, calculated? Answer: Volume refers to the geometric volume of a pressure vessel, that is, the volume calculated from the dimensions specified in the design drawings (without considering manufacturing tolerances) and rounded off, without deducting the volume of the internal components. For shell-and-tube heat exchangers, the shell side volume is the geometric volume of the shell side excluding the volume of internal components such as the heat exchange tubes, while the tube side volume is the sum of the geometric volume of the tube box and the volume inside the heat exchange tubes. For a jacketed vessel, the volume inside the jacket is the geometric volume of the jacket minus the volume occupied by the inner vessel. 1-15 What is the purpose of the Code on Pressure Vessels in classifying pressure vessels into three categories? What is the principle behind its classification? Answer: To facilitate safety technology supervision and management, pressure vessels within the scope of application of the Relevant Regulations are classified into three categories. The principles for this classification are as follows: 1. Pressure vessels falling under any of the following circumstances are classified as Category 3 pressure vessels: (1) High-pressure vessels ； (2) Medium-pressure vessels (only for media with extremely high and high toxicity) ； (3) Medium-pressure storage vessels (only for flammable or moderately hazardous media with a pV product of 10 MPa•m3 or greater) ； (4) Medium-pressure reaction vessel (only for flammable or moderately hazardous media with a pV product of 0.5 MPa•m3 or greater) ； (5) Low-pressure vessels (only for media with extremely high or high toxicity, and a pV product of 0.2 MPa•m3 or greater) ； (6) High-pressure and medium-pressure shell-and-tube waste heat boilers ； (7) Medium-pressure glass-lined pressure vessels ； (8) Pressure vessels manufactured from materials with a high strength level (meaning that the minimum specified value for tensile strength in the relevant standards is 540 Mpa or higher) ； (9) Mobile pressure vessels, including railway tank cars (for liquefied gases and cryogenic liquids), tank trucks, and tank containers (for liquefied gases and cryogenic liquids), etc ； (10) Spherical storage tanks (volume greater than or equal to 50 m3) ； (11) Low-temperature liquid storage containers (volume greater than 5 m3). 2. A pressure vessel falls under Category II in any of the following situations (except as specified in Paragraph 1 of this article): (1) Medium-pressure vessels ； (2) Low-pressure vessels (only for media with extremely high and high toxicity) ； (3) Low-pressure reaction vessels and low-pressure storage vessels (only for flammable media or media with moderate toxicity) ； (4) Low-pressure shell-and-tube waste heat boiler ； (5) Low-pressure glass-lined pressure vessels. 3. Low-pressure vessels are classified as Class 1 pressure vessels (except as provided in paragraphs 1 and 2 of this article). 1-16 How are multi-chamber pressure vessels classified? Answer: For multi-chamber pressure vessels (such as the tube side and shell side of heat exchangers, the drum and heat exchange chamber of waste heat boilers, jacketed vessels, etc.), the category of the pressure chamber with the highest pressure determines the category of the entire multi-chamber vessel; however, design and manufacturing technical requirements shall be specified separately for each pressure chamber based on its own category. When classifying each chamber, its category should be determined based on the design pressure, properties of the medium, geometric volume, material, and type of that specific chamber; it is not permissible to combine the parameters of two or more chambers in order to assign a category. For example: there is a container with a jacket, the operating pressure inside the container is less than 0.1 MPa, and the toxicity level of the medium is highly hazardous ； The jacket contains low-pressure saturated steam at 120°C; therefore, this vessel should be classified as a Class 1 pressure vessel, rather than a Class 2 or Class 3 pressure vessel. 1-17 What is the relationship between the Compliance Regulations and the Ordinances and standards? Answer: The Interim Regulations on the Safety Supervision of Boilers and Pressure Vessels issued by the State Council (hereinafter referred to as the \"Regulations\") are administrative regulations. They constitute the basic legal framework for the safety supervision of boilers and pressure vessels in China, serving as the basis and guidelines for such supervision work. The \"Regulations on Safety Supervision of Pressure Vessels\" formulated in accordance with the \"Regulations\" (hereinafter referred to as the \"Vessel Regulations\") are also administrative regulations, establishing the most basic requirements for the safety supervision of pressure vessels from a safety perspective. **Standards and industry standards fall within the scope of civil litigation, and they serve as the basis for designing and manufacturing pressure vessel products. The Code for Pressure Vessels serves as the basis for the technical supervision and management of pressure vessel safety. Since the scope of safety technology supervision differs from those of standards in terms of tasks, nature, work progress, and perspective, some aspects may be consistent with standards while others may not; this is normal and does not represent a contradiction. There is no distinction between the two; as the entity responsible for the design and manufacturing of a product, it is necessary to comply with both the tolerance specifications and the relevant standards. When there is a discrepancy between them, it is advisable to follow the more stringent requirements. However, as the safety supervision agency for pressure vessels, it is sufficient as long as the products meet the requirements of the Pressure Vessel Regulations.