Basic knowledge of chemical equipment for operators

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1. The five key steps for equipment inspection are: listen, touch, check, observe, and smell. 2. In equipment management, the requirement is to understand four aspects and master three skills: understand the principles, understand the structure, understand the performance, and understand the manufacturing process； Know how to operate, maintain, and troubleshoot. 3. The five main types of valves used in chemical pipelines are: gate valves, globe valves, ball valves, check valves, and butterfly valves. Other common valves include: plug valves, safety valves, steam traps, diaphragm valves, lined valves, pressure relief valves, damping valves, etc. 4. Basic structure of pressure vessels: cylinder, head, flange, support, pipe connection, manhole, level gauge, sight glass, etc. Common types include horizontal storage and transportation pressure vessels, and vertical pressure vessels (towers). 5. Chemical industry pipe fittings include: elbows, tees, reducers, union joints, flange covers, blind plates, reduced tees, pipe caps, etc. 6. Common elbow types include: 90°, 45°, 60°, 180°. The elbow radius is in a multiple relationship, generally being 1 or 1.5 times the nominal diameter DN. 7. The materials used to make gaskets include special cardboard, rubber sheets, asbestos sheets, soft metal sheets, low-carbon steel, polytetrafluoroethylene, expanded graphite, and sealant fluids, among others. 8. The dynamic balance accuracy grade for the impellers of ordinary pumps, the rotors of standard motors, and the impellers of fans is: G6.3. 9. The safety accessories for pressure-bearing special equipment include: safety valves, rupture discs, level gauges, thermometers, and data acquisition and processing devices. 10. What are the categories of regular inspections for pressure vessels? How is its inspection cycle specified? There are three types: 1) External inspection, once a year ； 2) Internal inspection: at least once every 6 years for facilities with a safety status level of 1 or 2, and at least once every 3 years for those with a safety status level of 3 ； 3) Dielectric strength test: For fixed containers, it shall be conducted at least once every 2 internal and external inspections ； For mobile units, at least once every six years. 11. Before installing special equipment, which department should be notified in writing? The departments in charge of the safety supervision and management of special equipment in municipalities directly under the Central Government or cities with districts: 12. Serious violations related to special equipment include: 1) Designing special equipment without a license ； 2) Use of special equipment without a license ； 3) Unlicensed installation, modification, and repair of special equipment ； 4) Operating special equipment without a license ； 5) No periodic inspection for special equipment. 13. The safety valve of a boiler in use shall be calibrated at least once a year. 14. Names and codes for pipe flange sealing surfaces: In accordance with national standards, the names and codes for flange sealing surfaces are as follows: Flat surface: FF ； Convex surface: RF ； Rough and smooth surfaces: MF ； Mortise and tenon surface: TG ； Ring connection surface: RJ15; types of steel include steel plates, steel pipes, section steel, etc. Steel plates: Steel plates are divided into three categories: thin steel plates, medium-thickness steel plates, and thick steel plates. Steel pipes: Steel pipes are classified into three types: welded steel pipes, seamless steel pipes, and spiral pipes. 16. What are the types of steel profiles? Examples include round steel, square steel, hexagonal steel, flat steel, angle steel (equal-leg and unequal-leg), channel steel, I-beam, H-beam, etc. 17. What is the relationship between absolute pressure, gauge pressure, vacuum degree, and atmospheric pressure? Absolute pressure = Gauge pressure + Atmospheric pressure ； Vacuum degree = atmospheric pressure - absolute pressure. 18. 1 MPa = (10³) KPa = (10⁶) Pa. 19. The nominal diameter of a φ108×4 steel pipe is generally 100 mm, with a thickness of 4 mm. 20. The main performance parameters of centrifugal pumps include: flow rate, head, speed, efficiency, etc. 21. The performance indicators of lubricating oil include: viscosity, flash point, freezing point, acid value, mechanical impurities, ash content, lubricity, extreme pressure capacity, water content, etc. 22. Common methods for denoting steel grades: Q235BF – where Q represents the yield strength of the steel; it is the first letter of the pinyin character for “yield”. 235 denotes the yield strength in MPa. B indicates the quality grade, with common grades being A, B, C, D. F stands for boiling steel (b for semi-killed steel, z for killed steel, tz for specially killed steel). 23. Gray cast iron: HT150 – where HT is the code for gray cast iron ； 150—Tensile strength 24; the first characters of the valve model indicate the type of valve: Z J L Q D G X H A Y SZ—Globe valve ； J—Stop valve ； L—Throttle valve ； Q—Ball valve ； D—Butterfly valve ； G—Diaphragm valve ； X — Ball valve ； A—Safety valve ； S—Steam trap ； Y—Pressure relief valve ； H—Check valve/foot valve 25. The Arabic numerals following the initial letter of the valve model indicate the connection type: 1, 2, 4, 6, 7, 8, 9. 1—Internal thread ； 2—External thread ； 4—Flange ； 6—Welding ； 7—Wafer type ； 8—Clamp ； 9—What do the codes for the material of the ferrule 26, the valve stem, and the sealing surfaces or linings of the valve seat represent respectively? T X N H B H D Y Q C J PT—Copper alloy ； X—Rubber ； N—Nylon plastic ； H—Alloy steel ； B—Babbitt metal ； D—Nitriding steel ； Y—Hard steel ； Q—Lead lining ； C—Enamel ； J—rubber-lined ； P—Boronized steel 27. Write down what each alphanumeric character in the following valves represents? Q21H-40P-25: Ball valve, manual external thread type, with a valve core made of alloy steel; the valve body is made of 1Cr18Ni9Ti. The operating pressure is 4.0 Mpa, and the nominal diameter is 25. J41H-25P-100: Gate valve, flanged connection, manual operation; the valve core is made of alloy steel, and the valve body is also made of 1Cr18Ni9Ti. The operating pressure is 2.5 Mpa, and the nominal diameter is 100. J41B-25-50: Globe valve, flanged connection; the valve trim is made of tin-based bearing alloy. The working pressure is 2.5 Mpa, and the nominal diameter is 50. G41CJ-6-100: Diaphragm valve, flanged connection; the valve trim is made of carbon steel lined with rubber. The pressure rating is 0.6 Mpa, and the nominal diameter is 100. Z744W-2.5-600: Gate valve, hydraulically operated, flanged connection, double gate; the sealing material is directly machined onto the valve body. The working pressure is 0.25 Mpa, and the nominal diameter is 600. D341X-10-300: Butterfly valve, worm gear operated, flanged connection, single gate; the valve seat seal is made of rubber. The working pressure is 1.0 Mpa, and the nominal diameter is 300. 28. Types of sealing surfaces: Convex surface, concave surface, convex rabbeted surface, grooved surface, flat surface, ring joint surface. Codes: RFFMMTGFFRJ.
29. There are two main systems for flange standards: the European pipe flange system and the American flange system. The European pipe flange system (DIN, GB, JB, HG20592): Nominal pressures: 0.1, 0.25, 0.6, 1.0, 1.6, 2.5, 4.0, 6.4, 10.0, 16.0, 25.0, 32.0, 40.0 MPa ； Nominal diameter: 15~600mm ； Flange structural types: flat weld plate type, flat weld ring loose sleeve type, flanged loose sleeve type, butt weld flanged loose sleeve type, butt weld ring loose sleeve type, butt weld type, necked threaded connection type, integral type, and flange cover ； Flange sealing surfaces include: flat surface, concave surface, ribbed surface, tenon-and-socket surface, rubber ring connection surface, lens surface, and diaphragm welding surface ； American flange system: American ANSI B16.5 \"Steel Pipe Flanges and Flanged Fittings\" (including ANSI, GB, HG20615) ； Nominal pressure: 150psi (2.0Mpa), 300psi (5.0Mpa), 400psi (6.8Mpa), 600psi (10.0Mpa), 900psi (15.0Mpa), 1500psi (25.0Mpa), 2500psi (42.0Mpa) ； Nominal diameter: 6~4000mm ； Flange structural types: strip welding, socket welding, threaded connection, loose sleeve, butt welding, and flange cover ； Flange sealing surfaces: concave surface, concavo-convex surface, tenon-and-socket surface, metal ring connection surface. 30. The **standard system for steel pipe flanges in our country is based on GB standards. Nominal pressure: 0.25 Mpa to 42.0 Mpa. Series 1: PN1.0, PN1.6, PN2.0, PN5.0, PN10.0, PN15.0, PN25.0, PN42 (main series) ； Series 2: PN0.25, PN0.6, PN2.5, PN4.0. Among these, the flange sizes of the 6 grades PN0.25, PN0.6, PN1.0, PN1.6, PN2.5, and PN4.0 belong to the European flange system represented by German flanges, while the others belong to the American flange system represented by American flanges. In GB standards, the highest nominal pressure class for those belonging to the European flange system is 4 Mpa, while for those belonging to the American flange system, the highest nominal pressure class is 42 Mpa. 2) Nominal diameter: 10mm~4000mm. 31) Types of flange structures: ① Integral flanges: threaded flanges, welded flanges, butt-welded flanges, necked slip-on flanges, necked socket-welded flanges, plate-type slip-on flanges ； Flange cover (blind hole flange) ； ② Unit flanges: loose-flange type, welded-ring loose-flange with neck type, welded-ring loose-plate flange, butt-welded-ring loose-plate flange, plate-type flipped loose-flange ； 32. Flange sealing surfaces: flat, concave, convex-concave, tenon-and-socket, and ring-connected surfaces. 33. Common materials for bolts: For ordinary pipelines such as those for water or compressed air, which are not critical, 35A# carbon steel bolts are generally used ； Pipelines for flammable, explosive, and toxic media are mostly made of 35CrMoA/30CrMo material ； Usage of flange bolts for high-temperature pipelines: 510°C ----- 21CrMoV; 550°C ----- 20CrMoV, 21CrMoV; 570°C ----- 20CrMoVTiB, 20CrMoVnBTiB; 600°C ----- 2Cr12WMoVNbB; 650°C ----- GH213, 234. What is the general pattern regarding the relationship between size and length when obtaining pipeline flange connection bolts from the warehouse? What size ring wrench is used for M16 bolts? For example, in the case of M16: when the pressure rating is PN≤2.5 MPa, the length is 5 times the diameter; thus, M16X80 is used ； When the pressure rating PN is greater than 2.5 MPa, the length is 5 times the diameter plus 10; in this case, M16x90 should be used. For example, in the case of M20: when the pressure rating is PN≤2.5 MPa, the length is 5 times the diameter; thus, M20X100 is used ； When the pressure rating PN is greater than 2.5 MPa, the length is 5 times the diameter plus 10; in this case, M20x110 should be used. Note: [This does not apply to pressure levels of 6.0 MPa or higher; however, this value can be used as a reference.] For bolts of a certain specification, corresponding socket wrenches should be used. Generally, for bolts with a nominal size of X1.5, such as M16 bolts, the socket wrench size is 16*1.5=24 ； For M20 bolts, a ring wrench of size 20*1.5=30 is used. When using a slip joint wrench, try to select the size that is closest to the required measurement. 35. What are the common gaskets? Non-metallic gaskets: such as asbestos gaskets, synthetic resin gaskets, rubber gaskets, asbestos-free rubber gaskets, flexible graphite metal composite gaskets, and polytetrafluoroethylene gaskets. Semi-metallic gaskets: such as wound gaskets, wave-shaped gaskets, metal-wound gaskets, metal-toothed composite gaskets, and metal-clad gaskets. Metal gasket. For example: copper, aluminum, iron, steel, metal flat washers. 36. What are the common types of metal wound gaskets? There are four types of common metal wound gaskets: the basic type ； With inner and outer ring gaskets ； With inner ring ； With an outer ring. 37. For the D1222 model of wound gaskets, what do the digits in various positions of the model number represent? Such as the D1222 model of wound gaskets: D: Wound gasket with inner and outer reinforcement rings. First digit: Material of the outer ring: 1 – Low-carbon steel (20#). Second digit: Embedded material of the main body: 2 – 0Cr18Ni9 (304). Third digit: Outer covering material of the main body: 2 – Flexible graphite strip. Fourth digit: Material of the inner ring: 2 – 0Cr18Ni9 (304). Detailed explanation: First digit: Material of the outer ring; 0: No outer ring ； 1: Low-carbon steel (20#) ； 2: 0Cr18Ni9 (304) ； 3: 0Cr17Ni12Mo2 (316) ； 4: 0Cr17Ni14Mo2 (316L); the second digit indicates the embedded material of the main material. 2: 0Cr18Ni9 (304) ； 3: 0Cr17Ni12Mo2 (316) ； 4: 00Cr17Ni14Mo2 (316L); third digit: the coating material for the main material; 1: special asbestos paper ； 2: Flexible graphite strip ； 3: Polytetrafluoroethylene ； 4: Special non-asbestos board; fourth digit: material of the inner ring – 0: no inner ring ； 1: Low-carbon steel (20#) ； 2: 0Cr18Ni9 (304) ； 3: 0Cr17Ni12Mo2 (316) ； 4:00Cr17Ni14Mo2 (316L) 38. What are the components in reciprocating compressors that wear out most easily? Valve plates, springs, gaskets, copper sleeves, crankshafts, bearing shells, piston rings, pistons, cylinder liners, packing, support rings, etc. 39. Bearing grades are arranged from low to high. Is grade B a low grade or the highest grade? G, E, D, C, B. For B, which is grade 40, does the perimeter of the V-belt refer to the outer perimeter or both the outer and inner perimeters? What is the angle of the V-belt in degrees? Inner perimeter, angle of 40±1 degrees. What are the common faults and their causes in rolling bearings? 1) Bearing overheating: (1) Insufficient lubricant supply or incorrect lubricant type (2) Presence of debris inside (3) Incorrect installation ； 2) Abnormal sound: (1) Spalling or damage to the bearing raceways; (2) Loose brackets; (3) Severe lack of oil in the bearing; (4) Pitting on the raceways and steel balls ； 3) Poor transmission flexibility: (1) Loose or faulty seals and other accessories attached to the bearings; (2) Bearings stuck due to oil or dirt; (3) Improper fit between the inner and outer rings of the bearings and the bearing housing – either too loose or too tight. 42. Large motors cannot be started continuously; what is the maximum number of times this can be done? It cannot exceed three times. The interval between each of the three sessions should be 30 minutes, and after three sessions, the interval should be 4 hours. If the vehicle cannot be brought to a stop while parking, do not press the start button again; instead, contact an electrician promptly. 43. What are special equipment? Special equipment refers to eight major categories of devices and facilities that pose a significant risk to personal and property safety, including boilers, pressure vessels (including gas cylinders), pressure pipelines, elevators, lifting machinery, passenger cableways, large-scale amusement facilities, and special motor vehicles used within sites (factories), as well as other special equipment specified by laws and administrative regulations as falling under the scope of this law. 44. What is a fixed-pressure vessel? Fixed pressure vessels refer to enclosed devices that hold gases or liquids and are subjected to a certain pressure; their scope is defined as (1) a maximum operating pressure of 0.1 MPa (gauge pressure) or greater ； (2) Volume greater than or equal to 30 L and inner diameter (for non-circular cross-sections, it refers to the largest geometric dimension of the internal boundaries) ； (3) The medium contained is a gas, a liquefied gas, or a liquid with a maximum operating temperature equal to or higher than its standard boiling point. 45. What is the classification of pressure vessels and the determination of pressure grades? Based on the principle of their 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 classification is as follows: 1) Reaction pressure vessel (code R). 2) Heat exchange pressure vessels (code E); 3) Separation pressure vessels (code S); 4) Storage pressure vessels (code C, with spherical tanks coded as B). Based on the design pressure (P) of the pressure vessels, they are classified into four pressure categories: low pressure, medium pressure, high pressure, and ultra-high pressure. The specific classifications are as follows: 1) Low-pressure vessels: P = 0.1–1.6 Mpa ； 2) Medium-pressure vessel P=1.6～10Mpa ； 3) High-pressure vessel P=10～100Mpa ； 4) Ultra-high pressure vessels with P > 100 Mpa. 46. What is a pressure pipeline? It refers to tubular devices that use a certain pressure to transport gases or liquids; such devices are defined as those with a maximum operating pressure of 0.1 MPa (gauge pressure) or more, where the medium is a gas, liquefied gas, steam, or a liquid that is flammable, explosive, toxic, corrosive, and has a maximum operating temperature equal to or higher than its standard boiling point, and whose nominal diameter is 50 mm or more. Except for pipes with a nominal diameter of less than 150 mm and a maximum operating pressure of less than 1.6 MPa (gauge pressure), as well as the pipes that form part of the equipment used for transporting non-toxic, non-flammable, and non-corrosive gases. Pressure pipelines are classified into: 1) Long-distance pipelines (GA category), 2) Utility pipelines (GB category), 3) Industrial pipelines (GC category). 1) GA category (Long-distance pipelines): Long-distance (oil and gas) pipelines refer to those used for transporting oil and gas as commercial materials between production sites, storage facilities, and users; they are divided into GA1 and GA2 grades. 　　 1) GA1 grade – Long-distance pipelines that meet one of the following conditions are classified as GA1 grade: ① Long-distance gas pipelines with a design pressure of 4.0 MPa or higher (gauge pressure, the same below); ② Long-distance oil pipelines with a design pressure of 6.3 MPa or higher. 　　 2) GA2 level —— Long-distance pipelines other than GA1 level. (2) 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 grade and GB2 grade. 　　 1) GB1 grade — Gas pipelines. 　　 2) GB2 level — Thermal pipelines. (3). GC category (industrial pipelines): Industrial pipelines refer to the process pipelines, utility pipelines, and other auxiliary pipelines owned by enterprises and institutions and used for transporting process media. They are classified into GC1 grade, CC2 grade, and GCD grade. 1) GC1 grade – Process pipelines that meet one of the following conditions are classified as GC1 grade: ① Process pipelines that transport media with an acute toxicity level of Category 1 as specified in the “Catalogue of Hazardous Chemicals”, gas media with acute toxicity of Category 2, or liquid media with acute toxicity of Category 2 whose operating temperature is higher than their standard boiling point; ② Process pipelines that transport flammable gases of Classes A and B or flammable liquids of Class A (including liquefied hydrocarbons), and whose design pressure is 4.0 MPa or higher; ③ Process pipelines that transport fluid media, with a design pressure of 10.0 MPa or higher, or with a design pressure of 4.0 MPa or higher and an operating temperature of 400°C or higher. 2) GC2 grade – Industrial pipelines that meet one of the following conditions are classified as GC2 grade: ① Process pipelines other than those of GC1 grade; ② Refrigeration pipelines. 3) GCD grade – Power pipelines.