Pressure Vessel Design Review Question Bank (Short Answer Questions 1/3)

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4. Short-answer questions (answers are for reference only)
4-1 The main types of overpressure relief devices used in pressure vessels are as follows:
A. Safety valves
B. Vent valves
C. Burst disc safety devices
D. Combined devices of safety valves and burst disc safety devices
Answer: A, C, D
Explanation: GB150.1-2011, Clause P17 B1.2

4-2 When there are no special requirements for overpressure relief devices in pressure vessels, the preferred choices are:
A. Safety valves
B. Burst disc safety devices
C. Combined devices of burst disc safety devices and safety valves
Answer: A
Explanation: GB150.1-2011, Clause B.3.6

4-3 In what situations should burst disc safety devices be used?
A. Rapid increase in pressure
B. Slow increase in pressure
C. High sealing requirements
D. Low sealing requirements
E. The material inside the vessel may cause the safety valve to fail
F. Other situations where safety valves are not suitable
Answer: A, C, E, F
Explanation: GB150.1-2011, Clause B.3.7

4-4 What components make up a burst disc safety device? A. Blowing disc B. Clamp C. Base Answer: A, B Explanation: According to GB150.1-2011, clause B.5.1, items 4-5, blowing disc safety devices are suitable for situations where pressure increases rapidly A. Correct B. Incorrect Answer: A Explanation: According to clause B.5.2, item 4-6 of GB150.1-2011, rupture disc safety devices can be used alone in situations where the toxicity level of the medium is extremely high or highly hazardous, or in cases involving explosive substances and liquefied petroleum gas. A. Correct B. Incorrect Answer: B Explanation: According to clause B.5.3, items 4–7 of GB150.1-2011, safety valves can be used alone in situations where pressure increases rapidly? A. Correct B. Incorrect Answer: B Explanation: According to clause B.4.2, point 4-8 of GB150.1-2011, safety valves should not be used alone in situations where the sealing surfaces between the valve seat and the valve disc may become stuck due to the medium, or where the medium may form crystals A. Correct B. Incorrect Answer: A Explanation: According to clause B.4.3, item 4-9 of GB150.1-2011, in what applications are safety valves applicable? A. Contains solid particles B. Does not contain solid particles C. Low viscosity D. High viscosity. Answer: B, C. Explanation: According to GB150.1-2011, clause B.4.1, 4-10, are pressure vessels with a design temperature below -20°C considered low-temperature vessels? A. Correct B. Incorrect Answer: B Explanation: According to clause E.1.1, item 4-11 of GB150.3-2011, what are the common types of failure that can occur in cryogenic vessels at low temperatures? A. Plastic failure B. Brittle failure C. Fatigue failure D. Creep failure Answer: B Explanation: According to the “Training Manual for Pressure Vessel Design Engineers”, page 3624-12, in the design of low-temperature pressure vessels, which of the following structural considerations are necessary? A. The structure should be as simple as possible. B. The connection between the nozzles and the vessel shell should be smooth; the inner surface at the ends of the nozzles should be rounded. C. Gaskets should be used at the vessel’s supports or legs. D. Excessive temperature gradients should be avoided. E. Sudden changes in the structural shape should be avoided as much as possible. F. The vessel flanges and nozzle flanges must be of the butt-welded type. Answer: ABCDE Explanation: Per GB150.3-2011, clause E.2.3, item 4-13, a “low-temperature, low-stress condition” refers to situations where carbon steel and low-alloy steel vessels or their pressure-bearing components are designed for temperatures below -20°C, but the maximum overall membrane and bending stresses experienced by these components are less than or equal to 1/6 of the yield strength of the steel at normal temperature. A. Correct B. Incorrect Answer: A Explanation: According to clause E.1.4, item 4-14 of GB150.3-2011, when the shell of carbon steel or low-alloy steel containers, or their pressure-bearing components, are used in \"low-temperature and low-stress conditions\", and if the design temperature plus 50°C is still not lower than –20°C, then the regulations applicable to low-temperature containers need not be followed, unless otherwise specified. A. Correct B. Incorrect Answer: A Explanation: According to GB150.3-2011, clause E.1.4, items 4-15, which of the following materials are not suitable for use in low-temperature and low-stress conditions? A. Materials with a minimum standard tensile strength Rm of ≥540 MPA. B. Bolt materials. C. Q235B series steel plates. D. Q345R. Answer: ABC Explanation: Per GB150.3-2011, clause E.2.2, item 4-16, is it permissible not to conduct inspections on the final circumferential sealing welds of cylinders and end caps with a diameter of no more than 800 mm? A. Allowed B. Not allowed Answer: A Explanation: According to clause 10.3.4, item 4-17 of GB150.4-2011, when the final circumferential sealing weld between a cylinder and a head with a diameter of no more than 800 mm cannot be inspected using radiography or ultrasonic testing, gas shielded welding can be used for the root pass welding. A. Correct B. Incorrect Answer: B Explanation: According to GB150.4-2011, clause 10.3.4, item 4-18, for cylindrical vessels and heads with a diameter of no more than 800 mm, when the final circumferential sealing weld cannot be inspected using radiography or ultrasonic testing, a single-sided welded butt joint using gussets is the only acceptable option. A. Correct B. Incorrect Answer: B Explanation: According to clause 10.3.4, item 4-19 of GB150.4-2011, when the strength of the clad material must be taken into account in the design calculations for 4-19 stainless steel clad plates, what level or higher must the adhesion between the clad layer and the base layer reach according to NB/T47002? A. B1 level B. B2 level C. B3 level Answer: B Explanation: According to GB150.1-2011, clause 4.4.3, when designing stainless steel composite plates and it is necessary to take into account the strength of the clad material, the allowable stress [σ] at the design temperature depends on which of the following factors? A. The nominal thickness of the base steel plate and the allowable stress of the base steel plate at the design temperature. B. The effective thickness of the base steel plate and the allowable stress of the base steel plate at the design temperature. C. The nominal thickness of the clad steel plate and the allowable stress of the clad steel plate at the design temperature. D. The effective thickness of the clad steel plate and the allowable stress of the clad steel plate at the design temperature. Answer: AC Explanation: According to GB150.1-2011, clause 4.4.3, for stainless steel composite plates, when the strength of the clad material needs to be considered in the design, the formula for calculating the allowable stress [σ] at the design temperature is as follows: A. Correct B. Incorrect Answer: A Explanation: According to GB150.1-2011, clause 4.4.3, the hydrostatic test pressure PT for internal pressure vessels is determined using the following formula: PT = 1.25 × [σ] / [σ]t, where P represents the design pressure in MPa, and [σ] represents the allowable stress of the material at the test temperature in MPa ； [σ]t ----- Allowable stress of the cylinder material at the design temperature, MPa ； A. Correct B. Incorrect Answer: A Explanation: According to GB150.1-2011, clause 4.6.2.2, point 4-23, for pressure vessels under internal pressure, vessels under external pressure, and vacuum vessels, hydraulic testing is required. A. Pressure vessels under internal pressure are tested using internal pressure. B. Vessels under external pressure and vacuum vessels are tested using external pressure. C. Vessels under external pressure and vacuum vessels are tested using internal pressure. Answer: AC Explanation: According to GB150.1-2011, clause 4.6.1.6, point 4-25, water alone may be used as the liquid for hydraulic testing of vessels. A. Correct B. Incorrect Answer: B Explanation: According to GB/T150.4-2011, clause 11.4.9.2, other testing liquids that do not pose a risk can also be used if necessary, but the temperature of such liquids must be below their flash point or boiling point, and reliable safety measures must be in place. P3384-26 For which of the following materials used in vessel construction must the temperature of the liquid used for hydraulic testing be at least 5°C? A. Q345R B. Q245R C. 07MnMoV R D. Q370R Answer: ACD Explanation: According to GB/T150.4-2011, P338, clause 11.4.9.34-27, the temperature of the liquid used for hydraulic testing of low-temperature vessels must be at least the impact test temperature of the vessel’s material and welding joints, whichever is lower, plus 20°C. A. Correct B. Incorrect Answer: B Explanation: According to GB/T150.4-2011, clause 11.4.9.3, the temperature should be the impact test temperature of the vessel’s material and welding joints, whichever is higher, plus 20°C. 4-28 Under which of the following circumstances can pneumatic testing be used as a substitute for hydraulic testing? A. The container’s volume is too large to withstand the weight of water. B. Pneumatic testing takes less time than hydraulic testing. C. The structure is complex, and hydraulic testing is not sufficient to fully verify the pressure testing requirements for all parts. D. Due to design considerations, water is not suitable (for example, it is not allowed for test fluid to remain inside the container). E. Other insurmountable difficulties, such as difficulties in supplying water to large containers. Answer: A, C, D, E. Explanation: TSG 21-2016, Section 3.2.12.3. 4-29 For vessels that are not suitable for hydrostatic testing, pneumatic testing can be used as a substitute for hydraulic testing. During the pressure test, the pressure should be increased gradually; when it reaches 50% of the specified test pressure, it should be raised in steps to the final test pressure at a rate of approximately (   ) per step. A.5% B.15% C.10% D.20% Answer: C Explanation: According to GB/T150.4-2011, section 11.4.10.5 4-30, during the pneumatic pressure test, the pressure is increased gradually until it reaches the test pressure, after which the pressure is maintained for a sufficient length of time to conduct inspections. If there is no air leakage and no visible abnormal deformation, it is considered qualified. A. True B. False Answer: B Explanation: GB/T150.4-2011 11.4.10.6 P338 For pressure vessels after pressure and airtightness tests, they are considered qualified if they meet the following conditions: 1) No abnormal noises during the test; 2) No visible deformation; 3) No air leakage as detected by soap solution or other leak detection methods. 4-31 A gas-liquid combined pressure test can replace the airtightness test. A. True B. False Answer: B Explanation: Container Construction Technology P155, clause 19.2.5. 4-32 When the volume of the vessel is too large and the foundation cannot support the weight of water, making a hydraulic test impossible, and when a pneumatic test is too dangerous or time-consuming, a gas-liquid combined pressure test can be used. A. Correct B. Incorrect Answer: A Explanation: According to Container Construction Technology, page P148, section 19.1.2.3, point 4-33, the amount of water used for the gas-liquid combined pressure test is determined by the designer based on experience. A. Correct B. Incorrect Answer: B Explanation: The maximum weight of liquid that can be tolerated should be determined based on the basic load-bearing capacity, and this value should be used as a basis for determining the amount of water to be filled in. 4-34 Under what circumstances is a leak test required? A. When a pressure test cannot be carried out. B. When the toxicity of the medium is extremely high or highly hazardous. C. When design requirements prohibit even minor leaks. Answer: BC. Explanation: GB/T150.1-2011, 4.7.2, P15 – For pressure vessel integrity tests, safety accessories must be installed in their entirety. A. Correct. B. Incorrect. Answer: A. Explanation: TSG21-2016, P35, 4.1.10.14–36 – An integrity test should be conducted after a hydraulic test. If a leak is detected during the airtightness test, the leak should be repaired and then the airtightness test repeated; it is considered satisfactory if no leak is found upon retesting. A. Correct B. Incorrect Answer: A Explanation: According to GB/T150.4-2011, clause 11.5.3.4 4-37, edge stress has several characteristics. A. 1 B. 2 C. 3 D. 4 Answer: B Explanation: (1) Self-limiting nature: Edge stress arises in order to ensure deformation compatibility between adjacent elements; when this stress reaches the material’s yield point, plastic flow occurs in the material, thereby enabling deformation compatibility to be maintained. Once the deformation requirement is met, the plastic flow of the material automatically ceases. Therefore, its stress and strain energy are automatically limited. (2) Locality: In general edge stresses, longitudinal bending stress is predominant, but its range of influence is limited, decreasing rapidly as one moves away from the edge. \"Mechanical Fundamentals of Pressure Vessel Design and Their Standard Application\", P1354-38: Edge stress arises as a result of the need to ensure deformation compatibility among adjacent elements. When this stress reaches the material’s yield point, plastic flow occurs in the material, thereby enabling deformation compatibility to be achieved. Once the deformation requirement is met, the plastic flow of the material automatically ceases. This property is referred to as the A. finiteness B. self-limiting nature C. local nature D. limitation of edge stress. Answer: B. Explanation: As in question 4-39 above, edge stress decreases rapidly as one moves away from the edge. For a cylinder, at what distance from the edge does the edge bending stress drop to 5% of the maximum stress value? R---cylinder radius, δ---cylinder thickness. A. 2*(R*δ)½ B. 2.5*(R*δ)½ C. 3*(R*δ)½ D. 3.5*(R*δ)½ Answer: B. Explanation: Engineer Training Manual – Basic Knowledge of Components, P175; 7.9.1 Stress in Thin Circular Plates. A thin circular plate is one whose thickness δ to diameter D ratio falls within the following range: A. 0.01≤δ/D≤0.2 B. 0.01≤δ/D＜0.2 C. 0.01＜δ/D＜0.2 D. 0.01＜δ/D≤0.2 Answer: C. Explanation: A thin circular plate is defined as one whose thickness δ to diameter D ratio is between 0.01 and 0.2. \"Mechanical Foundations of Pressure Vessel Design and Their Standard Application\", P104, Section 7.2, point 4-41: The deflection of a thin plate under load is much smaller than the plate thickness δA. A. True B. False. Answer: A. Explanation: The deflection of a thin plate under load is indeed much smaller than its thickness δ; the theory of small deflections for thin plate bending is generally applied in this case. Source: \"Mechanical Foundations of Pressure Vessel Design and Their Standard Application\", P103. Small deflection assumption: 4-42 The theoretical basis for the stress analysis of thin plates is the small deflection theory of plate bending. A. Correct B. Incorrect Answer: A Explanation: Basic knowledge in engineering training tutorials, components – P163, 7.7.1 Regarding long and short cylinders under external pressure: 4-43 A cylinder whose calculated external pressure length is greater than its critical length is considered a short cylinder; conversely, a cylinder whose calculated external pressure length is less than its critical length is regarded as a long cylinder. A. Correct B. Incorrect Answer: B Explanation: Oblong cylinder: A cylinder whose calculated length is greater than the critical length. The end boundaries or caps of the long cylinder do not provide any reinforcing support for its middle section; its critical pressure is independent of the cylinder length. When it loses stability, the cross-section changes from circular to wavy, with the wave number equal to 2. Short cylinder: A cylinder whose calculated length is less than the critical length. The end boundaries or heads of a short cylinder can provide reinforcing support for its middle section, and its critical pressure is inversely proportional to the length of the cylinder. Upon instability, the cross-section changes from circular to wavy, with a wave number greater than 2. \"Mechanical Foundations of Pressure Vessel Design and Their Standard Application\", P147–1464-44: When a long cylinder becomes unstable, how many wave patterns appear on its cross-section? A. 2 B. More than 2 C. 4 D. More than 4. Answer: A. Explanation: As mentioned earlier regarding externally pressurized long cylinders and short cylinders (4-45), what is the purpose of using reinforcing rings in the design of externally pressurized cylinders? A. To reduce the calculated length of the cylinder B. To increase the strength of the cylinder C. To transform a long cylinder into a short one D. To enhance the stability of the cylinder. Answer: ACD. Explanation: Reinforcing rings are used on externally pressurized cylinders to turn them into short cylinders or to reduce their calculated length; both approaches serve to improve the stability of the cylinder. \"Beginner’s Notes\" 4-46: The flange torque is shared by the flange ring and the conical neck. A. Correct B. Incorrect. Answer: B. Explanation: A flange is supported by three components that make up it: the flange ring, the conical neck, and the cylinder. The load-bearing ratio of the three is proportional to their rotational stiffness; in other words, the greater the stiffness, the higher the load-bearing ratio. By increasing the size of the flange cone neck, its rotational stiffness is enhanced, which increases its load-bearing capacity. As a result, the boundary forces and boundary moments between the cone neck and the flange ring increase, namely the boundary forces at the end of the cone neck. \"Beginner’s Notes\" 4-47: Increasing the thickness of the flange ring – which of the following statements are correct? A. The load-bearing capacity of the flange ring increases. B. The load-bearing capacity of the conical neck and the cylinder also increases. C. The rotational stiffness of the flange ring is improved. Answer: AC. Explanation: Increasing the thickness of the flange improves its rotational stiffness, which in turn increases its load-bearing capacity; as a result, the load-bearing capacity of the flange’s conical neck and cylindrical sections decreases. Source: “Pressure Vessel Engineer’s Guidebook”, Flange section. 4-48 By increasing the thickness of the flange ring, the boundary moment and boundary force acting on the flange ring will decrease. Therefore, the axial stress, radial stress, and hoop stress of the flange all decrease. A. Correct B. Incorrect Answer: B Explanation: Increasing the thickness of the flange improves the rotational stiffness of the flange ring, which in turn increases its load-bearing capacity; as a result, the load-bearing capacity of the flange’s conical and cylindrical sections decreases. Specifically, the boundary moment and boundary force between the conical neck and the flange ring will decrease, thereby reducing the radial bending moment acting on the inner edge of the flange ring. At the same time, the bending cross-sectional area per unit circumferential length of the flange ring increases due to its relationship with the flange thickness being quadratic, but the rotational stiffness of the flange increases due to its relationship with the flange thickness being cubic; as a result, the hoop stress decreases. However, when the stiffness of the flange ring is comparable to that of the conical neck, an increase in hoop stress may also occur. The axial bending stress in the conical neck decreases due to the reduction in boundary torque. In the flange section of the \"Guidance Manual for Pressure Vessel Engineers\", TSG21-2016 \"Regulations on Pressure Vessels\", Table 2-2 \"Indicators for elongation after fracture of steel plates\" – 4-49, the criterion used to determine the plasticity of common metals is A. hardness, B. strength, C. elongation after fracture, or D. yield limit. The answer is C. Explanation: According to the definitions in mechanics of materials, the ability of a metal to undergo irreversible permanent deformation before fracturing is known as plasticity; the commonly used criteria for assessing plasticity are elongation after fracture and reduction of area. According to Table 2-2 in Page P8 of TSG21-2016 \"Code for Fixed Pressure Vessels\", for 4-50 grade carbon steels and low-alloy steels, the higher the tensile strength, the greater the elongation after fracture. A. Correct B. Incorrect Answer: B Explanation: According to Table 2-2 “Elongation after fracture criteria for steel plates” on page P8 of TSG21-2016 “Regulations on Pressure Vessels”, the higher the tensile strength of carbon steel and low-alloy steel, the lower their plasticity. A. Correct B. Incorrect Answer: B Explanation: What are the requirements for carbon steel used in simple pressure vessels as stated in Table 2-2 “Elongation after fracture criteria for steel plates” on page P8 of TSG21-2016 “Regulations on Pressure Vessels”? 4- What are the specific requirements for carbon steel used in simple pressure vessels 52? A. Supply condition and chemical composition B. Chemical composition and mechanical properties C. Supply condition, chemical composition, and mechanical properties D. Supply condition, chemical composition, and minimum tensile strength Value: D Explanation: TSG21-2016 P10 2.2.1.8 What are the requirements for carbon steel used in simple pressure vessels? 4- What are the chemical composition requirements for carbon steel used in simple pressure vessels? A. C≤0.20%, S≤0.045%, P≤0.045% B. C≤0.25%, S≤0.045%, P≤0.045% C. C≤0.25%, S≤0.035%, P≤0.035% D. C≤0.20%, S≤0.035%, P≤0.035% Answer: B Explanation: TSG21-2016 P10 2.2.1.8 The minimum standard tensile strength of carbon steel used in simple pressure vessels at room temperature is (). A.≤540MP      AB.