Design method of spherical storage tank based on damage mode logic chain

Abstract

The invention belongs to the technical field of spherical storage tank design, and particularly relates to a spherical storage tank design method based on a damage mode logic chain. The method comprises the following steps: S1, determining design conditions of a spherical tank; s2, determining design parameters of the spherical tank according to design conditions of the spherical tank; s3, identifying a damage mode of the spherical tank according to design conditions and design parameters of the spherical tank; s4, determining special technical requirements of the spherical tank according to the damage mode of the spherical tank; in the design process, dynamic association is formed among all the steps, and when a previous parameter is changed, linkage adjustment is carried out on a later parameter. According to the method, a complete logic chain from design conditions to special technical requirements is constructed, dynamic association is formed among the parameters, when a certain parameter is changed, follow-up parameters are subjected to automatic linkage adjustment, omission caused by manual one-by-one modification is avoided, and the efficiency and accuracy of design change are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of spherical storage tank design technology, and particularly relates to a spherical storage tank design method based on damage mode logic chain. Background Technology

[0002] Spherical storage tanks, with their spherical structure, feature a small surface area, material savings, and high pressure resistance. Their uniform stress distribution allows for efficient storage of high-pressure gases or liquids (such as LNG and oil). Constructed from high-strength, corrosion-resistant steel, they offer high safety, significantly reducing the risk of leaks and explosions, thus ensuring industrial and environmental safety. Compared to other tank types, they offer advantages such as high space utilization and low maintenance costs, making them an indispensable key storage facility in the energy and chemical industry.

[0003] Many designers will improve certain technical specifications based on their experience to better control the risks of spherical storage tanks throughout their lifespan. The above technical requirements are special technical requirements. The formulation of special technical requirements mainly relies on the experience of the design team, and there is no clear way or method for proposing special technical requirements.

[0004] In addition, designers often encounter design changes during the design process. If a designer changes one parameter, it may affect many other parameter changes, and redesigning is time-consuming and laborious. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, this invention provides a spherical storage tank design method based on a damage mode logic chain. This invention systematically integrates the originally dispersed design processes by constructing a complete logic chain from design conditions to specific technical requirements.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A design method for spherical storage tanks based on damage mode logic chains includes the following steps: S1. Determine the design conditions of the spherical tank, including: obtaining the installation location of the spherical tank, the name of the stored medium, the nominal volume of the spherical tank and the design service life, determining the representative medium and its corresponding medium characteristics, determining the working temperature, working pressure, hydrogen sulfide content, inner diameter and structural form, and determining the environmental parameters; S2. Based on the design conditions of the spherical tank, determine the design parameters of the spherical tank, including: the basic parameters of the spherical tank, shell material selection, supporting materials, corrosion allowance and wall thickness; S3. Based on the design conditions and parameters of the spherical tank, identify the damage modes of the spherical tank, including: damage mechanism identification and process risk analysis; S4. Determine the special technical requirements for the spherical tank based on its damage mode; During the design process, dynamic relationships are formed between each step. When a parameter in a previous step changes, subsequent parameters are adjusted accordingly.

[0007] Preferably, the representative medium is determined by the name of the medium being stored, including liquefied petroleum gas, propane, propylene, n-butane, isobutane, butene, isobutene, pentane, pentene, liquid ammonia, dimethyl ether, ethylene oxide, ethane, ethylene, carbon dioxide, Freon-23, air, natural gas, oxygen, nitrogen, LNG (i.e., liquefied natural gas), and hydrogen. The operating temperature, operating pressure, and hydrogen sulfide content are all determined by representative media, while the inner diameter and structural form are determined by the nominal volume of the spherical tank. Environmental parameters are determined by the installation location of the spherical tank, including the minimum temperature at the installation location, the basic snow pressure at the installation location, the basic wind pressure at the installation location, and the seismic intensity at the installation location; The characteristics of the medium are determined by representative media, including phase, toxicity hazard level, explosion hazard level, and medium grouping.

[0008] Preferably, in step S2, the basic parameters include design pressure, design temperature, vessel type, weld coefficient, and insulation requirements.

[0009] When a safety valve is installed in the spherical tank, the design pressure is equal to the set pressure. Furthermore, the set pressure is determined as follows: First, assume the set pressure is 1.05-1.1 times the working pressure and calculate the set pressure. When the calculated set pressure is ≥0.18MPa, the set pressure is 1.05-1.1 times the working pressure. When the calculated set pressure is <0.18MPa, the ratio of the set pressure to the working pressure can be appropriately increased, that is, the set pressure is >1.1 times the working pressure. When the spherical tank is not equipped with a safety valve, the design pressure is greater than or equal to the set pressure, and the design pressure is 1.05 times the working pressure.

[0010] The minimum design temperature is determined by the lowest air temperature and operating temperature at the installation location of the spherical tank, including -20℃, -30℃, -40℃, -50℃, -70℃, -100℃ and -196℃; The pressure vessel categories include Class I, Class II, and Class III pressure vessels. When the pressure vessel is classified as Class I, the weld coefficient is 0.85; when the pressure vessel is classified as Class II or Class III, the weld coefficient is 1.0.

[0011] Preferably, in step S2, the step of selecting the shell material is as follows: (1) When the minimum design temperature is ≥-20℃, the default material for the spherical tank is Q370R, and the tank wall thickness is calculated based on the default material. Furthermore, if the calculated tank wall thickness is ≥45mm and the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen and hydrogen, then the tank material is changed to Q490R. If the calculated tank wall thickness is <38mm and the representative medium is liquefied petroleum gas, then the tank material is changed to Q245R or Q345R. (2) When -40℃≤minimum design temperature<-20℃, the default material for the spherical tank is 16MnDR, and the tank wall thickness is calculated based on the default material. Furthermore, if the calculated tank wall thickness is >45mm, and the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen and hydrogen, then the tank material is changed to Q490DRL1. (3) When -50℃≤minimum design temperature<-40℃, the default material for the spherical tank is 15MnNiNbDR, and the tank wall thickness is calculated based on the default material. Furthermore, if the calculated tank wall thickness is >45mm, and the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen and hydrogen, then the tank material is changed to Q490DRL2. (4) When -70℃≤minimum design temperature<-50℃, the material of the spherical tank shall be -70℃ low temperature steel 09MnNiDR; (5) When -196℃≤minimum design temperature<-70℃, the material of the spherical tank shall be austenitic stainless steel (S30803).

[0012] Preferably, in step S2, corrosion allowance = corrosion rate × design life; When the representative medium is one of liquefied petroleum gas, ethylene, ethane, carbon dioxide or Freon-23, the corrosion rate is 0.075 mm / y. When the representative medium is LNG (liquefied natural gas), the corrosion rate is 0.01 mm / y, and the corrosion rate of other representative media is 0.025 mm / y. When the calculated corrosion allowance is ≤1.0mm, the corrosion allowance shall be taken as 1.0mm; When 1.0mm < calculated corrosion allowance ≤ 1.5mm, the corrosion allowance is taken as 1.5mm; When 1.5mm < calculated corrosion allowance ≤ 2.0mm, the corrosion allowance is taken as 2.0mm; When the calculated corrosion allowance is greater than 2.0 mm, the value is rounded up.

[0013] Preferably, in step S3, the damage modes identified based on the damage mechanism include ductile fracture, brittle fracture, low-temperature brittle fracture, mechanical fatigue, reheat cracking, liquid ammonia stress corrosion cracking, wet hydrogen sulfide damage, acidic water corrosion, corrosion under the insulation layer, and atmospheric corrosion.

[0014] The method for process risk analysis is as follows: (1) If the representative medium is in the liquid phase, the spherical tank is at risk of overfilling: the filling operation process should be strictly managed, the filling temperature and the corresponding filling coefficient should be determined, and a liquid level alarm and interlock should be set up. (2) If the representative medium is in the gas phase, the working pressure of the gas spherical tank is prone to fluctuation. The amplitude and frequency of the fluctuation may exceed the amplitude and frequency specified in the design. A reliable pressure monitoring, alarm and control system needs to be set up in the process. (3) If the representative medium is liquefied petroleum gas, there is a risk of excessive hydrogen sulfide content in the spherical tank: the composition and source of liquefied petroleum gas are relatively complex, and the possibility of excessive hydrogen sulfide content is relatively high. (4) If the representative medium is oxygen, the spherical tank is at risk of combustion and explosion: oxygen has a combustion-supporting effect, and combustible residues should be avoided inside the spherical tank. After the spherical tank is derusted, carbon tetrachloride should be used to degrease the parts of the spherical tank (including pipes, manholes, etc.) that come into contact with oxygen. (5) If the representative medium is one of ethylene, ethane, carbon dioxide and Freon-23, the spherical tank is at risk of overpressure: the saturated vapor pressure of high-pressure liquefied gas is greatly affected by the medium temperature. Fluctuations in the medium temperature can easily cause overpressure in the spherical tank. The insulation effect of the insulation layer should be ensured. Therefore, temperature and pressure alarms and interlocks should be set up, and a circulating cooling process should be set up to ensure the stability of the representative medium temperature.

[0015] Preferably, in step S4, the specific technical requirements regarding brittle fracture are as follows: (1) For spherical tank steel plates with wall thickness > 36 mm after quenching and tempering, an additional set of impact tests shall be conducted at 1 / 2 of the steel plate thickness. (2) For steel plates of spherical tanks with a wall thickness of >50mm that have been normalized or normalized and tempered, an additional set of impact tests shall be conducted at 1 / 2 of the steel plate thickness. (3) For spherical tank steel plates with a wall thickness > 36 mm and a standard tensile strength lower limit ≥ 540 MPa, a drop hammer test shall be conducted; (4) When the thickness of the steel plate of the spherical tank after quenching and tempering is >16mm, the ultrasonic testing quality level is Class I; (5) When the thickness of Q370R steel plate is >25mm, the ultrasonic testing quality level is ≥II; when the thickness of Q345R or Q245R steel plate is >36mm, the ultrasonic testing quality level is ≥II. (6) For spherical tank steel plates that have undergone quenching and tempering heat treatment or have a wall thickness > 60 mm, each quenched and tempered heat-treated steel plate shall be subjected to tensile and V-notch impact tests. (7) Magnetic particle testing was performed on the gas-cut bevel surface of spherical tank steel with a standard tensile strength lower limit value ≥540MPa; (8) Grade IV forgings for Class III pressure vessels purchased must be re-inspected; (9) The upper limit of welding line energy for 09MnNiDR is ≤30KJ / cm; the welding line energy for spherical tank steel with a standard tensile strength lower limit of ≥540MPa is ≤35KJ / cm. (10) Low alloy steel with a standard tensile strength lower limit of ≥540MPa shall be subjected to 100% magnetic particle testing in accordance with NB / T 47013.4-2015 or 100% penetrant testing in accordance with NB / T 47013.5-2015 after root cleaning, and the qualified level shall be ≥ Grade I. (11) For butt welds of spherical tanks with a weld joint thickness > 32 mm and a material standard tensile strength lower limit ≥ 540 MPa, the post-heating temperature is 200℃-250℃ and the post-heating time is 0.5h-1.0h; for low alloy steel with a weld joint thickness > 38 mm, the post-heating temperature of butt welds of spherical tanks is 200℃-250℃ and the post-heating time is 0.5h-1.0h. (12) Spherical tanks made of steel with a standard tensile strength lower limit of ≥540MPa, i.e. spherical tanks made of materials with a tendency to delay cracking, shall be subjected to non-destructive testing 36 hours after welding is completed. (13) For spherical tanks with a standard tensile strength lower limit Rm ≥ 540 MPa, the welded joints shall undergo an additional 100% surface inspection after the pressure test; (14) Spherical tanks with a wall thickness > 32 mm and spherical tanks with representative extremely hazardous or highly hazardous media shall undergo overall heat treatment after welding; if the spherical tank is not subjected to overall heat treatment after welding on site, the local welded structure shall be subjected to heat treatment at the manufacturing plant in accordance with the requirements of Clause 7.2.3 of GB / T 12337-2014 "Steel Spherical Storage Tanks"; spherical tanks made of steel with a standard tensile strength lower limit ≥ 540 MPa shall undergo local heat treatment at the manufacturing plant in advance; (15) Spherical tanks made of steel with a standard tensile strength lower limit of ≥540MPa shall be inspected after one year of use.

[0016] Preferably, the specific technical requirements for the destruction of wet hydrogen sulfide in step S4 are as follows: (1) When the representative medium is liquefied petroleum gas, there is a risk of hydrogen sulfide exceeding the standard, and when the wall thickness is >36mm, an additional set of impact tests is added, with samples taken at 1 / 2 of the steel plate thickness. (2) When there is a risk of damage from wet hydrogen sulfide in the spherical tank, increase the impact energy index of the steel plate; (3) When there is a wet hydrogen sulfide destruction mechanism and the hydrogen sulfide content is >500ppm, reduce the sulfur and phosphorus content index of the steel plate. (4) The toxicity of the representative medium is extremely or highly hazardous, or the spherical tank is used in a wet hydrogen sulfide environment, and the ultrasonic testing quality level of the steel plate is ≥ Grade II; (5) The spherical tank is at risk of stress corrosion cracking and the overall heat treatment cannot completely eliminate the welding residual stress. The welded parts should be heat treated first and then the overall heat treatment should be performed after welding. (6) Strictly control the hydrogen sulfide content of the medium; (7) If the nominal thickness of the spherical tank is greater than 50 mm and there is a cracking mechanism during operation, the spherical tank shall be opened for inspection one year after it is put into use.

[0017] Preferably, in step S4, the specific technical requirements for stress corrosion cracking of liquid ammonia are as follows: (1) Spherical tanks are at risk of stress corrosion cracking, so the impact energy index of the steel plate should be increased; (2) The spherical tank is at risk of stress corrosion cracking, and the ultrasonic testing quality level is ≥ II; (3) The spherical tank is at risk of stress corrosion cracking and the overall heat treatment cannot completely eliminate the residual stress of welding. The welded parts should be heat treated first and then the overall heat treatment after welding should be carried out. (4) When stress corrosion cracking of liquid ammonia is present, the water content of liquid ammonia must be ≥0.2%; (5) If the nominal thickness of the spherical tank is greater than 50 mm and there is a cracking mechanism during operation, the spherical tank shall be opened for inspection one year after it is put into use.

[0018] Preferably, in step S4, the specific technical requirements regarding mechanical fatigue are as follows: (1) Improve the impact energy index of steel plates, set the ultrasonic testing quality level to level I, set the manhole forgings to level IV, set other forgings for low temperature use to level IV, conduct tensile and V-notch impact tests on each steel plate, and do not use hard marking; (2) The spherical tank is at risk of mechanical fatigue and the overall heat treatment cannot completely eliminate the residual stress of welding. The welded parts should be heat treated first and then the overall heat treatment after welding should be carried out. (3) If the nominal thickness of the spherical tank is greater than 50 mm and there is a cracking mechanism during operation, the spherical tank shall be opened for inspection one year after it is put into use.

[0019] The specific technical requirements for reheat cracking are: the spherical tank must undergo non-destructive surface testing after heat treatment; Preferably, in step S4, the specific technical requirements regarding low-temperature brittle fracture are as follows: (1) For steel plates designed for temperatures < -40℃, a drop hammer test may be performed. The test shall be conducted in accordance with GB / T 6803-2023 "Drop Hammer Test Method for Non-Plastic Transformation Temperature of Ferritic Steel"; (2) Steel plates with a design temperature < -20℃ (excluding quenched and tempered steel), a steel plate thickness > 20mm, and an ultrasonic testing quality level ≥ II; (3) Welding electrodes for cryogenic containers (spherical tanks made of steel with a design temperature < -20℃) shall be retested in batches for moisture content of the coating or diffusible hydrogen content of the deposited metal; (4) Pressure-bearing components of cryogenic containers (spherical tanks made of steel with a design temperature < -20℃) shall not be marked with hard stamps; (5) Spherical tanks made of steel with a design temperature of <-20℃ shall undergo local heat treatment at the manufacturing plant in advance.

[0020] The advantages of this invention are: (1) This invention takes damage pattern recognition as its core and establishes a complete logical chain for the design of spherical storage tanks together with design conditions, design parameters, and special technical requirements. It also proposes a method for determining special technical requirements related to damage patterns. Through the logical chain, all design conditions, design parameters, and special technical requirements for spherical storage tanks are determined with minimal necessary inputs, combining standard and empirical databases. This ensures that when a parameter in the logical chain is modified, the parameters preceding that parameter remain unchanged, and all other parameters following that parameter will change accordingly. This avoids the problem of oversight caused by parameter changes.

[0021] (2) This invention integrates the originally scattered design processes by constructing a complete logical chain from design conditions to special technical requirements. The parameters are dynamically linked, and when a parameter changes, the subsequent parameters are automatically adjusted in tandem, avoiding omissions caused by manual modification one by one, and significantly improving the efficiency and accuracy of design changes.

[0022] (3) This invention takes damage mode recognition as its core and combines it with process risk analysis to accurately locate the failure mechanisms (such as corrosion, fatigue, stress cracking, etc.) that may occur during the entire life cycle of the storage tank. By reverse deducing the logic chain, targeted special technical requirements are derived, so that the design shifts from "experience-based" to "risk-prevention", which avoids overly conservative design and fills the safety blind spots not covered by the standards.

[0023] (4) This invention integrates standard databases and experience databases, and automatically matches the optimal material selection, wall thickness calculation and other parameters based on the input design conditions (such as medium characteristics and environmental parameters), thereby reducing redundant design.

[0024] (5) The special technical requirements unit of this invention covers all aspects of materials, manufacturing, and inspection. The system automatically generates customized requirements based on the damage mode and can quickly generate documents such as risk assessment reports, manufacturing technical conditions, and installation technical conditions. Compared with the traditional "copy-modify" mode, the technical requirements are more targeted and avoid using redundant indicators or omitting key control points.

[0025] (6) The topology of the logic chain in this invention clearly shows the dependencies between parameters. When design changes occur, the affected nodes are automatically marked to help engineers quickly assess the scope of the impact. For example, after adjusting the medium volume, the system can prompt that the wall thickness calculation, welding process requirements and inspection frequency need to be updated simultaneously to avoid human error.

[0026] (7) The present invention can form a dynamically updated knowledge base, ensuring compliance during the design process while also allowing for convenient access to historical experience, thus shortening the design cycle by more than 30%. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the process of the present invention. Figure 1 .

[0028] Figure 2 This is a schematic diagram of the process of the present invention. Figure 2 . Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0030] like Figures 1-2 As shown, a spherical storage tank design method based on damage mode logic chain includes the following steps: S1. Determine the design conditions for the spherical tank. 1. Location, Medium, and Volume: Users input the installation location of the spherical tank, the name of the stored medium, the nominal volume of the spherical tank, the design service life, and whether analytical design is required. The nominal volume of the spherical tank is in m³, and the provided nominal volume options include: 50, 120, 200, 400, 650, 1000, 1500, 2000, 3000, 4000, 5000, 6000, 8000, 10000, 12000, 15000, 18000, 20000, 23000, and 25000.

[0031] 2. Representative media: The representative media are determined based on the media name entered by the user. The representative media include: liquefied petroleum gas, propane, propylene, n-butane, isobutane, butene, isobutene, pentane, pentene, liquid ammonia, dimethyl ether, ethylene oxide, ethane, ethylene, carbon dioxide, Freon-23, air, natural gas, oxygen, nitrogen, LNG and hydrogen.

[0032] 3. Design conditions also include operating temperature (°C), operating pressure (MPa), hydrogen sulfide content (ppm), inner diameter (mm), and structural form.

[0033] The operating temperature, operating pressure, and hydrogen sulfide content are all determined by the representative medium. The inner diameter and structural form are determined according to the nominal volume of the spherical tank, referring to the standard GB / T 17261-2011 "Types and Basic Parameters of Steel Spherical Storage Tanks". Regarding the structural form, if both the segmented and hybrid types are available for the same nominal volume, the hybrid type is selected by default. If multiple support pillars are available, the option with fewer pillars is selected by default. However, if the representative medium of the spherical tank is liquid (liquefied petroleum gas), the option with more pillars is selected.

[0034] The structural forms include: 8-pillar 3-belt mixed type, 10-pillar 4-belt mixed type, 10-pillar 3-belt mixed type, 12-pillar 4-belt mixed type, 14-pillar 5-belt mixed type, 12-pillar 5-belt mixed type, 16-pillar 5-belt mixed type, 18-pillar 6-belt mixed type, 20-pillar 7-belt mixed type, 4-pillar 3-belt orange-petal type, 5-pillar 3-belt orange-petal type, 6-pillar 3-belt orange-petal type, 8-pillar 4-belt orange-petal type, 8-pillar 5-belt orange-petal type, 10-pillar 5-belt orange-petal type, 12-pillar 5-belt orange-petal type, 12-pillar 6-belt orange-petal type, 14-pillar 6-belt orange-petal type, and 14-pillar 7-belt orange-petal type.

[0035] Table 1 Other design conditions for representative media

[0036] 4. Environmental parameters: These include the minimum air temperature at the installation site, the basic snow pressure at the installation site, the basic wind pressure at the installation site, and the seismic intensity at the installation site. The minimum air temperature, basic snow pressure, and basic wind pressure are determined according to the standard GB 50009-2012 "Load Code for Design of Building Structures" for the installation site (city). The seismic intensity is determined according to the standard GB 50011-2010 (2016 edition) "Code for Seismic Design of Buildings" for the installation site (city).

[0037] 5. Medium characteristics: including phase state, toxicity hazard level, explosion hazard level, and medium grouping. These values ​​are determined using representative media, as shown in Table 2. Table 2. Medium Properties

[0038] S2. Determine the design parameters of the spherical tank.

[0039] 1. Basic parameters: including design pressure, design temperature (minimum / maximum), vessel type, weld coefficient, and insulation requirements.

[0040] (1) Design pressure: When the spherical tank is equipped with a safety valve, the design pressure is equal to the set pressure. Furthermore, the set pressure is determined as follows: First, assume the set pressure is 1.05-1.1 times the working pressure and calculate the set pressure. When the calculated set pressure is ≥0.18MPa, the set pressure is 1.05-1.1 times the working pressure. When the calculated set pressure is <0.18MPa, the ratio of the set pressure to the working pressure can be appropriately increased, that is, the set pressure is >1.1 times the working pressure.

[0041] When the spherical tank is not equipped with a safety valve, the design pressure is 1.05 times the working pressure.

[0042] (2) Minimum design temperature: determined by the lowest air temperature at the installation location and the operating temperature. The minimum design temperature can be selected, including -20℃, -30℃, -40℃, -50℃, -70℃, -100℃ and -196℃.

[0043] The design temperature is determined as shown in Table 3 below: Table 3 Design Temperature Table

[0044] (3) Container category: Based on the media grouping, design pressure, and nominal volume, refer to Appendix A of the standard TSG 21-2016 "Safety Technical Supervision Regulations for Fixed Pressure Vessels" to determine the classification of fixed pressure vessels. The pressure vessel categories I, II, and III can be selected.

[0045] (4) Weld coefficient: For Class II or Class III pressure vessels, the weld coefficient is 1.0; for Class I pressure vessels, the weld coefficient is 0.85.

[0046] 2. Shell Material Selection

[0047] (1) When the minimum design temperature is ≥-20℃, the default material for the spherical tank is Q370R. The wall thickness of the spherical tank is then calculated based on the default material (calculated thickness = design pressure × inner diameter / (4 × allowable pressure × weld coefficient - design pressure). The allowable pressure of Q370R is 193MPa, and the weld coefficient is 1.0). Furthermore, if the calculated wall thickness of the spherical tank is ≥45mm, and the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen, and hydrogen, then the material for the spherical tank is changed to Q490R. If the calculated wall thickness of the spherical tank is <38mm, and the representative medium is liquefied petroleum gas, then the material for the spherical tank is changed to Q245R or Q345R.

[0048] (2) When -40℃≤minimum design temperature<-20℃, the default material for the spherical tank is 16MnDR, and the wall thickness of the spherical tank is calculated based on the default material. Furthermore, if the calculated wall thickness is thick (>45mm) and the representative medium has no possibility of stress corrosion cracking (the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen and hydrogen), then the material of the spherical tank is changed to Q490RL1.

[0049] (3) When -50℃≤minimum design temperature<-40℃, the default material for the spherical tank is 15MnNiNbDR, and the wall thickness of the spherical tank is calculated based on the default material. If the calculated wall thickness is thick (>45mm) and the representative medium has no possibility of stress corrosion cracking (the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen and hydrogen), the material of the spherical tank is changed to Q490DRL2.

[0050] (4) When -70℃≤minimum design temperature<-50℃, the material of the spherical tank shall be -70℃ low temperature steel 09MnNiDR.

[0051] (5) When -196℃≤minimum design temperature<-70℃, the material of the spherical tank shall be austenitic stainless steel (S30803).

[0052] 3. Supporting materials, as shown in Table 4 below: Table 4. List of Supporting Materials

[0053] 4. Corrosion allowance

[0054] (1) Determine the corrosion rate: Liquefied petroleum gas is susceptible to acidic water corrosion, and there is a high probability of excessive hydrogen sulfide. Ethylene, ethane, carbon dioxide, and Freon-23 spherical tanks have a cold insulation layer, which may lead to corrosion under the cold insulation layer. Therefore, when the representative medium is one of liquefied petroleum gas, ethylene, ethane, carbon dioxide, and Freon-23, the corrosion rate is 0.075 mm / y; when the representative medium is LNG, the corrosion rate is 0.01 mm / y; and the corrosion rate of other representative media is 0.025 mm / y. (2) Determine the corrosion allowance: Corrosion allowance = corrosion rate × design life; When the calculated corrosion allowance is ≤1.0mm, the corrosion allowance shall be taken as 1.0mm; When 1.0mm < calculated corrosion allowance ≤ 1.5mm, the corrosion allowance is taken as 1.5mm; When 1.5mm < calculated corrosion allowance ≤ 2.0mm, the corrosion allowance is taken as 2.0mm; When the calculated corrosion allowance is greater than 2.0 mm, the value is rounded up.

[0055] 5. Wall thickness calculation

[0056] (1) Allowable stress lookup: If analysis and design are to be performed, the allowable stress is to be looked up from GB / T 4732.1~4732.6-2024 "Analysis and Design of Pressure Vessels" based on the shell material and design temperature. If analysis and design are not to be performed, the allowable stress is to be looked up from GB / T 150.1~150.4-2024 "Pressure Vessels" based on the shell material and design temperature.

[0057] (2) Calculate the wall thickness according to GB / T 12337-2014 "Steel Spherical Storage Tanks". If the representative medium is liquid, hydraulic pressure should be considered. Calculated thickness = design pressure × inner diameter / (4 × allowable stress × weld coefficient - design pressure).

[0058] (3) Nominal thickness = calculated thickness + corrosion allowance + negative deviation of steel thickness (0.3mm), round the result upward and add 1mm.

[0059] S3. Identify the damage patterns of the spherical tank.

[0060] 1. The conditions for identifying the damage mechanism are shown in Table 5 below: Table 5. Damage Mechanism Identification Criteria

[0061] 2. Process Risk Analysis

[0062] (1) If the representative medium is liquid, the spherical tank is at risk of overfilling. The filling operation process should be strictly managed, the filling temperature and the corresponding filling coefficient should be determined, and a liquid level alarm and interlock should be set.

[0063] (2) If the representative medium phase is gas, the working pressure of the gas spherical tank is prone to fluctuation. The amplitude and frequency of the fluctuation may exceed the amplitude and frequency specified in the design. A reliable pressure monitoring, alarm and control system should be set up in the process.

[0064] (3) If the representative medium of the spherical tank is liquefied petroleum gas, then the spherical tank is at risk of exceeding the standard for hydrogen sulfide content. The composition and source of liquefied petroleum gas are relatively complex, and its hydrogen sulfide content is more likely to exceed the standard.

[0065] (4) If the representative medium of the spherical tank is oxygen, the spherical tank is at risk of combustion and explosion. Oxygen has a combustion-supporting effect, so combustible residues inside the spherical tank should be avoided. After the spherical tank is derusted, carbon tetrachloride should be used to degrease the parts of the inner wall of the spherical tank (including pipes, manholes, etc.) that come into contact with oxygen.

[0066] (5) If the representative medium of the spherical tank is one of ethylene, ethane, carbon dioxide and Freon-23, the spherical tank is at risk of overpressure. The saturated vapor pressure of high-pressure liquefied gas is greatly affected by the medium temperature. Fluctuations in the medium temperature can easily cause overpressure in the spherical tank. The insulation effect of the insulation layer should be ensured, temperature and pressure alarms and interlocks should be set up, and a circulating cooling process should be set up to ensure the stability of the medium temperature.

[0067] S4. Determine the special technical requirements for the spherical tank.

[0068] 1. The specific technical requirements for brittle fracture are as follows: (1) For heat-treated spherical tank steel plates with a wall thickness > 36 mm (material grade Q490R or Q490DRL1 or Q490DRL2), an additional set of impact tests is conducted by sampling at 1 / 2 of the steel plate thickness.

[0069] (2) For steel plates of spherical tanks with wall thickness > 50 mm that have been normalized or normalized and tempered (material grade is one of Q370R, Q345R, Q245R, 16MnDR, 15MnNiDR, 15MnNiNbDR and 09MnNiDR), an additional set of impact tests shall be conducted by sampling at 1 / 2 of the steel plate thickness.

[0070] (3) For spherical tank steel plates with a wall thickness of >36mm and a standard tensile strength lower limit of ≥540MPa, an additional drop hammer test shall be conducted.

[0071] (4) When the thickness of the steel plate of the spherical tank after heat treatment is >16mm, the ultrasonic testing quality level is Class I.

[0072] (5) When the thickness of Q370R steel plate is >25mm, the ultrasonic testing quality level is ≥II. When the thickness of Q345R or Q245R steel plate is >36mm, the ultrasonic testing quality level is ≥II.

[0073] (6) For heat-treated spherical tank steel plates or spherical tank steel plates with a thickness > 60 mm, each heat-treated spherical tank steel plate shall be subjected to tensile and V-notch impact tests.

[0074] (7) The gas-cut bevel surface of spherical tank steel with a standard tensile strength lower limit of ≥540MPa shall be subjected to magnetic particle testing.

[0075] (8) Grade IV forgings for Class III pressure vessels purchased need to be re-inspected.

[0076] (9) The welding heat input of spherical tank steel with a standard tensile strength lower limit of ≥540MPa should be ≤35KJ / cm. It is recommended that the welding heat input of 09MnNiDR should be ≤30KJ / cm.

[0077] (10) Low alloy steel with a standard tensile strength lower limit of ≥540MPa must undergo 100% magnetic particle testing in accordance with NB / T 47013.4-2015 or 100% penetrant testing in accordance with NB / T 47013.5-2015 after root cleaning, and the qualified level must be ≥ Grade I.

[0078] (11) For butt welds of spherical tanks with a weld joint thickness > 32 mm and a material standard minimum tensile strength ≥ 540 MPa, the post-heating temperature should be 200℃-250℃ and the post-heating time should be 0.5h-1.0h. For butt welds of low alloy steel spherical shells with a weld joint thickness > 38 mm, the post-heating temperature should be 200℃-250℃ and the post-heating time should be 0.5h-1.0h.

[0079] (12) Spherical tanks made of steel with a standard tensile strength lower limit of ≥540MPa shall be subjected to non-destructive testing 36 hours after welding.

[0080] (13) The welded joints of spherical tanks with a standard tensile strength lower limit of ≥540MPa shall undergo an additional 100% surface inspection after the pressure test.

[0081] (14) Spherical tanks with a wall thickness > 32 mm shall undergo post-weld overall heat treatment; if the representative medium is an extremely hazardous or highly hazardous medium, post-weld overall heat treatment shall be performed; if the spherical tank does not require on-site post-weld overall heat treatment, the manufacturer shall perform post-weld heat treatment of the local welded structure in accordance with the requirements of Clause 7.2.3 of GB / T 12337-2014; spherical tanks made of high-strength steel materials need to undergo local heat treatment in advance at the manufacturer.

[0082] (15) Spherical tanks made of steel with a standard tensile strength lower limit of ≥540MPa shall be opened for inspection one year after they are put into use.

[0083] 2. The specific technical requirements for the destruction of wet hydrogen sulfide are as follows: (1) When the representative medium is liquefied petroleum gas, there is a risk of hydrogen sulfide exceeding the standard. When the wall thickness is >36mm, an additional impact test is performed by sampling at 1 / 2 of the steel plate thickness.

[0084] (2) When there is a risk of damage from wet hydrogen sulfide in the spherical tank, increase the impact energy index of the steel plate.

[0085] (3) When there is a wet hydrogen sulfide destruction mechanism and the hydrogen sulfide content is >500ppm, reduce the sulfur and phosphorus content index of the steel plate.

[0086] (4) The toxicity level of the representative medium is extremely or highly hazardous, or the spherical tank is used in a wet hydrogen sulfide environment, and the ultrasonic testing quality level of the steel plate is ≥ Grade II.

[0087] (5) When there is a risk of stress corrosion cracking in the spherical tank and the overall heat treatment effect is difficult to guarantee, i.e., when the residual stress of welding cannot be completely eliminated, the welded parts should be subjected to additional heat treatment first, and then the overall heat treatment after welding should be carried out.

[0088] (6) The hydrogen sulfide content of the medium should be strictly controlled.

[0089] (7) If the nominal thickness of the tank is greater than 50 mm and there is a cracking mechanism during operation, the spherical tank shall be opened for inspection one year after it is put into use.

[0090] 3. The special technical requirements for stress corrosion cracking of liquid ammonia are as follows: (1) Spherical tanks are at risk of stress corrosion cracking, so the impact energy index of steel plates should be increased.

[0091] (2) The spherical tank is at risk of stress corrosion cracking, and the ultrasonic testing quality level is ≥ II.

[0092] (3) When the spherical tank is at risk of stress corrosion cracking and the overall heat treatment effect is difficult to guarantee, i.e., when the residual stress of welding cannot be completely eliminated, the welded parts should be subjected to additional heat treatment first, and then the overall heat treatment after welding should be carried out.

[0093] (4) When stress corrosion cracking of liquid ammonia is present, the water content of liquid ammonia is required to be ≥0.2%.

[0094] (5) If the nominal thickness of the spherical tank is greater than 50 mm and there is a cracking mechanism during operation, the spherical tank shall be opened for inspection one year after it is put into use.

[0095] 4. The specific technical requirements regarding mechanical fatigue are as follows: (1) When there is a risk of mechanical fatigue in the spherical tank, increase the impact energy index of the steel plate.

[0096] (2) When there is a risk of mechanical fatigue in the spherical tank, the ultrasonic testing quality level is Class I.

[0097] (3) When there is a risk of mechanical fatigue in the spherical tank, the manhole forging is set to level IV, and other forgings for low temperature are set to level IV.

[0098] (4) When there is a risk of mechanical fatigue in the spherical tank, each steel plate shall be subjected to tensile and V-notch impact tests.

[0099] (5) Hard marking shall not be used when there is a risk of mechanical fatigue in the spherical tank.

[0100] (6) When there is a risk of mechanical fatigue in the spherical tank and the overall heat treatment effect is difficult to guarantee, i.e., when the residual stress of welding cannot be completely eliminated, the welded parts should be subjected to additional heat treatment first, and then the overall heat treatment after welding should be carried out.

[0101] (7) If the nominal thickness of the spherical tank is greater than 50 mm and there is a cracking mechanism during operation, the spherical tank shall be opened for inspection one year after it is put into use.

[0102] 5. The special technical requirements for low-temperature brittle fracture are as follows: (1) For steel plates with a design temperature < -40℃, an additional drop hammer test shall be conducted in accordance with GB / T 6803-2023.

[0103] (2) Low-temperature steel plates (excluding quenched and tempered steel), i.e. steel plates with a design temperature < -20℃, a thickness > 20mm, and an ultrasonic testing quality level ≥ II.

[0104] (3) The welding rods of spherical tanks made of steel with a design temperature of <-20℃ shall be retested in batches for the moisture content of the coating or the diffusible hydrogen content of the deposited metal.

[0105] (4) For spherical tanks made of steel with a design temperature of <-20℃, the pressure-bearing components shall not be marked with hard stamping.

[0106] (5) Spherical tanks made of steel with a design temperature of <-20℃ shall undergo local heat treatment at the manufacturing plant in advance.

[0107] 6. The special technical requirements for reheat cracking are as follows: Materials with a tendency to reheat cracking must undergo non-destructive surface testing after heat treatment.

[0108] Example 1 1. Enter the following information: Medium name: Propylene; Construction location: A certain city; Nominal volume: 3000m³ 3 ; Design service life: 20 years; Analysis and design required: Yes.

[0109] 2. Representative medium: Based on the medium name, the representative medium is determined to be propylene.

[0110] 3. Other design conditions: According to Table 1, the working temperature is the ambient temperature, the working pressure is 2.06MPa, the hydrogen sulfide is 5ppm, the nominal volume of 3000m³ corresponds to an inner diameter of 18000mm according to standard GB / T 17261-2011, and the structural form is a hybrid type with more support columns, namely a 12-support 4-belt hybrid type.

[0111] 4. Environmental parameters: According to the standards GB 50009-2012 and GB 50011-2010 (2016 edition), the environmental parameters corresponding to a certain city include the minimum temperature of -6℃, basic snow pressure of 600Pa, basic wind pressure of 350Pa, and seismic intensity of 7 degrees (0.10g) in the first group.

[0112] 5. Medium characteristics: According to Table 2, the phase of propylene is liquid, the toxicity hazard level is mild, the explosion hazard level is explosive, and the medium is grouped into Group 1.

[0113] 6. Design parameters: The design pressure is 1.05 times the working pressure (1.05 × 2.06), specifically 2.16 MPa. According to Table 3, the minimum design temperature is -20℃ (the lowest temperature in a certain city is -6℃), and the maximum design temperature is 50℃. No insulation is required. The container category is Class III (Group 1 medium, 1.6MPa < design pressure < 10MPa, PV product is greater than 50), and the weld coefficient is 1.0.

[0114] 7. Shell material selection: If Q370R is selected for the spherical tank, the calculated wall thickness is relatively thick (>45mm), and the medium is not likely to cause stress corrosion cracking, so Q490R is recommended as the material.

[0115] 8. Matching materials: Refer to Table 4, matching forgings 08MnNiMoVD, bolts and nuts 35CrMoA / 30CrMoA, welding rod type E6215-N2M1.

[0116] 9. Corrosion allowance: The corrosion rate of this spherical tank is calculated as 0.025 mm / y; the calculated corrosion allowance is ≤1.0 mm, and the corrosion allowance is taken as 1.0 mm.

[0117] 10. Wall thickness calculation: Calculated thickness: 39.51 mm; Liquid level: 14476 mm; Maximum calculated pressure on the spherical shell: 2.225 MPa; Material: Q490R; Temperature: 50℃; Allowable stress: 254 MPa; Design thickness: 40.81mm, with a negative tolerance of 0.3mm for steel thickness; 11. Corrosion allowance: 1mm; Nominal thickness rounded: 42mm.

[0118] 12. Damage Pattern Recognition

[0119] Damage modes were identified according to Table 5, including brittle fracture, ductile fracture, low-temperature brittle fracture, reheat cracking, and atmospheric corrosion (the most basic damage modes: brittle fracture and reheat cracking; during emergency large-scale release of spherical tanks, local low temperatures may occur due to the throttling effect, which may lead to low-temperature brittle fracture; low-temperature brittle fracture should also be considered in water pressure tests during extreme winter weather; high-strength steel spherical tanks are prone to reheat cracking after stress relief heat treatment after welding; atmospheric corrosion may occur in spherical tanks under normal temperature conditions).

[0120] 13. Process Risk Analysis

[0121] Overfilling risk: Strictly manage the filling operation process, determine the filling temperature and corresponding filling coefficient; set up liquid level alarms and interlocks.

[0122] 14. Special technical requirements

[0123] The specific technical requirements for brittle fracture are as follows: (1) Add a set of impact tests with a sample of 1 / 2 plate thickness for steel plates of spherical tanks. Reason: For steel plates used in quenched and tempered state with a thickness > 36 mm, an additional set of impact tests with a sample of 1 / 2 plate thickness can be added.

[0124] (2) The ultrasonic testing quality grade of the steel plate is Grade I. Reason: The steel grade used in the quenched and tempered state has a thickness of >16mm and a quality grade of Grade I.

[0125] (3) The manhole forging is grade III, and other forgings are grade II. Reason: Manhole forgings are grade III by default, and other forgings are grade II by default.

[0126] (4) Before welding, magnetic particle testing should be performed on the gas cutting bevel. Reason: Magnetic particle testing should be performed on the surface of the gas cutting bevel of steel with a standard tensile strength lower limit of ≥540MPa.

[0127] (5) When welding the spherical shell plate, the welding heat input is required to be 35KJ / cm. The reason is that the welding heat input of high-strength steel should not be too large.

[0128] (6) Non-destructive testing shall be carried out after root cleaning. Reason: Low alloy steel with a standard tensile strength lower limit of ≥540MPa shall be subjected to 100% magnetic particle testing in accordance with NB / T 47013.4-2015 or 100% penetrant testing in accordance with NB / T 47013.5-2015 after root cleaning, and the qualified level shall be ≥ Grade I.

[0129] (7) Perform post-heating hydrogen removal treatment. Reason: For spherical shell butt welds with a weld joint thickness > 32 mm and a material standard tensile strength lower limit ≥ 540 MPa, the post-heating temperature is 200℃-250℃ and the post-heating time is 0.5h-1h.

[0130] (8) Non-destructive testing shall be carried out 36 hours after the completion of welding of the spherical tank. Reason: Spherical tanks made of materials with a tendency to delay cracking shall be subjected to non-destructive testing 36 hours after the completion of welding.

[0131] (9) 100% surface non-destructive testing after pressure test of spherical tank. Reason: Welded joints of spherical tanks with standard tensile strength lower limit Rm≥540MPa should be subject to an additional 100% surface testing after pressure test.

[0132] (10) The overall post-weld heat treatment temperature is 570±20℃. At the same time, the welded parts should also be subjected to post-weld heat treatment before the overall heat treatment. The reasons are: the wall thickness of the spherical tank is >32mm, and the overall post-weld heat treatment is required; the spherical tank made of high-strength steel material needs to be subjected to local heat treatment by the manufacturer; the welded parts should simulate the second post-weld heat treatment; the heat treatment temperature is determined according to GB / T 12337-2014.

[0133] The specific technical requirements for reheat cracking are as follows: The inner and outer surfaces of the spherical tank undergo 100% non-destructive testing after heat treatment. The reason is that materials with a tendency to reheat cracking require non-destructive surface testing after heat treatment.

[0134] In Example 1, if it is necessary to change the material, such as changing the shell material to Q370R, as shown in Example 2.

[0135] Example 2 1. Enter the following information: Medium name: Propylene; Construction location: A certain city; Nominal volume: 3000m³ 3 ; Design service life: 20 years; Analysis and design required: Yes.

[0136] 2. Representative medium: Based on the medium name, the representative medium is determined to be propylene.

[0137] 3. Other design conditions: According to Table 1, the working temperature is the ambient temperature, the working pressure is 2.06MPa, the hydrogen sulfide is 5ppm, the nominal volume of 3000m³ corresponds to an inner diameter of 18000mm according to standard GB / T 17261-2011, and the structural form is a hybrid type with more support columns, namely a 12-support 4-belt hybrid type.

[0138] 4. Environmental parameters: According to the standards GB 50009-2012 and GB 50011-2010 (2016 edition), the environmental parameters corresponding to a certain city include the minimum temperature of -6℃, basic snow pressure of 600Pa, basic wind pressure of 350Pa, and seismic intensity of 7 degrees (0.10g) in the first group.

[0139] 5. Medium characteristics: According to Table 2, the phase of propylene is liquid, the toxicity hazard level is mild, the explosion hazard level is explosive, and the medium is grouped into Group 1.

[0140] 6. Design parameters: The design pressure is 1.05 times the working pressure (1.05 × 2.06), specifically 2.16 MPa; referring to Table 3, the minimum design temperature is -20℃ (the lowest temperature in a certain city is -6℃), and the maximum design temperature is 50℃. No insulation is required. The container category is Class III (Group 1 medium, design pressure > 1.6 MPa and < 10 MPa, PV product > 50), and the weld coefficient is 1.0.

[0141] 7. Shell material selection: Q370R is selected for the spherical tank.

[0142] 8. Matching materials: Refer to Table 4, matching forgings 20MnMo, bolts and nuts 35CrMoA / 30CrMoA, welding rod type E5015-N1.

[0143] 9. Corrosion allowance: The corrosion rate of this spherical tank is calculated as 0.025 mm / y; the calculated corrosion allowance is ≤1.0 mm, and the corrosion allowance is taken as 1.0 mm.

[0144] 10. Wall thickness calculation: Calculated thickness: 47.07 mm; Liquid level: 14476 mm; Maximum calculated pressure on the spherical shell: 2.225 MPa; Material: Q370R; Temperature: 50℃; Allowable stress: 213.25 MPa; Design thickness: 48.37mm, with a negative deviation of 0.3mm for steel thickness.

[0145] 11. Corrosion allowance: 1mm; Nominal thickness rounded to: 50mm.

[0146] 12. Damage Pattern Recognition

[0147] Damage modes were identified according to Table 5, including brittle fracture, ductile fracture, low-temperature brittle fracture, and atmospheric corrosion (the most basic damage mode: brittle fracture; when a large amount of water is released from a spherical tank in an emergency, the throttling effect may cause local low temperatures, which may lead to low-temperature brittle fracture; low-temperature brittle fracture should also be considered in water pressure tests during extreme winter weather; atmospheric corrosion may occur in spherical tanks under normal temperature conditions).

[0148] 13. Process Risk Analysis

[0149] Overfilling risk: Strictly manage the filling operation process, determine the filling temperature and corresponding filling coefficient; set up liquid level alarms and interlocks.

[0150] 14. Special technical requirements

[0151] The specific technical requirements for brittle fracture are as follows: (1) The ultrasonic testing quality grade of the steel plate is Grade II. Reason: The thickness of Q370R steel plate is >25mm, and the quality grade is ≥ Grade II.

[0152] (2) The manhole forging is grade III, and other forgings are grade II. Reason: Manhole forgings are grade III by default, and other forgings are grade II by default.

[0153] (3) When welding the spherical shell plate, the welding line energy requirement is 40KJ / cm. The reason is that the welding line energy should not exceed the upper limit of the line energy that has been qualified by the welding process evaluation.

[0154] (4) Perform non-destructive testing after root cleaning. Reason: It is best to perform non-destructive testing after root cleaning.

[0155] (5) Perform post-heating hydrogen removal treatment. Reason: For low alloy steel spherical shell butt welds with a joint thickness > 38 mm, the post-heating temperature is 200℃-250℃ and the post-heating time is 0.5h-1h.

[0156] (6) Non-destructive testing shall be carried out 24 hours after the completion of welding of the spherical tank. Reason: It is assumed that non-destructive testing shall be carried out 24 hours after the completion of welding.

[0157] (7) The overall post-weld heat treatment temperature is 580±20℃. Reason: The wall thickness of the spherical tank is >32mm, so it is recommended to perform overall post-weld heat treatment. The heat treatment temperature is determined according to GB / T 12337-2014.

[0158] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for spherical storage tanks based on damage mode logic chains, characterized in that, Includes the following steps: S1. Determine the design conditions of the spherical tank, including: obtaining the installation location of the spherical tank, the name of the stored medium, the nominal volume of the spherical tank and the design service life, determining the representative medium and its corresponding medium characteristics, determining the working temperature, working pressure, hydrogen sulfide content, inner diameter and structural form, and determining the environmental parameters; S2. Based on the design conditions of the spherical tank, determine the design parameters of the spherical tank, including: the basic parameters of the spherical tank, shell material selection, supporting materials, corrosion allowance and wall thickness; S3. Based on the design conditions and parameters of the spherical tank, identify the damage modes of the spherical tank, including: damage mechanism identification and process risk analysis; S4. Determine the special technical requirements for the spherical tank based on its damage mode; During the design process, dynamic relationships are formed between each step. When a parameter in a previous step changes, subsequent parameters are adjusted accordingly.

2. The spherical storage tank design method based on damage mode logic chain according to claim 1, characterized in that, The representative medium is determined by the name of the stored medium, including liquefied petroleum gas, propane, propylene, n-butane, isobutane, butene, isobutene, pentane, pentene, liquid ammonia, dimethyl ether, ethylene oxide, ethane, ethylene, carbon dioxide, Freon-23, air, natural gas, oxygen, nitrogen, LNG, and hydrogen. The operating temperature, operating pressure, and hydrogen sulfide content are all determined by a representative medium, and the inner diameter and structural form are all determined by the nominal volume of the spherical tank. The environmental parameters are determined by the installation location of the spherical tank, including the minimum temperature at the installation location, the basic snow pressure at the installation location, the basic wind pressure at the installation location, and the seismic intensity at the installation location; The characteristics of the medium are determined by representative media, including phase, degree of toxicity, degree of explosion hazard, and media grouping.

3. The spherical storage tank design method based on damage mode logic chain according to claim 1, characterized in that, In step S2, the basic parameters include design pressure, design temperature, vessel type, weld coefficient, and insulation requirements; When a safety valve is installed in the spherical tank, the design pressure is equal to the set pressure. Furthermore, the set pressure is determined as follows: First, assume the set pressure is 1.05-1.1 times the working pressure, and then calculate the set pressure. When the calculated set pressure is ≥0.18MPa, the set pressure is 1.05-1.1 times the working pressure; when the calculated set pressure is <0.18MPa, the set pressure is >1.1 times the working pressure. When the spherical tank is not equipped with a safety valve, the design pressure is 1.05 times the working pressure; The minimum design temperature is determined by the lowest air temperature and the operating temperature at the installation location of the spherical tank. The container categories include Class I pressure vessels, Class II pressure vessels, and Class III pressure vessels. When the container category is Class I pressure vessel, the weld coefficient is 0.85; when the container category is Class II or Class III pressure vessel, the weld coefficient is 1.

0.

4. The spherical storage tank design method based on damage mode logic chain according to claim 1, characterized in that, In step S2, the step of selecting the shell material is as follows: (1) When the minimum design temperature is ≥-20℃, the default material for the spherical tank is Q370R, and the tank wall thickness is calculated based on the default material. Furthermore, if the calculated tank wall thickness is ≥45mm and the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen and hydrogen, then the tank material is changed to Q490R. If the calculated tank wall thickness is <38mm and the representative medium is liquefied petroleum gas, then the tank material is changed to Q245R or Q345R. (2) When -40℃≤minimum design temperature<-20℃, the default material for the spherical tank is 16MnDR, and the tank wall thickness is calculated based on the default material. Furthermore, if the calculated tank wall thickness is >45mm, and the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen and hydrogen, then the tank material is changed to Q490DRL1. (3) When -50℃≤minimum design temperature<-40℃, the default material for the spherical tank is 15MnNiNbDR, and the tank wall thickness is calculated based on the default material. Furthermore, if the calculated tank wall thickness is >45mm, and the representative medium is one of propylene, oxygen, carbon dioxide, nitrogen and hydrogen, then the tank material is changed to Q490DRL2. (4) When -70℃≤minimum design temperature<-50℃, the material of the spherical tank shall be 09MnNiDR; (5) When -196℃≤minimum design temperature<-70℃, the material of the spherical tank shall be austenitic stainless steel.

5. The spherical storage tank design method based on damage mode logic chain according to claim 1, characterized in that, In step S2, the corrosion allowance = corrosion rate × design life; Among them, when the representative medium is one of liquefied petroleum gas, ethylene, ethane, carbon dioxide and Freon-23, the corrosion rate is 0.075 mm / y; when the representative medium is LNG, the corrosion rate is 0.01 mm / y; and the corrosion rate of other representative media is 0.025 mm / y. When the calculated corrosion allowance is ≤1.0mm, the corrosion allowance shall be taken as 1.0mm; When 1.0mm < calculated corrosion allowance ≤ 1.5mm, the corrosion allowance is taken as 1.5mm; When 1.5mm < calculated corrosion allowance ≤ 2.0mm, the corrosion allowance is taken as 2.0mm; When the calculated corrosion allowance is greater than 2.0 mm, the value is rounded up.

6. The spherical storage tank design method based on damage mode logic chain according to claim 1, characterized in that, In step S3, the damage modes identified based on damage mechanism include ductile fracture, brittle fracture, low-temperature brittle fracture, mechanical fatigue, reheat cracking, liquid ammonia stress corrosion cracking, wet hydrogen sulfide damage, acidic water corrosion, corrosion under the insulation layer, and atmospheric corrosion. The method for process risk analysis is as follows: (1) If the representative medium is in the liquid phase, the spherical tank is at risk of overfilling. The filling temperature and the corresponding filling coefficient need to be determined, and a liquid level alarm and interlock should be set. (2) If the representative medium is in the gas phase, the working pressure of the spherical tank is prone to fluctuation, so a pressure monitoring, alarm and control system should be set up. (3) If the representative medium is liquefied petroleum gas, the spherical tank is at risk of exceeding the hydrogen sulfide content. (4) If the representative medium is oxygen, the spherical tank is at risk of combustion and explosion. Carbon tetrachloride is used to degrease the parts of the inner wall of the spherical tank that come into contact with oxygen. (5) If the representative medium is one of ethylene, ethane, carbon dioxide and Freon-23, the spherical tank is at risk of overpressure. Temperature and pressure alarms, interlocks and circulating cooling processes should be set up.

7. The spherical storage tank design method based on damage mode logic chain according to claim 6, characterized in that, In step S4, the specific technical requirements for brittle fracture are as follows: (1) For spherical tank steel plates with wall thickness > 36 mm after quenching and tempering, an additional set of impact tests shall be conducted at 1 / 2 of the steel plate thickness. (2) For steel plates of spherical tanks with a wall thickness of >50mm that have been normalized or normalized and tempered, an additional set of impact tests shall be conducted at 1 / 2 of the steel plate thickness. (3) For spherical tank steel plates with a wall thickness > 36 mm and a standard tensile strength lower limit ≥ 540 MPa, a drop hammer test shall be conducted; (4) When the thickness of the steel plate of the spherical tank after quenching and tempering is >16mm, the ultrasonic testing quality level is Class I; (5) When the thickness of Q370R steel plate is >25mm, the ultrasonic testing quality level is ≥II; when the thickness of Q345R or Q245R steel plate is >36mm, the ultrasonic testing quality level is ≥II. (6) For spherical tank steel plates that have undergone quenching and tempering heat treatment or have a wall thickness > 60 mm, each steel plate shall be subjected to tensile and V-notch impact tests; (7) Magnetic particle testing was performed on the gas-cut bevel surface of spherical tank steel with a standard tensile strength lower limit value ≥540MPa; (8) Re-inspection of Class IV forgings used in Class III pressure vessels purchased; (9) The welding heat input of spherical tank steel with a standard tensile strength lower limit ≥ 540 MPa is ≤ 35 KJ / cm; (10) Low alloy steel with a standard tensile strength lower limit of ≥540MPa shall be subjected to 100% magnetic particle testing or 100% penetrant testing after root cleaning, and the qualification level shall be ≥ Grade I. (11) For butt welds of spherical tanks with a weld joint thickness > 32 mm and a standard tensile strength lower limit ≥ 540 MPa, the post-heating temperature is 200℃-250℃ and the post-heating time is 0.5h-1.0h; For butt welds of low alloy steel spherical tanks with a weld joint thickness > 38 mm, the post-heating temperature is 200℃-250℃ and the post-heating time is 0.5h-1.0h. (12) Spherical tanks made of steel with a standard tensile strength lower limit of ≥540MPa shall undergo non-destructive testing 36 hours after welding is completed; (13) For spherical tanks with a standard tensile strength lower limit ≥ 540 MPa, the welded joints shall undergo an additional 100% surface inspection after the pressure test; (14) Spherical tanks with a wall thickness > 32 mm and spherical tanks with representative extremely hazardous or highly hazardous media shall undergo post-weld overall heat treatment; if the spherical tank is not subjected to post-weld overall heat treatment on site, the local welded structure shall be subjected to post-weld heat treatment at the manufacturing plant; spherical tanks made of steel with a standard tensile strength lower limit ≥ 540 MPa shall undergo local heat treatment at the manufacturing plant in advance. (15) Spherical tanks made of steel with a standard tensile strength lower limit of ≥540MPa shall be opened for inspection one year after they are put into use.

8. The spherical storage tank design method based on damage mode logic chain according to claim 6, characterized in that, In step S4, the specific technical requirements for the destruction of wet hydrogen sulfide are as follows: (1) When the representative medium is liquefied petroleum gas, there is a risk of hydrogen sulfide exceeding the standard, and when the wall thickness is >36mm, an additional set of impact tests is added, with samples taken at 1 / 2 of the steel plate thickness. (2) When there is a risk of damage from wet hydrogen sulfide in the spherical tank, increase the impact energy index of the steel plate; (3) When there is a wet hydrogen sulfide destruction mechanism and the hydrogen sulfide content is >500ppm, reduce the sulfur and phosphorus content index of the steel plate. (4) The toxicity of the representative medium is extremely or highly hazardous, or the spherical tank is used in a wet hydrogen sulfide environment, and the ultrasonic testing quality level of the steel plate is ≥ Grade II; (5) The spherical tank is at risk of stress corrosion cracking and the overall heat treatment cannot completely eliminate the residual welding stress. The welded parts should be heat treated first and then subjected to overall heat treatment after welding. (6) If the nominal thickness of the spherical tank is greater than 50 mm and there is a cracking mechanism during operation, the spherical tank shall be opened for inspection one year after it is put into use.

9. The spherical storage tank design method based on damage mode logic chain according to claim 6, characterized in that, In step S4, the specific technical requirements for stress corrosion cracking of liquid ammonia are as follows: (1) Improve the impact energy index of steel plates; (2) Ultrasonic testing quality level ≥ Grade II; (3) The welded parts are first heat-treated, and then the overall heat treatment is performed after welding; (4) The water content of liquid ammonia is ≥0.2%; (5) The nominal thickness of the spherical tank is greater than 50 mm. The spherical tank shall be opened for inspection one year after it is put into use.

10. The spherical storage tank design method based on damage mode logic chain according to claim 6, characterized in that, In step S4, the specific technical requirements regarding mechanical fatigue are as follows: (1) Improve the impact energy index of steel plates, set the ultrasonic testing quality level to level I, set the manhole forgings to level IV, set other forgings for low temperature use to level IV, conduct tensile and V-notch impact tests on each steel plate, and do not use hard marking; (2) The welded parts are first heat-treated, and then the overall heat treatment is performed after welding; (3) The nominal thickness of the spherical tank is greater than 50 mm. The spherical tank shall be opened for inspection one year after it is put into use. The specific technical requirements for reheat cracking are: the spherical tank must undergo non-destructive surface testing after heat treatment; In step S4, the specific technical requirements regarding low-temperature brittle fracture are as follows: (1) For steel plates with a design temperature < -40℃, a drop hammer test is performed; (2) For steel plates with a design temperature < -20℃, except for quenched and tempered steel, the thickness of the steel plate is > 20mm, and the ultrasonic testing quality level is ≥ II. (3) For spherical tanks made of steel with a design temperature of <-20℃, the coating moisture content or the diffusible hydrogen content of the weld metal shall be retested in batches; (4) For spherical tanks made of steel with a design temperature of <-20℃, pressure-bearing components shall not be marked with hard stamping; (5) Spherical tanks made of steel with a design temperature of <-20℃ shall undergo local heat treatment at the manufacturing plant in advance.

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