Regarding three types of pressure vessels

What was said upstairs is correct; for the equipment designed under certificate A1, many components lack calculated models, which is really troublesome. In my opinion, it is essential to learn the fundamentals of mechanics and materials well. Additionally, SW6 also needs to be used proficiently.

However, most ordinary A1 devices still have computational models for their design. If it’s only the strength that needs to be calculated, determining the structure isn’t much different from that of medium- and low-pressure devices. The only complication is that in some cases it’s necessary to develop technical specifications for the device

The three categories are merely a matter of classification; medium and low-pressure vessels can also be classified as category three. For ordinary design firms, it is sufficient to master conventional design methods. Analysis design: over 80% of design firms do not need it

The classification of container types can be used as a reference. For the design of these three types of containers, there are requirements regarding the materials to be used (which need to be rechecked before use), as well as criteria for welding joint quality (related to the proportion of non-destructive testing). There are also requirements regarding the grade of forgings to be used in the materials. When dealing with media that are extremely or highly hazardous, longitudinal welding joints of class A are required. Welding test pieces must be prepared for each unit manufactured; if heat treatment is necessary, it must be carried out in accordance with the relevant regulatory requirements. Due to my limited expertise, please feel free to point out any mistakes – thank you!

Class 3 pressure vessels can also be designed using conventional methods; analytical design is only required when fatigue is a concern. :)

I’m sending you a summary of the technical requirements for Class 3 pressure vessels for reference only. These are highly toxic, hazardous (when in contact with water), and highly corrosive media; such vessels fall under Class 3 pressure vessels. The technical requirements specify that 1. the steel plates used to manufacture Class 3 pressure vessels must be re-inspected, with the inspection including at least an examination of the surface quality and material markings of each plate； Recheck the chemical composition of the steel plate per furnace ； Verify the mechanical properties and cold bending properties of the steel plate in accordance with the approval (do not specify for stainless steel) ； When the steel mill does not provide a certificate of ultrasonic testing for the steel plates, each plate must be subjected to ultrasonic testing (in general, this applies to highly toxic and hazardous media; liquefied petroleum gas contains significant amounts of hydrogen sulfide; the operating pressure is high; various standards require additional testing; this is also necessary for mobile pressure vessels). The required quality level, according to JB/T4730.3--2005, must be at least UT--II grade. The forgings are required to be of grade III, and re-inspection shall be carried out in accordance with Article 25, Paragraph 3 of the Relevant Standards. They must meet the requirements of JB4726-2000 \"Forgings of Carbon Steel and Low-Alloy Steel for Pressure Vessels\" or JB4727-2000 \"Forgings of Low-Alloy Steel for Cryogenic Pressure Vessels\" and JB4728-2000 \"Forgings of Stainless Steel for Pressure Vessels\". For steel plates used in vessels handling extremely toxic and hazardous substances, a V-notch Charpy impact test at 0°C is required, with the impact energy to reach 31 J. 2. The welded joints of nozzles (with a nominal diameter of less than 250 mm) and long-neck flanges shall be subjected to magnetic particle testing (penetrant testing for stainless steel) on their surfaces; the acceptable level is specified as MT-Ⅰ in accordance with JB/T4730.4 (magnetic particle testing is preferred for carbon steel, while penetrant testing per JB/T4730.5 is applicable to stainless steel, with the level being PT-I). 3. Welding test plates shall be prepared for the products, and tests shall be conducted on the properties of the weld metal and the heat-affected zone; the specific procedures shall follow JB4744-2000 \"Testing of Mechanical Properties of Welding Test Plates for Steel Pressure Vessels\". 4. (When the structure cannot ensure that water can be completely removed after a hydrostatic test,) after the equipment is manufactured, an air pressure test and a leak-tightness test shall be conducted. The gas to be used should be dry and clean compressed air with a dew point of below -40°C and a temperature of not lower than 15°C. (Nitrogen or other inert gases may be used if required.) 5. After the equipment is fabricated, overall heat treatment must be carried out to eliminate welding stresses. 6. (For pressure vessels containing flammable materials or highly toxic, hazardous, or poisonous substances, when safety valves are installed,) a conduit should be installed at the outlet of the safety valve or rupture disc to direct the discharged material to a safe location where it can be properly handled; it must not be released directly into the atmosphere. Several additional points that need to be considered: 7. The welding joints between the piping and the vessel shell should be of the fully penetrative type. 8. Welded joints of types A and B shall undergo 100% radiographic inspection, with the acceptance standard being JB/T4730.2 RT-Ⅱ. (Including butt joints of high-diameter flanges and pipes with a diameter of 250 millimeters or more; those with a diameter less than 250 millimeters are to be treated in accordance with item 2 above.) 9. After the equipment is manufactured, in compliance with JB/T4711 standards, the outer surface of the carbon steel shall be descaled to Sa1.5 grade, and two coats of alkyd (or high-temperature resistant) primer shall be applied, along with one coat of topcoat—if required). 10. Once the equipment has been manufactured, remove any dirt or oil from it, purge it thoroughly, and after it is completely dried, seal it up. Heat exchange equipment: 11. (The heat exchange tubes should extend 5 mm beyond the tube sheet.) The welding of the heat exchange tubes to the tube sheet should be carried out using a welding process such that the HB hardness does not exceed 185. 12. Expansion jointing and welding are used between the tube sheet and tubes.

Thank you all. Our company is going to use three types of containers. I’ve only been working with containers for a short time, so I want to catch up on the relevant knowledge first

There is no fundamental difference in the design of Class 3 pressure vessels compared to those of Classes 1 and 2; it is merely the case that Class 3 pressure vessels have higher manufacturing requirements. Designing pressure vessels requires a grasp of basic knowledge in mechanics, materials, welding, heat treatment, etc., as well as familiarity with relevant regulations and standards. The National Technical Committee for Standardization of Boilers and Pressure Vessels has set clear requirements regarding the basic knowledge that pressure vessel design reviewers must possess; these can be found for reference.