Container wall thickness issue

Could it be that the values for factors such as negative deviation, corrosion allowance, and safety margin are different?

The same; the main design parameters have been verified

Yes, in many cases it’s the user who decides on the thickness; I don’t understand why such a high value is chosen

In the design of chemical processing equipment, the nominal thickness of the cylinder and heads is usually chosen to be relatively large. This is mainly because various factors that may arise during actual operation need to be taken into account: 1. **Corrosion allowance**: Equipment may be subject to corrosion over time, especially in the chemical industry, where the chemicals used can be highly corrosive to the materials of the equipment. Using a thicker wall thickness can extend the service life of the equipment. 2. **Negative deviation**: There may be a negative deviation in the material thickness during the production process, meaning the actual thickness is smaller than the standard value. A larger nominal thickness can compensate for this deviation, ensuring that the actual performance of the device meets the design requirements. 3. **Temperature and pressure fluctuations**: Under actual operating conditions, the equipment may encounter temperature and pressure fluctuations that exceed those assumed in the calculations. Increasing the wall thickness can provide additional safety. 4. **Structural stability and mechanical strength**: Thicker walls can enhance the overall structural stability and load-bearing capacity of the equipment, especially for large-scale devices or those subjected to periodic changes in load such as pressure or temperature. 5. **Manufacturing and processing tolerances**: During the equipment manufacturing process, processing errors are also inevitable. A pre-set thicker wall thickness helps ensure that the final product meets the design specifications. Although theoretical calculations suggest that the minimum thickness required for the device may be relatively small, practical considerations lead to a nominal thickness that is usually set to be larger. While this does increase material costs, in the long run it can reduce maintenance costs and potential risks, as well as improve the reliability and safety of the equipment – which is particularly important in the chemical industry. Safety margins must be ensured during design, and relevant safety and design standards must be complied with. .

In the design of chemical processing equipment, the wall thicknesses of the cylinders and heads are usually greater than the thicknesses calculated based on theoretical formulas. The main reasons for this are as follows: 1. **Safety factor**: A high safety factor is taken into account during design to ensure that the equipment can operate safely even under extreme conditions. 2. **Corrosion allowance**: Chemical processing equipment often handles corrosive substances, and long-term use can lead to thinning of the equipment walls. Increasing the wall thickness can extend the service life of the equipment. 3. **Manufacturing error**: During the manufacturing process, there may be variations in the thickness of the material. An increase in nominal thickness ensures that even in the event of a negative deviation, the actual thickness of the device will still meet the strength requirements. 4. **Mechanical machining allowance**: During equipment manufacturing or subsequent maintenance, mechanical processing (such as grinding, cutting, etc.) may be required; increasing the thickness appropriately ensures there is sufficient machining allowance. 5. **Design standards and regulatory requirements**: Depending on the regulations and industry standards of different **regions, it is sometimes necessary to determine wall thicknesses in accordance with certain standards, which take into account various safety and operational factors. Although the nominal thickness shown on the drawings may seem to increase costs, this design is intended to ensure the safe, reliable, and long-term stable operation of the equipment. Following these design principles can reduce the risk of accidents and potential future maintenance costs. .

The following are all my guesses. The price of a device is related to its quality, as well as to the ease with which it can be reinforced after drilling holes. Another factor is diameter: when the thickness is relatively low, the cylinder won’t collapse when placed in a horizontal position. In your example, with such large holes in the cylinder, it becomes difficult to manufacture it when the wall thickness is thin.

Could it be a problem with the design institute, aimed at preventing accidents in case something goes wrong? Also, there seems to be a limit regarding the wall thickness specified in the design; the payment amount changes depending on whether the wall thickness exceeds that limit. This is just information for those who are not familiar with this topic

The shell has minimum thickness requirements; compressed components that do not meet these minimum thickness requirements must also take into account requirements such as reinforcement through openings

Generally, customers cannot provide values for loads such as bearing loads and dynamic loads; perhaps the designers increased the back wall thickness after taking all factors into consideration