The material selection issue for a Class 3 container
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For type three pressure vessels using natural gas as the medium, with a minimum temperature of 10°C and a minimum ambient temperature of -43°C, a design pressure of 12 MPa, and the customer requesting the use of 16MnDR material; the shell dimensions being Φ325*18 – is it acceptable to use 16Mn GB6479 steel pipes in this case? Thank you.
First, it is necessary to clarify the difference between the two: 16MDR is used when the temperature is below -20 degrees. If the temperature is at room temperature, the difference is not significant. Since the minimum ambient temperature is -43, 16MDR should be used at this temperature
Users still emphasized the effect of low temperatures in the environment. So if you choose tubing to make the shell, you should also ensure that the tubing has good low-temperature performance; otherwise, it’s better to design it for low temperatures and low stress in order to avoid issues associated with low temperatures.
I remember that the operating temperature for 16MnDR is not lower than -40 degrees. 16Mn pipes can be used in combination with 16MnDR sheets; 16MnDR is used for manufacturing equipment while 16Mn is used for making connectors. For the equipment you mentioned, considering environmental temperatures, other low-temperature steels should be used
It depends on whether it is a storage container; if it is not a storage container, the minimum ambient temperature need not be considered – either option is acceptable. If it is a storage container, the minimum operating temperature for both 16MnDR and 16Mn is -40; neither meets the requirement for the minimum ambient temperature, unless low-temperature and low-stress conditions can be satisfied.
It’s for the top fifth floor! No further explanation needed! The reasons are sufficient! If the owner insists on using 16MnDR, they should submit a written report to rule out any responsibility on their part, thereby protecting both themselves and the company! But if the materials you use differ from those specified by the owner, you too should submit a written report explaining the reasons!
According to C1.5 in Appendix C of National Standard 150, if a compressed component is used under \"low-temperature and low-stress conditions\", and the temperature rises by 50 degrees resulting in a value above -20, it is not necessary to use 16MnDR. Is that correct? This post was last edited by andreachen on 2009-4-7 11:22]
Natural gas is not suitable for low temperatures and low stresses, as its pressure does not change much within this temperature range. If it is a storage container, an insulating layer can be considered for use outdoors to prevent low temperatures in the environment
I agree with the view from floor 8. Natural gas does not belong to low-temperature liquefied gases, and low-temperature bottom stress conditions are generally not taken into consideration； For an ambient temperature of -43°C, insulation should be considered, and the thickness of the insulation shall be determined by the process department.
It must be clearly stated whether the minimum operating (metal) temperature is determined by the minimum ambient temperature. Based on the poster’s description, the lowest temperature is 10 degrees Celsius, so it shouldn’t be a low-temperature container.
Suggestions for the poster: 1. Find out whether -43°C refers to the extreme lowest temperature or the average lowest temperature per month； 2. Determine whether the equipment is a process device or a storage device ； 3. Determine whether there are measures in place to ensure the medium temperature. GB150 specifies that when determining the minimum design metal temperature, full consideration should be given to the impact of low-temperature conditions in the atmospheric environment on the temperature of the vessel shell during operation. The low-temperature condition of the atmospheric environment refers to the lowest value of the monthly average minimum temperatures over the years. Therefore, if the monthly average temperature is -43°C and there are no reliable measures to ensure the temperature of the medium, using 16MnDR is also unreliable; it is recommended to use 07MnNiDR instead ； If there are reliable measures to ensure that the metal temperature is not affected by the ambient temperature, 16MnR can be used ； If 16MnDR is chosen, the average monthly minimum temperature is likely to be between -20°C and -40°C, and the medium temperature cannot be guaranteed with certainty.