Can 4mm Q235-B be used for pressure vessel shells?
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This post was last edited by spirit_hghc on 2011-9-21 at 11:24. According to GB150-1998, the corrosion margin should be 1 mm. Can Q235-B with a thickness of 4 mm be used for pressure vessel shells? Because GB150 specifies minimum thickness requirements; for carbon steel, the thickness after shaping must be no less than 3 mm, excluding the corrosion allowance. If a 4mm thick plate is purchased, it usually has a negative deviation, which means it does not meet the standards. If you want to use the 4mm specification, you must specify a requirement for no negative deviation at the time of purchase, is that correct? Is 5mm Q235-B easy to purchase? Should I just use 6mm? In the aforementioned cases, for example, for containers of DN500x500, is 6mm steel plate also used? I see that some drawings use 4mm directly; how do they manage to meet the requirements of GB150?
It is recommended to purchase 6mm ones for safety reasons
It is recommended to use 6mm; 5mm refers to the common thickness of stainless steel plates, as specified in HG20580-20585-1998 P35
As far as I know, Q235B is no longer recommended for use in pressure vessel shells; materials such as Q245R and Q345R are generally used instead. Check GB713.
1. Q235-B can be used for pressure vessel shells in accordance with GB150-98, but there are certain conditions for its use. 2. “GB150 specifies minimum thickness requirements; excluding the corrosion allowance, the thickness of carbon steel after shaping should be no less than 3 mm.” This applies to conventional vessel manufacturing processes, and it is also difficult to obtain sheets with thinner thicknesses. 3. “For example, a container with a volume of 0.1 m3” – containers with too small a volume may not be considered as ‘pressure vessels’ under GB150.
Although 5mm is a common thickness for stainless steel, carbon steel should also have such specifications; it’s just not clear whether they are available for purchase
Feel free to reply; I have changed the content. The main question is whether 4mm can be used or how it can be used
According to the standards, it seems that the 3mm requirement is not met; this requirement exists due to considerations related to welding processes. Personally, I think 4mm should be sufficient for welding as well. If the corrosion margin is 3mm, can’t we use material with a thickness of 6mm?
Theoretically, it can be used as long as the relevant constraints are met.
GB150-2010 has removed Q235 from the materials allowed for use in pressure vessels
It is recommended to use Q245R steel plates with a thickness of 6 mm. 1. Q235B can no longer be used to manufacture pressure-bearing components of pressure vessels; for containers handling general media, Q245R is used. 2. Even if a steel plate with a thickness of 4 mm meets the strength requirements, considering 3 mm (the minimum required thickness) + 1 mm (corrosion allowance) + the negative deviation in thickness of the steel plate (usually 0.3 mm), the total thickness becomes greater than 4 mm; rounding up gives 5 mm. However, since 5 mm is an odd number and it is difficult to find steel plates of that thickness, it is recommended to use 6 mm.