Can Q345B be used to manufacture containers and storage tanks?
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The equipment includes atmospheric pressure vessels, a 1500-cubic-meter storage tank, and several pressure vessels (with moderate pressure and temperature requirements; the working medium is not demanding, and these vessels are not classified as such; they are suitable for GB150 standards but are not subject to vessel regulation requirements). The material specified for the atmospheric pressure vessels and the 1500-cubic-meter storage tank is Q235B, while the material for the several pressure vessels is Q345R. Now the customer has Q345B plates and wants to use these plates to manufacture the aforementioned equipment. However, the design institute disagreed, arguing that in the material sections of GB150, NB/T47003.1, and GB50341, the Q345B material is not listed. Materials that are not included in the standards shall not be used. Customer’s comment: Since GB150, NB/T47003.1, and GB50341 all allow the use of Q235B, why can’t Q345B be used? They are all common structural steels. After discussion, the design institute agreed that for atmospheric-pressure vessels and 1,500-cubic-meter storage tanks specified in NB/T47003.1 and GB50341, Q345B could be used, but it did not approve its use for pressure vessels. Customer’s comment: From a standard perspective, the mechanical properties and chemical composition of Q345R and Q345B are almost identical. Why can’t it be used? Design institute: Then nothing will be changed; everything will be done according to the original drawings. What do you all think?
I really haven’t seen Q345B used for pressure vessels. We generally use it on pipes subject to erosion. It really has not been used on the pressure-bearing components of pressure vessels.
I also think pressure vessels can’t be used. But after checking the standards for Q345B material, the sulfur and phosphorus contents, impact energy, and so on, it seems that everything meets the specified requirements. Do you think Q345B is suitable for atmospheric pressure vessels and storage tanks?
Of course they are different; Q235 is carbon steel, while Q345 is alloy steel, so their applications naturally differ. Carbon steel possesses good plasticity and toughness, is easy to shape and weld, and is sufficient as steel plate for atmospheric pressure storage tanks. Alloy steel, due to the addition of trace alloying elements, possesses high strength and toughness, as well as good formability and weldability, making it suitable for the manufacture of bridges, steel structures, pressure vessels, and more. Therefore, Q235 is sufficient for ordinary atmospheric-pressure storage tanks; there is no need to use Q345. Of course, if the owner has the means, I personally think it’s completely fine to use Q345. However, as for the difference between Q345R and Q345B later on: 1. Q345B: is a low-carbon alloy steel (c
If standards are followed strictly, Q345B cannot be used； If it is slightly looser, containers other than those specified in GB150 are allowed to be used ； Design institutes are also afraid of taking risks; P
The client had some Q345B material left over from previous projects. I want to use this pile of materials this time. Additionally, the owner said that many devices were previously manufactured using Q345B, and those devices are still in use today; so there’s no need to worry – we can proceed with confidence!
The owner said that many devices were previously manufactured using Q345B, and those devices are still in use today; so there’s no need to worry – we can proceed with confidence! It is said that there used to be some kind of 3-stainless steel, or boiling steel, which were both used in pressure vessels; Q345B can be used in pressure vessels without any problem.
So the final compromise reached by the design institute is acceptable: it’s fine to use Q345B for atmospheric pressure vessels, but it’s better to use Q345R for pressure vessels – Q345B should not be used. Nothing seems to be wrong for now, but who knows when it might explode? The designers can’t avoid taking responsibility, and they certainly don’t want to bear the blame.
The design institute initially agreed that Q345B could be used for everything other than pressure vessels. The owner insists on normal pressure, and Q345B is used for both storage tanks and pressure vessels. Now the design institute refuses to agree and insists that everything be done exactly according to the original drawings.
The design institute did the right thing – when a problem arises, they first check the drawings； Try not to do things that exceed the standard ；
That’s how it works. But now the owners have their own interests at stake, and they say that the standards are only recommended ones; there is no rule prohibiting the use of Q345B. Talk to the standards and the owners – there’s no way to control them!