Issues related to the negative deviation of sw6-2011 steel plates

This post was last edited by jizhanwei22 on 2016-6-16 10:33. Could the known parameters be listed? What kind of steel plate are you asking about? Carbon steel or stainless steel? You can only guess when replying! ! ! 1. What standard is GB706? ? ? ? Go and take a good look; don’t get it mixed up! ! ! (That is for section steel.) 2. Under normal circumstances, carbon steel and alloy steel plates used for pressure vessels have a fixed negative deviation of 0.3 mm (Grade B). Special cases (requiring even higher precision) need to be agreed upon through negotiation between the supplier and the buyer. Among the thicknesses of carbon steel plates for pressure vessels specified in GB150, there are no plates with a thickness of less than 3 mm. So what you’re asking about is stainless steel plates, right? 3. For the negative deviation in the thickness of stainless steel plates used for pressure vessels, ordinary precision is generally adopted. According to the various nominal widths of plates specified in GB24511, a negative deviation of 0.28 is allowed for stainless steel plates with a thickness of less than 3 mm. In fact, if you adjust the thickness and nominal width (i.e., the length of the cylinder), the negative deviation might even reach 0.22, 0.25, or 0.29.

First of all, thank you to the thread owner for answering patiently! I use 316L or 304 stainless steel. According to GB/T 706-2006, the steel plates used for pressure vessels are specified as belonging to category (B), with a fixed negative deviation of 0.3. However, when a nominal thickness of 3 is used, the calculated negative deviation for the steel plate is 0.28 (for materials of 316L or 304). Indeed, by entering the nominal thickness as you suggested, a value of 0.25 appears. When 3.001 is entered, the negative deviation of the steel plate becomes 0.3, and the calculation result is still determined based on the nominal thickness of 3, rather than 3.001. Thus, for calculations using the same parameters, there are two scenarios: In the first scenario, the nominal thickness is set to 3, and the negative deviation for the steel plate is calculated as 0.28; in the second scenario, the nominal thickness is indicated as 3, but the actual input value is slightly greater than 3, with the negative deviation for the steel plate being calculated as 0.3. I have some doubts; I’ll take another look at GB24511 you mentioned. Please point out any inaccuracies in the above content! Thank you!

The nominal thickness cannot be 3.001; please check GB150 carefully. The nominal thickness is the rounded value; how can there be decimals? ? In my opinion, those in the tech field can delve into complex details, but not into nonsense. You’re entering numbers without following the rules – how do you expect to get correct results? Additionally, the title of GB706-2008 is \"Hot-rolled Section Steel\"

Sorry, my words were a bit rough. Newcomers should read more books; let’s encourage each other.

Mm-hmm, 3.001 is just an example; it means that for nominal thicknesses greater than 3, a negative deviation of 0.3 is applied to the steel plate thickness. If it’s convenient, you can try it with software; it seems like you didn’t understand what I meant. Thank you for your reply

The issue with your question lies in the selection criteria used; the value of 0.3 refers to GB713 \"Steel Plates for Boilers and Pressure Vessels\", which applies to carbon steel and low-alloy steel. The material you have chosen, however, is stainless steel (304 and 316L), which belongs to the category of high-alloy steel, and the relevant standards for such materials are GB24511. You should check this standard. So the program was developed in accordance with the specifications, and there are no issues. You can replace the material with carbon steels and low-alloy steels such as Q345R or Q370R; regardless of the thickness, the negative deviation will be 0.3. I hope I explained it clearly; if it’s useful to you, I’d appreciate some small reward.

Article 4.3.6.1 of GB150-2011 \"Pressure Vessels\" specifies explicitly that the negative deviation in the thickness of plates or pipes shall be in accordance with the provisions of the material standards. It is the \"material standards\" that apply here; therefore, for carbon steel and low-alloy steel, standards such as GB713 apply, while for stainless steel, standards such as GB24511 apply. GB706 is not directly applicable, as it is a reference standard for material standards. Check how the specific standards for various materials are defined.

Thank you to the forum owner for the answer! ! ! ! !