Questions regarding “pressure testing – stress verification”
Thread Content
The standards specify the conditions that the cylinder stress σT must satisfy; the calculation parameters involve the yield strength of the material at the test temperature. However, for high-alloy steel plates, this mechanical property of the material is not provided in Table 4-1 of GB150, which lists the allowable stresses for steel plates. In such cases, what conditions must the cylinder stress meet under the test pressure?
The fact that it’s not listed at 150 doesn’t mean this data is not available; one can consult relevant materials, as this data is present in many reference books
This data is available in GB150.
I checked the relevant standard for steel plates, GB/T4237 for hot-rolled stainless steel plates and strips, and there was nothing there either: dizzy:
Please indicate the source, which chapter or which figure?
As stated in the stress analysis section of JB4732, and in accordance with the requirements of this standard, when ordering steel plates, a guarantee for the yield strength at room temperature should be provided; the user must specify this requirement when placing orders with the steel manufacturer. Additionally, the yield strength at room temperature can be found in the corresponding standards for stainless steel materials, such as GB4237 for steel plates and JB4728 for forgings. GB150 does not specify the yield strength at room temperature. In my opinion, there are two reasons for this; whether these reasons are correct is open to discussion. The first is that stainless steel materials do not have a distinct yield point, and it is necessary to specify this requirement when placing an order. 2 refers to the phenomenon of \"cold working hardening\" that occurs after stainless steel is processed; in this case, the yield strength of the material increases. Therefore, the yield strength at room temperature is not a fixed value, as it depends on the processing method used.
I think what you say makes a lot of sense, but I still haven’t been able to find its yield strength—0Cr18Ni12Mo2Ti:dizzy:
JB4732, Table 6-2: The room temperature yield strength of 0Cr18Ni12Mo2Ti steel plates is 205 MPa
Stainless steel should use a yield strength of 0.2%, precisely because it does not have a distinct yield limit.
Thank you, I understand that. However, GB150 only requires stress verification prior to the pressure test; it seems there are no regulations or suggestions for what to do in cases where the stress verification fails
:Funk: Bro, do we really need to set rules for this? If something doesn’t meet the standards, of course we need to find a way to make it meet them. As for what method to use, as long as it meets the required standards, whatever you do will work; but generally, people seem to opt for increasing the wall thickness.