For UT testing of steel plates, what should be the acceptable grade?
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Classified by capacity, according to GB150, steel plates are subjected to UT testing under certain conditions. Taking the provisions of GB150.2-2011 as an example, see the screenshot. NB/T 47013 did issue a revision in 2018; a comparison of the content before and after this revision is shown below. Well, with this revision, many designers had their qualification levels raised, as illustrated in the diagram below. So, raising these qualification levels – isn’t that right? (I guess it’s fair to say that the requirements were increased, right?) ) From a purely standard perspective, is it appropriate or not? I remember during a training session, the expert instructor said something to the effect that after the standards were established, many companies reported that the requirements were too strict and impossible to meet. Based on this, amendments were made to lower the quality standards. But after those amendments, the designers increased the standards again; so it’s as if nothing had changed at all But I only remember something like this: when discussing this issue, if you have no evidence to back up your arguments when talking with others, how can you dare to set the pass standard based on the original criteria? I searched repeatedly, went through everything carefully, read the instructions related to the large-capacity repair orders, and looked for the draft documents for soliciting opinions regarding version 150 as well as those related to design analysis. Although the level of these draft documents remained unchanged (consistent with the level specified in GB150-2011), they still cannot be used as a basis. Finally, I found what could be considered an authoritative explanation. Indeed, it was mentioned in the explanatory notes for the six-in-one standard, and there were also relevant responses in the consultation messages sent to the State Administration for Market Regulation. I’m posting this here as a record, so that I won’t forget to refer to it again and have to search around unnecessarily; it’s shared here for those who are interested
According to the provisions of GB150.2-2011 \"Pressure Vessels – Part 2: Materials\", the acceptable grades for ultrasonic testing of steel plates are generally divided into Grade I, Grade II, and Grade III. GB150.2-2011 specifies requirements for ultrasonic testing levels under different steel plate thicknesses and operating conditions. The specific level should be determined based on actual applications and design requirements. Generally, grade I represents the highest quality requirements, while grade III is relatively lower. In practical operations, the acceptable level must be determined based on the specific requirements of the design documents and relevant standards. For specific engineering projects or particular user requirements, it may also be necessary to refer to project specifications or contract terms to determine the specific compliance level. .
It’s been saved. Previously, one expert said that the standard level needed to be raised; a few years later, another expert suggested using a value of 150. In essence, the reason for the change in the ultrasonic testing standards is that, with the adoption of NB/T47013, the requirements for ultrasonic testing of steel plates became too strict, which caused dissatisfaction among everyone
This post was last edited by wanlirn on 2023-11-24 at 13:56. When technical standards conflict with product standards, an announcement will definitely be issued to facilitate coordination. Blindly and mechanically applying standards is a common problem among designers these days
Six-in-one, I usually call it 2058 something; P