Gentlemen, for a tower 18 meters high with a pressure of 0.005, containing hazardous materials at that height, is it necessary to perform 100% radiographic inspection of the AB welds of this equipment?

If the content of highly hazardous media is very low, such as 2%, does this tower still require 100% radiographic inspection and heat treatment for both Class A and Class B components?

Let’s check the design requirements; basically, that’s the case – to reduce one’s own mistakes

It depends on how the process engineers who set the criteria make their judgment; if, although the concentration of the medium is low, it is classified as an extremely or highly hazardous medium based on a comprehensive assessment, then 100% non-destructive testing is still required

Since it is a high-risk substance, even if it’s only 2%, it’s best to conduct 100% testing. If I were a designer, unless there are clear design specifications to follow, I would definitely choose 100% testing. Because of this possibility – for example, a concentration of 0.1% in the air can be fatal. To reduce the number of inspections, one still needs to turn to the designers; but from a designer’s perspective, unless there are clear standards and specifications, they certainly won’t lower the inspection requirements.

On one hand, it’s human lives + imprisonment； On one hand, there is a savings on inspection costs, but that money doesn’t end up in one’s own pocket; a sensible designer will make the right choice.

Child! Looking at the design drawings – how is it that no one in the manufacturing unit knows how to read them? When you go back, you need to study the laws and regulations, technical specifications, standards, and instruction manuals carefully; you can’t just do whatever your supervisor tells you to do. It is necessary to indicate on the drawing the media that pose a high hazard; that way it’s clear. If it is a mixed substance, this needs to be determined based on standards; **there are relevant standards.

According to NB/T 47041-2014, the design pressure of towers manufactured using tower-type containers must be greater than or equal to 0.1 MPa; in accordance with clause 10.3.1 of GB/T150.4, 100% non-destructive testing is required. I believe that according to the criteria specified in HG 20660 regarding stripes, a content level below half of the lethal dose can be considered extremely low, allowing for consideration of downgrading the toxicity category.

Since the properties of the medium indicate a high level of hazard, there’s no need to consider its concentration – 100% inspection is required.

In HG 20660, it is not stated that a content level below half of the lethal dose constitutes an extremely low amount, which would allow for consideration of downgrading the toxicity category. ” Personally, it is recommended to follow the design specifications, with the design being determined in accordance with the stricter of HG 20660-2000 and HG/T 20660-2017. To be precise, HG 20660-2000 must be followed, as it is mandatory; HG/T 20660-2017 is more scientific. Although the 2017 version replaces the 2000 version, it cannot replace it legally; replacement is only possible once new regulations are introduced, but unfortunately this aspect has not been taken into account. The standard has not been abolished; it has only been replaced. Implementing the new version is more scientific, and there is nothing wrong with using the old version as well. However, it is essential to distinguish between mandatory and recommended practices outlined in the standards. When implementing HG/T 20660-2017, it is necessary to also comply with HG 20660-2000.

Regarding mixed media, if none of the components in the mixture are listed in HG 20660-2000, their classification should be determined in accordance with Appendix A of HG 20660-2000; as for GBZ 230-2010, I can only say that it can be used as a reference or ignored. Even according to HG/T 20660-2017, the mixed medium is determined based on the component with the highest toxicity in the mixture. Therefore, the classification of toxicity levels is carried out in accordance with HG 20660-2000.