Is radiographic testing required for the inner coil?

Generally, mixing equipment does not operate at high pressure, nor are the coil diameters large. In our case, unless the drawings specify the use of RT, we use PT.

This post was last edited by ylx0611 on 2012-3-29 at 10:30. Our understanding is that the inner coil can be regarded as a heat exchange tube; in that case, a 10% RT sampling inspection is required, with no fewer than 1 sample to be inspected, and it must meet Grade III standards. Additionally, a separate hydrostatic test is necessary.

Standard specifications do not require it, unless a serious accident occurs when the two media are mixed

I’ve encountered this situation: the number of internal coil connectors is generally not very high. For a total length of 120M, dividing that by 12 means only 10 sheets are needed (for 100% inspection); for random sampling, 2 sheets might be sufficient. If the coil is damaged and the heat transfer medium leaks, it could cause the medium inside the tank to catch fire or lead to a sharp increase in pressure. For example, if the coil contains heat transfer oil, mixing it with the medium inside the tank could trigger a reaction. In such cases, I think designers should be cautious in order to prevent accidents. Additionally, repairing a damaged internal coil is not easy, as there is limited space inside the equipment, with components stacked on top of each other and no space for welding. Moreover, if it’s a closed-reactor tank without flanges, repairing a damaged coil requires significant effort, including removing the head——which brings up another problem: how to reattach the head to the tank body after removal, as well as how to level the stirrer attached to the upper head. I’m not sure if what I’m saying is correct; it’s just my attempt to stimulate further discussion

I agree with the view above; however, sampling is not based on length in meters, but rather 10% of the welding joints are sampled. In fact, the number of samples required is quite substantial, especially in the case of tube bundles (which have many elbows)

I know the number of joints isn’t calculated based on meters; it’s just an example – for a total length of 120, with individual pipes each 12 meters long, this is how I estimate the total number of joints

First, determine whether it falls under the category of pressure vessels; if so, non-destructive testing is recommended, and depending on the medium, either partial or 100% radiographic testing should be carried out； If it is not a pressure vessel, the key factor is to determine whether the medium inside the tank permits leakage of the medium within the coil; if leakage is not allowed, 100% inspection is necessary. If leakage is permitted, then radiographic inspection is not essential. For coils at atmospheric pressure, we generally conduct hydraulic pressure tests and airtightness tests, but no radiographic testing is performed. However, leaks in the coiled tube are very troublesome; it’s generally best to avoid any leaks. It depends on how you detect and avoid leaks.

Thank you all for your answers. It depends on the situation; you need to figure it out for yourself. :)