Issues regarding the inspection of coiled tubes
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The implementation of the Greater Capacity Regulations has resolved issues of this type associated with coiled tubes, but I still have many questions. For example, there is a VCM storage tank, which is a device of this type; 45 coils of tubing with specifications of 32*4 are wrapped around its exterior, and cold water is used inside these coils to cool the medium. For this coil, since its diameter is less than 150 mm, it certainly does not fall into that category; but should the welding joint coefficient for the seam joining the coils be taken as 1 or 0.85? We carried out welding using TIG welding; it is a fully penetrative weld structure. However, we are not sure how to handle the inspection methods and requirements for the coiled tubes. If the weld coefficient is set to 1, then 100% RT testing is required; if it is set to 0.85, partial inspection is necessary. However, with a cooling water pressure of 0.3 MPa, I think it is sufficient to conduct a hydrostatic test without additional inspections. But in my drawings, the weld coefficient is specified as 0.85, which requires 100% PT testing for the joints. As for the flaw detection of coiled tubes, how can this be done in a way that is reasonable, legal, and cost-effective? Those who are interested, please come and discuss it. :)
The welding joint coefficient is taken as 0.85, with 20% RT applied
For the inspection of coil splicing, we follow the requirements for inspecting the splicing of heat exchange tubes.
There is also external coil cooling; when performing calculations for safety valves, how should this data be taken into account in the calculation software in order to offset the heat loss caused by the insulation layer?
For the main post, it is clearly inappropriate not to carry out non-destructive testing; at least a 20% inspection rate should be applied. Just because it’s outside the category doesn’t mean inspection shouldn’t be carried out – at the very least, this shouldn’t be stated openly; P. As for the calculation of the safety valve later on, it shouldn’t have anything to do with whether there are coils or insulation present, right?
How do I send a screenshot? I’ll send it and show you
Open the SW6 calculation software, navigate to the safety valve calculation page, and select the option for thermal insulation; in that case, it will be necessary to enter the thermal conductivity of the insulating material as well as the thickness of the insulation layer.
With such thin tubes, do you choose to use RT? Is it enough to just do a PT? For pipes on such equipment with a DN of less than 250 mm, surface treatment can be applied instead of RT.
Oh, it’s liquefied gas; that needs to be taken into consideration, namely the thermal conductivity and thickness. Equipment takeover is takeover; coils are coils. The coil is considered as a separate chamber and should be viewed as a device chamber.
Yes, that’s exactly it. But how is heat retention, heat dissipation, and coil heating calculated? The temperature level directly affects the rate at which the medium liquefies, and thus determines the size of the safety valve