Coil non-destructive testing methods
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Hello everyone, we currently have one tank of DN2000X3000, with a thickness of 10, an operating temperature of 35-40, and the medium is steam and condensed water. It is planned to install two coil units internally: one with a total length of 35m and the other two with a length of 70m each. The operating temperature for these coils is 30–40°C, the gauge pressure is 0.3 Mpa, the pipe diameter is DN40, and the wall thickness is 4 mm. The question is: regarding non-destructive testing, how should the coils be selected? What is the proportion, what’s the level?
The coiled tubes require 100% non-destructive testing; if it is strictly prohibited for the medium inside the tank to mix with the condensate water inside the coiled tubes, then RT testing shall be conducted, with a grade of III being considered acceptable. Then, a hydrostatic test at 2 times the design pressure was conducted and passed.
100% RT, grade II or III?
I wonder, why would the water pressure need to be twice as high, if the medium is water in both cases?
The hydrostatic test pressure is determined by the designer. Our design institute has established such rules; it is also possible to use 1.5 times the design pressure and then take into account temperature adjustments to determine the value
The inner diameter of the coil is less than 150 mm, so it does not qualify as a pressure vessel; the proportion of non-destructive testing is determined by the supplier and the buyer or by the standards applicable to such vessels.
RT can be used for small-diameter pipes, but some manufacturers say they are unwilling to do it; moreover, TIG welding as a backing process ensures quality. For small-diameter pipes, we generally carry out surface inspections.
Hello, regarding the classification of pressure vessels, vessels with an inner diameter of less than 150 mm are not considered pressure vessels. How is the coil determined here? Is it based on this rule?
Yes. Refer to Article 1.3 of TSG21-2016 \"Regulations on Solid Waste Storage\"