Flange selection
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I have a question for everyone: For a fixed-tube-sheet heat exchanger with a nominal diameter of 400 mm, an operating pressure of 0.48/0.48 MPa (for the shell and tubes respectively), design temperatures of 200/200°C (for the shell and tubes respectively), and design pressures of 2.5/2.5 MPa (for the shell and tubes respectively), the JB/T 4703-2000 standard is applied; the flange type is FM 400-2.5. The ring weld between the flange and the shell must be at least 20% of the root thickness, and the acceptance grade is Grade III (according to JB/T 4730.2-2005). Are the selection of the flange for this equipment and the requirements for flaw detection of the shell appropriate? Looking forward to your reply! Thank you! !
If the thickness of the cylinder meets the requirements for Type B butt-welded flanges, then Type B butt-welded flanges of 4702 can be used; the weld between the flange and the cylinder shall meet the %MT or PT criteria, with Grade I as the acceptable standard.
If the medium is not flammable or explosive, it is possible to do this
Based solely on the given conditions and in accordance with flange standards, such flaw detection is acceptable, as it meets the requirements of 6.6.1.2 in JB/T4700. Of course, you also need to take the equipment parameters into comprehensive consideration.
Based on the conditions provided by the poster, the flange standard and flaw detection level chosen by the poster are both appropriate. The poster can also choose the JB4702 Type B flat welding flange; for flaw detection, in accordance with the provisions of 6.6.1.3 in 4700, the welds between the flange and the cylinder shall meet the Grade I criteria as determined by %MT or PT testing. Furthermore, the poster did not specify the composition of the medium – whether it is a flammable or explosive one
Since the design pressure is set so high, the butt welds between the flanges of 4703 and the cylinder may require 100% non-destructive testing; specific requirements can be found in those for 4700
4# Wen Bing Thank you all! ! May I ask how to understand the working pressure specified in item 6.6.1.2 of 4700? Can it be understood as the maximum allowable operating pressure? If it can be understood as the maximum required operating pressure, then is that the maximum allowable pressure when the design pressure is reached? In this case, my working pressure will be equal to the maximum allowable working pressure specified in standard 4700 (with the gasket material being 16Mn III). Therefore, the butt weld between the 4703 flange and the shell must be inspected using 1100% RT testing, and it is required to meet Grade I standards.
Take a closer look upstairs; it’s RT level 2, UT level 1. Don’t get it wrong
8# sprint0800 Thank you everyone! ! May I ask how to understand the working pressure specified in item 6.6.1.2 of 4700? Can it be understood as the maximum allowable operating pressure? If it can be understood as the maximum required operating pressure, then is that the maximum allowable pressure when the design pressure is reached? In this case, my working pressure will be equal to the maximum allowable working pressure specified in standard 4700 (with the gasket material being 16Mn III). Therefore, the butt weld between the 4703 flange and the shell must be inspected using 1100% RT testing, and it needs to meet Grade II acceptance criteria.