The heat exchangers are connected in series to form one device
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Question: A heat exchanger consists of two shell-side cylinder sections and three tube-box cylinder sections, with a section in the middle serving as the tube box that connects to the shell sides at both ends. The operating temperature is 500 for the shell side and 460 for the tube side; long-neck butt weld flanges are used, with materials of 304 and Inconel 600 respectively. How should the connection structure be designed for the middle section? If flanges are used as the connection mechanism for ease of installation and disassembly, can the two long-neck flanges be directly welded together? Are there forgings with two flanges joined together as a single unit? Additionally, at 500 degrees, how can one determine whether there is a tendency for intergranular corrosion in 304? Thank you!
Connect them with elbows in the middle； Long-neck butt-weld flanges should be compatible, but there are also flange fittings according to GB/T17815 ； Intergranular corrosion depends on the medium. I’m a beginner; the above are just my humble opinions…………
In practical applications, the most common configuration is two devices connected in series
As long as there is enough space, butt welding two long-neck flanges should not be a problem
As long as there is enough space, butt welding two long-neck flanges should not present any problems. Regarding intergranular corrosion: when austenitic stainless steel is exposed to temperatures between 450–850°C for an extended period of time (these temperatures are commonly referred to as sensitization temperatures), chromium carbides precipitate at the grain boundaries, reducing the chromium content in the austenite near those boundaries below the level required for passivation.