Retubing bundles

Retubing bundles every two years is not unusual. To prevent excessive tube failures, keep the tube bundle submerged in liquid. Place a prominent red line on the level gauge glass to show the operators the height of the tube bundle. A pattern of tube failures near the top of the bundle indicates the operators are often running at too low a liquid level. 

If leaks develop at the inboard tubesheet, they cannot be easily stopped by plugging the tube. If rerolling the tubes does not stop the leaks, it may be necessary to retube the bundle. The tubes cannot be feasibly welded to the inboard tubesheet. 

The Rajasthan Unit-2 has been restarted after retubing. In this reactor, about 250 kg of thorium was loaded for initial power flattening. The thoria bundle distribution is different here from that of Kakrapar Unifs 1 and 2. This is because Kakrapar uses shutoff rods for reactor scram, and so the thoria bundle locations have to be chosen in such a manner as... 

Reclaiming MEA is a tough service for carbon steel tubes. Certain stainless steels cannot be used in most refinery applications because chlorides concentrate in the boiling liquid and cause stress corrosion cracking (see Chapter 22). (316 S.S. is one of the better materials used for bundle retubing in this service.)... 

Reboilers. Remove tubes to form vertical or diagonal vapor passageways through the bundle. This reduces turbulent boiling in the shell. Retubing with 304 stainless tubes will reduce corrosion if the amine is low in chlorides. Otherwise use 316(L) or 317 S.S. 

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