(49e) Unusual Corrosion Failures of Transfer Line Exchangers

This paper describes two case histories of corrosion failures. The first case history describes metal dusting of the tubes and tubesheet from the process side in the horizontal TLE. The tubesheet of TLE was overlayed with Alloy 625 to prevent erosion. Deposition on the waterside allowed higher than expected temperatures to occur at the hot tubesheet on the process side, leading to metal dusting of tubes in less than two years.

The second case history describes galvanically accelerated corrosion on the waterside of the tubes. Copper removal from condenser tubes and deposition on the OD of the TLE tubes caused the failures. Failures were located on the cool end of vertical TLE.

Failure analysis, inspections, repairs and solutions for these failures will be discussed.

Both case histories explain ?Back to Basics?, proper maintenance and monitoring of proper water chemistry.