By Peter M. Tallman
CTI Industries, Inc.
It is common knowledge that many heat exchanger (HX) tube failures occur within the first 6 in. (150mm) of the bundle. Inlet-end erosion, stress corrosion cracking, and crevice corrosion are different types of failure mechanisms that are common in shell-and-tube HX.
In the past, the accepted repair for heat exchanger (HX) tube damage localized close to the inlet was full tube replacement or shortening of the tube bundle — despite the fact that more than 95% of its length usually remains undamaged. Either type of repair has proven extremely expensive and time consuming.
Accordingly, alternatives to full retubing repair long have been sought, including:
- Protecting damaged tube inlets.
- Restoring plugged leaking tubes to active service.
- Restoring original compressive strength to weakened tube-to-tube-sheet joints.
An acceptable repair should be cost effective and extend the life of the existing equipment.