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Down Tube Coating: Eliminating Condenser Tube Leaks at the Source
A main condenser was experiencing leaks in a number of tubes as well as leaking at the tube-to-tubesheet joint. Down tube coating was selected as the most cost-effective method to eliminate pinhole leaks and prevent future tube end erosion and corrosion.
The Problem
Tube Leaks and Joint Failure in a Main Condenser
A main condenser was experiencing leaks in a number of tubes as well as leaking at the tube-to-tubesheet joint. Down tube coating was selected as the most cost-effective method to eliminate pinhole leaks and prevent future tube end erosion and corrosion.
Specification
Epoxy Primer and Topcoat — Tubes and Tubesheet Applied Simultaneously
Application
Tube Internals & Tubesheet Face
Tube DFT
6–8 mils (5 coats)
Tubesheet DFT
40 mils (5 coats)
Application Method
A tube roller on the end of an air drill was used to apply coating down the tube length. An adjustable guide on the shaft controlled depth of penetration.
Film Build Control
Each successive coat shortened the application depth by 1/4 inch to ensure proper film build at the tube end without bridging the tube-to-tubesheet joint.
The Result
Pinhole leaks eliminated.
Tube end erosion and corrosion prevented.
Tube-to-tubesheet joint leaking eliminated.
Industries: Power Generation
Categories: Maintenance & Repair