Top Seven Shell and Tube Heat Exchanger Failure Mechanisms (#2 – Fouling)

#2 – Fouling…

Some processes are prone to solids forming inside the tubes. When you are working with those processes, you have to build a preventative maintenance program to keep the tubes as clear and clean as possible to ensure the heat exchanger can transfer heat as it’s intended.

A few methods of cleaning include rodding, rotating brush, high-pressure water blasting and chemical cleaning. The type of cleaning method employed is dependent upon how the material plates out and adheres inside the tubes. Sometimes, only chemical cleaning/recirculation will do the job but research into the various cleaning chemicals needs to occur because they can react with the tube base materials and cause metallurgical issues. It’s best to consult with your heat exchanger manufacturing and maintenance partners to ensure the best methods are being employed.

On exchangers where the fouling process is on the shell side (outside the tubes), it may be advantageous to design a removable bundle heat exchanger. Two common types are U-Tube Bundles and Floating Tube Sheet Bundles. With removable bundle designs, the tube bundle can be pulled out from the shell to provide full access to the outside of the tubes for cleaning. Specialty high pressure blasting is a common method of cleaning the outside of tubes. It’s important to remember that it can be difficult to fully clean the inside of the tubes in a U-Tube Bundle, as the bend at the far end sometimes limits the access with tube ID cleaning methods.

A fouled heat exchanger can bring your process to a screeching halt, creating pressure drop issues, reduced flow rates and compromised thermal performance.

When you are faced with a fouled heat exchanger, it’s great to have partners who not only can handle the cleaning/repair but also one who can build a new unit on an expedited basis to get your plant back up and running profitably.