The first indication of tube leaks is often found due to changes in the condenser's condensate properties. Increased conductivity is recognized as a clear indication of tube leakage. Recently developed methods of water chemistry also look at pH and other properties.

When a condenser has cooling water leaks, identifying the leaks is the first step to isolating those leaks and understanding why the leaks happened in the first place. Finding the failed tubes so that they can be plugged can be done in a variety of ways, each of which has its strengths and drawbacks. A description of some of the most common methods is shown below.

Some condensers have divided water boxes that allow one side of a condenser’s tube bundle to be opened, while operating at reduced rates. This feature cannot be utilized to find tube failures. If one side of the condenser water boxed is drained and opened, any failed tubes will allow air to be pulled into the condenser. This has the potential to overload the system and result in a further loss of performance.

Once the failed tubes have been identified, they need to be plugged or replaced. When more than 10% of a bundle has been plugged, the condenser should be considered for replacement or re-tubing. It should be noted that as tubes are plugged the effective condensing surface area of the unit is reduced, which negatively impacts the condenser performance. Tubes are often plugged with a tapered tube plug made of a similar metal. For example, brass tubes would normally be plugged with a brass or copper tube plug. Using stainless plugs with brass tubes and tubesheets can deform the tube holes and prevent a new tube from being successfully expanded into that tubesheet hole. Various manufactures also make expandable tube plugs that are highly effective and may be selected when a higher degree of reliability is needed.

Understanding the cause of the tube failures is as important as identifying them. Once it’s known which tube(s) are failing, the cause of those failures can be investigated. There are a few common reasons why condenser tubes fail and they have been outlined below.

Another important test that is often utilized to evaluate the condition of condenser tubes is eddy current testing. Eddy current testing allows the equipment user to get an understanding of a condenser’s tube condition. This testing can help pick up defects within the tubes. It can also be used to evaluate how much tube wall loss has occurred, helping the user plan for the condenser replacement or repair. This testing is normally performed after the condenser tubes have been cleaned and at a set interval so that if any thinning or damage is identified a projected service life can be estimated.

If you are having issues with a condenser or have a condenser that has been in service for a long time and is in need of maintenance, please don’t hesitate to contact Graham for assistance. We would be more than glad to help review your installation and provide consulting services.

In addition to the condition of the tubes, the tubesheets, tube supports and internal air removal baffles should be evaluated. Damage to any of these items can drastically affect your condenser operation. Graham can supply tubes, tubesheets, parts, or complete replacement bundle kits for field installation to insure optimum efficiency of your condenser.