Heat exchanger tube plugs are used to seal leaking heat exchanger tubes, prevent damage to adjacent tubes, and keep aging heat exchangers as efficient as possible. JNT Technical Services’ Torq N’ Seal® Heat Exchanger Plugs provide a quick, easy and effective way to seal heat exchangers with leaks up to 7000 psi. Whether you have feed water heaters, lube oil coolers, condensers, or any other type of heat exchanger, knowing how to properly seal leaking pipes will reduce repair time, reduce project costs, and maximize equipment life. This article will look at how to properly plug a leaking heat exchanger tube.
There are several ways to detect leaks in heat exchanger tubes: pressure leak test, vacuum leak test, eddy current test, hydrostatic test, acoustic test, and radio indicators, just to name a few. The correct method for a given heat exchanger depends on the maintenance requirements associated with that heat exchanger. For example, a critical feedwater heater often needs to be plugged to a minimum wall thickness before a leak can occur. For these applications, eddy current or acoustic testing would be the best choice. On the other hand, condenser arrays with significant excess power can handle a certain amount of leakage tubes without affecting the process. In this case vacuum or crimping is the best choice due to their low cost and ease of use.
Now that all pipe leaks (or pipes with thin walls below the minimum allowable thickness) have been identified, it’s time to start the pipe plugging process. The first step is to remove any loose scale or corrosive oxides from the inside diameter surface of the pipe. Use a slightly larger hand tube brush or sandpaper on your fingers. Gently move the brush or cloth inside the tube to remove any loose material. Two to three passes are enough, the goal is simply to remove loose material, not to change the size of the tube.
Then confirm the tubing size by measuring the tubing inside diameter (ID) with a three-point micrometer or a standard caliper. If you are using a caliper, take at least three readings and average them together to get a valid ID. If you only have one ruler, use more average measurements. Verify that the measured diameter matches the design diameter indicated on the U-1 data sheet or on the heat exchanger nameplate. The handset must also be confirmed at this stage. It must also be indicated in the U-1 data sheet or on the nameplate of the heat exchanger.
At this point, you have identified the leaking tubing, cleaned it carefully, and confirmed the size and material. Now is the time to choose the right heat exchanger tube cap:
Step 1: Take the measured inside diameter of the pipe and round it up to the nearest thousandth. Remove the leading “0″ and the decimal point.
Alternatively, you can contact JNT technical service and one of our engineers can help you assign a part number. You can also use the plug selector found at www.torq-n-seal.com/contact-us/plug-selector.
Install a 3/8″ square drive torque wrench to the recommended torque indicated on the box of Torq N’ Seal plugs. Attach a hex head screwdriver (included with every package of Torq N’ Seal plugs) to the torque wrench. Then secure the Torq N’ plug Seal on the hex screwdriver Insert the plug into the tube so that the back of the screw is flush with the surface of the tube sheet Slowly turn clockwise until the torque wrench clicks out Pull out the hex drive of the gripper Your tube is now sealed to 7000 psi.
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