How-to Repair A Tube Bundle
A leaking tube in Niche Shell and Tube Fluoropolymer Heat Exchanger can be plugged easily once the bundle is removed from the shell.
1). Once the leak is located, cut the damaged fluoropolymer tube at the break and separate the two cut tube ends from the other tubes in the bundle.
2). Recut the tube about 6 to 8 inches (150 to 200 mm) from each end of the bundle. The fluoropolymer tube is now ready to be repaired.
3). Once a leak is located, it can be plugged using the same procedure as for shell and tube bundle repairs. Cut the damaged tube at the break, and separate the two cut tube ends from the other tubes in the bundle.
4). Recut the tube about 6 to 8 inches (150 to 200 mm) from each end of the coil. The damaged tube ends are now ready for repair.
5). Clean the inside of the tube using a pipe cleaner or cotton swab dipped in alcohol or another appropriate solvent.
6). Insert fluoropolymer plugging material into the tube end to a depth of approximately 1 inch ( 25.4 mm). Then, cut off about 1/8 inch (3 mm) of the tube and plug the material in one clean slice.
7). Apply heat to the end of the tube using a plastic weld gun with a temperature set at 600O to 700OF (316O to 371OC).
8). Once the tube and/or plug become clear, grasp the tube with a damp cloth or paper towel and gently squeeze the tube while rolling it with your fingers. This completes the repair to one tube end; both ends must be repaired before the coil may be restored to full service.
9). Most fluoropolymer tube leaks can be repaired with a plastic weld gun or by using a small, clean flame and flat-nose pliers.
10). Cut the tube at the leak, leaving enough tube remaining to move it away from the bundle.
11). Use a cotton swab and alcohol to clean the inside of both tube ends.
12). Apply an open flame to the tube at about 1/2 inch (13 mm) from the cut end; avoid depositing soot on the tube. Once the tube begins to sag or becomes clear in appearance, remove the flame.
13). Using the flat-nose pliers, crimp the hot section of the tube at about 1/2 inch (13mm) from the cut end. Apply firm, steady pressure for about 10 seconds, but do not pull on the tube.
14). Repeat this heating and crimping procedure for repairs to the other end of the tube.
15). For a stronger repair, insert plugging material into the cut tube before heating. Always use plugging material for tube diameters of 1/4 inch (6.4 mm) O.D. or larger; plugging material is available from Niche.
Niche Fluoropolymer is fast growing fluoropolymer manufacturers and capable of providing extremely corrosive and ultrahigh purity applications solutions.