How Heat Exchanger Tubes Should Be Repaired

Leakage points
There are generally two places where heat exchanger tubes leak in a pressure vessel, one is the connection of the tubes and the other is the leakage of the tubes themselves.
Handling of leakage at the tube connection
There are three main methods of connecting tubes and tube sheets: expansion joint, welding, welding and expansion joint. Expansion of the tube due to temperature, pressure fluctuations and temperature deformation of the uneven, resulting in the tube from the tube plate to pull off, loose and leakage, can be taken to fill the expansion to eliminate leakage, such as ineffective, can be carried out again, make up the expansion can not be more than three times, otherwise it will be made at the hole of the tube plate material cold hardening and expansion of the hole is not tight.
Ineffective for the complementary expansion of the need to replace the pipe or take the welding method. It should be noted that after welding, the need to expand the surrounding pipe again, because after welding due to thermal expansion and contraction of the tube plate will cause leakage around the other tube expansion joints. If it is a leakage of the weld seam between the tube and the tube plate, it can be polished and patch welded to deal with it.

Handling of leakage of the pipe itself
Heat exchanger tube due to corrosion, abrasion, erosion, deposition of corrosion and other reasons, often resulting in cracks, perforation and leakage of the tube. Leakage of the tube itself is generally not repairable, if the number of leaking tubes is not much, you can use a conical metal plug to plug the ends of the tube mouth, such as the tube and the pressure is higher, tightly plugged and then welded to be more reliable. The length of the metal plug is generally twice the inner diameter of the tube, the diameter of the small end should be equal to 85% of the inner diameter, taper 1:10.
The hardness of the plug material should be lower or equal to the hardness of the tube. When the tube is plugged to eliminate leakage, the number of plugged tubes shall not exceed 10%. When one end of the stainless steel heat exchanger tube is damaged, the tube pulling repair method can also be used, this is because the elongation of the stainless steel tube is 40% to 45%, when the total elongation of the tube pulling is not more than 12%, the tube can be pulled several times.