Repair Procedure for Heat Exchanger Coil

Repair Procedure Items to Prepare: –Repair kit provided by SK METAL – Filler Metal + SKA CP-70 Flux –Heat shields Tools to Prepare: –Needle nose pliers (long nose) –Stainless bristle brush –Portable LPG torch or oxygen–LPG torch ex) Turbo Torch Extreme (TX-503)

Repair Procedure Step 1: –To repair a leaking on the heat exchanger tube, First, check the exact area by conducting a leak test. –Note: The heat exchanger tubes are built to have an anti-shock attribute. However, handling the leaking area by using a sharp drill, knife, etc. may give a damage to the heat exchanger. Also, refrain from cutting off the leaking area from the tube.

Repair Procedure Step 2: If the leaking area can be repaired without removing the relevant air centers, you dont need to remove them. But, if you need to remove the air centers to approach the leaking area of the tube, it is recommended to use a needle nose pliers to remove them. Remove the air centers above and below the leaking area of the tube. Cut off the air centers up to about 25mm away from the leaking spot in both directions. Note: Since air centers are welded to the tube, they have to be torn off to be removed. Pay attention not to give a damage to the tube at this time. During the repair, completely remove the air centers in order to check, from the opposite side, if the repair of the leaking area has been conducted well. Sectional view of the tube after removing air centers to enough depth

Repair Procedure Step 3: –Remove all the remaining materials (such as fixed flux after welding, alien substances, etc.) on the leaking area by using the stainless bristle brush.

Repair Procedure Step 4 (Optional): After completely removing alien materials, cleanse the leaking area by spraying a detergent of a soap and water mixture (ex. dishwashing detergent) over the leaking area. And wipe out the detergent with clean water. Any remaining water should be completely dried by using the gas torch. Note: Make sure to wear protective clothing and pay attention to avoid a burn from splattered remaining water drops or from water vapor.

Repair Procedure Step 5: Spray enough amount of SKA-CP70 (Flux) over the leaking area.

Repair Procedure Tube nose repair Step 6a (Tube nose repair): –Cover surrounding air centers and tubes with metal heat shields so that only the leaking area is exposed.

Repair Procedure Step 6b –Place an iron plate mask that is rendered to expose the entire width and the length of the leaking area on the leaking area.

Repair Procedure Step 7: –Apply heat to the edges of the damaged area using the center of the torch or using the torch after setting its temperature to 450ºC- 500ºC. –Adjust the end of the electrode to the damaged area and gradually apply heat to the masked area and the tube parallel to the damaged area until the welding material is melt into the core tube area. –Cool down the heat and remove the mask. –Note: Since the tube walls are very thin, applying excessive amount of heat may cause an overheating through the tube walls.

Repair Procedure Step 8 (Optional): –Substitution of air centers with removed ones in the Step 2. –Cut substituting air centers in the size that matches the width and the length of the removed one by using a scissors, etc. –Fixate the substituting air centers by using a metal adhesive. Ex) (Loctite 430) – metal adhesive

Repair Procedure Step 9 (Optional): Fixate the inserted air centers by using an instant adhesive (Loctite 430).

Repair Procedure Step 10: –Apply anti-corrosive spray over the repaired area and its opposite side to prevent a corrosion.