If there are defects on the surface of stainless steel heat exchange tubes, they need to be repaired, and the repair method depends on the degree of damage.
We can classify different injuries into several levels:
Bronze level (shallow scratch repair)
Use 800 grit sandpaper as a scrubbing towel and rub it along the metal pattern until it reflects light; The polishing paste is used as a facial mask. After wiping, use a wool wheel disc to throw the heat exchange tube until it can be used as a mirror.
Silver Rank (Rust Spot Removal Technique)
Gently brush with a steel wire ball for mild floating rust (gentler than a steel wire brush without damaging the body); For severe rusting, spray a 10% sulfuric acid shower first, and after acid washing, use a passivation solution for skincare (to prevent secondary rusting).
Golden rank (first aid kit for pores/cracks)
The big pores of rice grains are directly grinded with a grinder, and then applied with 8112 repair agent as concealer (capable of withstanding 50 ℃ weak acid and alkali); The crack first opens a V-shaped groove along the crack, and the pit is slowly filled with argon arc welding. After welding, tempering therapy must be performed to eliminate stress.
King’s rank (weld defect repair)
Use tungsten inert gas arc welding to repair the biting edge, and gradually weld with the current reduced to 80A; The weld bead is directly flattened by a plasma cutting machine, and after repair, a radiographic inspection is performed.
When pickling stainless steel heat exchange tubes, attention should be paid to pouring water first and then adding sulfuric acid (not reversing), and welding wire of the same material should be used for repair welding! After the repair is completed, perform a pressure maintenance test on the stainless steel heat exchange tube: fill water and increase the pressure to 1.5 times the working pressure, and hold for 10 minutes without leakage to pass the test.