First, a comprehensive inspection of the heat exchanger tube’s appearance is performed, focusing on surface defects such as cracks, scratches, pits, bulges, scale, and rust. Welds should be inspected specifically for weld beading, incomplete penetration, porosity, and slag inclusions, as these defects can directly affect the tube’s sealing and pressure-bearing capacity. For heat exchanger tubes exposed to corrosive media, special attention should be paid to inspecting the tube wall for uniform corrosion, particularly at vulnerable areas such as the inlet and outlet ports and U-bends, as these areas are often the first to show signs of corrosion thinning.

Wall thickness measurement is a core inspection item. An ultrasonic thickness gauge is used to measure the heat exchanger tube at multiple points, focusing on tube-sheet joints and sections identified as problematic during previous inspections. The measured data should be compared with the original design wall thickness. Any wall thinning exceeding the design allowable value must be addressed promptly. For heat exchanger tubes exposed to high-temperature and high-pressure conditions, creep testing is also required. Metallographic analysis is used to assess material microstructure degradation and to measure the tube diameter for expansion and deformation beyond the allowable range.

Leak inspection is crucial to ensuring the safe operation of heat exchangers. This can be performed using methods such as pressure testing, helium leak detection, or ultrasonic testing. During inspection, special attention should be paid to the sealing performance at the joints between the tube sheet and the heat exchange tubes, as these areas are prone to leakage under thermal cycling stress. For heat exchangers with threaded locking rings, the tightening of the threaded locking rings and the wear of the sealing surfaces should also be checked.

Inspection of the supporting structure is also crucial. Components such as baffles and support plates should be checked for deformation or displacement to ensure that the heat exchange tubes do not suffer fatigue damage due to vibration during operation. For fin-tube heat exchangers, the integrity of the fins and pitch variations should also be checked. Accumulation of dust and scale can affect heat transfer efficiency. If corrosion or fouling is detected during inspection, they should be cleaned or replaced promptly. Cleaning methods include high-pressure water jet flushing, chemical cleaning, or the use of specialized equipment such as mobile descaling machines.

The inspection frequency depends on the operating environment and working conditions. Generally, industrial equipment requires a comprehensive inspection at least annually, and newly built pipelines should undergo the first comprehensive inspection within three years of commissioning. For corrosive media or high-temperature, high-pressure environments, the inspection cycle should be shortened to 6-12 months. Inspection results should be carefully recorded and archived to provide data support for subsequent maintenance. Through systematic, regular inspections, potential problems can be identified and addressed promptly, ensuring the safe and stable operation of stainless steel heat exchange tubes.