Abstract: Welding technology is widely used in the connection and production of special key components under pressure. Mastering non-destructive testing and repair technology is of great significance for ensuring the safe operation of key equipment such as nuclear power, hydropower, chemical industry, and machinery. Classify the characteristics, welding environment, and repair difficulties of WSTE36 welding material for the bottom head of the adsorption tower in the xylene unit. Use TOFD technology to detect defects in the weld seam of the bottom head of the adsorption tower in the xylene unit, determine the size and location of the defects, develop a reasonable repair plan based on the defect category, and eliminate defects and repair equipment through methods such as air gouging.To avoid increasing the number of repairs, multiple defect inspections can be conducted to accurately locate the defect location. When carrying out air gouging to eliminate defects, control the angle and process. In the early stage,use large process gouging, and in the later stage, use an angle grinder for small process polishing. During the heat treatment process, implement multi-point temperature control and real-time temperature monitoring to avoid adverse effects on the adsorbent caused by high temperature and affecting the quality of repair. After the repair is completed,TOFD technology is used to perform defect detection on the equipment again until it is fully repaired. The application and summary of on-site repair technology for weld defects in the bottom head of the adsorption tower of the xylene unit provide experience and reference for welding defect detection and repair of similar equipment,and lay a foundation for ensuring the safe operation of key pressure equipment in nuclear power, chemical industry,important machinery and other fields.