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The forms of corrosion defects in pressure vessels and their treatment methods are as follows: 01 Pitting corrosion – in the following three cases, it is considered a minor defect and may not require treatment for now. (1) Large pitting corrosion areas, but no cracks ； (2) Scattered corrosion pits, the maximum corrosion depth of which has not yet exceeded half of the wall thickness required for calculating the container’s strength (excluding the thickness taken into account for corrosion allowance) ； (3) Within the dispersed pitting areas, there is no severe chain-like pitting. 02 For individual subcutaneous corrosion defects and isolated pit corrosion defects with an area not exceeding ø40mm, there are three treatment methods. (1) When it is shallow, no action may be taken for now ； (2) When it is relatively deep, the grinding method can be employed; however, the wall thickness must meet the strength requirements after grinding ； (3) If the strength requirements cannot be met after grinding, surfacing welding should be employed. 03 When several larger pit defects with a single area diameter not exceeding ø40mm exist simultaneously, there are two scenarios. (1) When the distance between two adjacent defects is greater than 120 mm, they can be treated as individual pitting corrosion defects ； (2) When the distance between two adjacent defects is less than 120 mm and greater than 50 mm, and the corrosion depth does not exceed 60% of the original wall thickness, surfacing treatment can be applied. 04 For localized corrosion defects whose depth does not affect the strength requirements but which have a large area (such as large-scale spots or ulcerative corrosion), metal spraying can be used as a treatment method. 05 Local uniform corrosion defects can be treated in the following three ways. (1) The corrosion area can be large or small; as long as the depth of the defect does not exceed 40% of the original thickness of the wall, surfacing treatment can be applied ； (2) When several defects of uniform corrosion exist simultaneously, with each defect having an area of no more than 50mm×50mm, the distance between adjacent corroded areas being greater than 50mm, and the depth of the defects not exceeding 60% of the original thickness of the wall, surfacing treatment can be applied ； (3) When there are too many corrosion patches or they are spread over a large area, patching can be used, or the defective tube sections or cylinder bodies can be replaced. 06 General uniform corrosion defects are the least hazardous type of corrosion defects; generally, only anti-corrosion measures are taken, with no other treatments required. 07 Intergranular corrosion defects are among the most dangerous types of defects. For such defects, preventive measures are primarily employed; otherwise, once they occur, the entire component must be replaced.