I. Core Quality Assurance Measures
1. Non-destructive Testing Re-inspection: The repaired area must be re-tested using ultrasonic testing (UT) or eddy current testing (ET), focusing on checking for residual cracks or new defects. Especially after grinding and turning, it is necessary to confirm the absence of new fatigue sources.
2. Hydrostatic Testing to Verify Sealing: A pressure test should be conducted at 1.5 times the working pressure for at least 10 seconds to ensure no leakage or plastic deformation in the repaired area, meeting the requirements of GB/T 241-2007 standard.
3. Dimensional Accuracy Verification: The outer diameter and wall thickness of the repaired area should be measured using tools such as an ultrasonic thickness gauge and micrometer to ensure that the wall thickness is not lower than the design minimum (generally, it should not exceed a negative deviation of 10%), avoiding weakening the pressure-bearing capacity.
4. Surface Quality Inspection: The repaired surface should have a smooth transition, without sharp corners, pits, or high points to prevent stress concentration. Magnetic particle testing (MT) should be performed if necessary to confirm the absence of surface opening defects.
II. Applicable Standards and Prohibited Uses
1. According to GB/T 8163-2023, seamless steel pipes used for conveying flammable or toxic media are not permitted to undergo any form of defect repair. If a defect is discovered, the entire pipe must be scrapped.
2. Repair of shallow surface defects in non-pressure, low-pressure systems or structural pipes is only permitted, and the entire process must be recorded and traceable.
⚠️ Safety Bottom Line: No repair may be performed at the expense of safety. Repairs involving internal defects (such as internal folds, inclusions, and porosity) or penetrating damage are strictly prohibited.
