How is an F-Style can repaired and accepted?
Nov 12, 2025
I. Pre-Acceptance Preparation
1. Defect Inspection and Repair Plan
Before repair, a comprehensive quality inspection must be conducted in accordance with the "Key Points for Opening Inspection of Spherical Tanks" to identify the cause of the defect and develop a repair plan. After approval by the technical director, this plan must be submitted to the competent authority for filing. If the defect is complex, an expert review of the repair plan must be conducted, and the inspection cycle and expected service life must be clearly defined.
2. Repair Unit Qualifications
The repair unit must possess relevant pressure vessel qualifications, and the repair process must comply with the "Regulations on Safety Technical Supervision of Stationary Pressure Vessels" (TSG 21-2016).
II. Acceptance Content and Methods
1. Macroscopic Inspection
Inspect the tank's geometric dimensions (such as wall height, verticality, and local deformation) to ensure they meet design standards.
The welds must be free of defects such as undercuts and convexities. Parameters such as misalignment and excess height must meet regulatory requirements.
2. Tightness Test
Fill the tank to the designed level and maintain for 48 hours to inspect for leaks and deformation in the tank wall. The tank bottom must be leak-free. Negative Pressure Test: When the water level is reduced to the maximum, seal the tank roof and test its stability under negative pressure. The tank roof should show no abnormal deformation.
3. Nondestructive Testing
Welds should be inspected using ultrasonic, magnetic particle, or penetrant testing. Internal defects must be retested after repair. The same area should not be repaired more than twice.
III. Acceptance Organization and Standards
1. Inspection Batch Division
Inspection batches should be divided according to sub-projects. The supervisory unit will conduct the inspection and issue the results. Key control items must meet 100% standards, and general items must meet at least 80% of the standards.
2. Document Requirements
Repair plans, test reports, and material qualification certificates must be provided. Special operations personnel must be certified.
IV. Special Precautions
F-Style cans with a design temperature <= -20℃ or imported from abroad are not subject to conventional repair standards.
The water temperature during the water filling test must be >= 5℃. Foundation settlement must be monitored throughout the entire process. Testing should be suspended if abnormalities occur.
