Waigaoqiao Shipbuilding successfully applied TOFD nondestructive testing technology for the first time

A few days ago, the three 18,000 TEU ultra-large container ships that Shanghai Overseas Takahashi Shipbuilding Co., Ltd. first built were all delivered smoothly. During the period, the ultrasonic diffraction time difference (TOFD) nondestructive testing technology jointly developed by the company and the Shanghai Ship Technology Research Institute was successfully applied for the first time.

The 18000TEU ultra-large container ship uses EH40 and EH47 high-strength steel in the torsion box and hatch area. Thanks to its thickness of 85 mm, the quality of the welding is essential for the smooth construction of the entire ship. Waigaoqiao Shipbuilding Co., Ltd. carried out special research on this, and formed the “Quality Control Procedure for the Construction Process of 18000 TEU Container Ship Super Heavy Plate Structure”, from personnel, steel pretreatment, cutting, assembly, welding, nondestructive testing, inspection and inspection, etc. In one aspect, the quality management of ultra-thick board processing was planned, and TOFD non-destructive testing technology was applied for the first time.

TOFD non-destructive testing technology is an enhanced detection technology. Compared with traditional ultrasonic (UT) detection technology, it has the advantages of high detection results, high defect detection rate, fast detection speed, and intuitive detection images, especially for accurate detection. The height of the crack in the weld is easy to analyze and evaluate the potential threat of the crack to the ship structure, which plays an important role in ensuring the construction quality of the ultra-large container ship. To this end, in the initial stage of the construction of the 18000 TEU ultra-large container ship, Waigaoqiao Shipbuilding Co., Ltd. and Shanghai Shipbuilding Quality Inspection Co., Ltd., affiliated to the Shanghai Institute of Marine Industry, set up a research group on TOFD non-destructive testing technology to jointly carry out technical research.

The 18000TEU ultra-large container ship TOFD inspection project was completed in early 2014. In October of the same year, the TOFD inspection process passed the final review of the French Bureau of Shipping (BV) and began on-site inspection. In March 2015, the TOFD inspection was completed. The weld length was 488 meters and the image data acquisition was complete. The degree is higher than 98%, and the record is clear, informative and traceable. In the joint research process, Shanghai Ship Engineering Quality Inspection Co., Ltd. and Waigaoqiao Shipbuilding Co., Ltd. work closely together on the quality standards, equipment selection, process formulation, and interpretation of the TOFD inspection of high-strength ultra-thick plate welds. Utilizing the technical resources of China Shipbuilding Non-destructive Testing Center, it solved many technical problems and achieved many industry firsts. The testing process and results were unanimously recognized by BV and the shipowner, and achieved good results. At present, the research team has begun to apply this technology to the hull structure and ship pipe welds.

Industry experts believe that the successful research of this topic shows that TOFD non-destructive testing technology has officially moved from the scientific research stage to the application stage in China's shipbuilding industry. The relevant testing capabilities and levels have also reached the international first-class level, adding a new quality control for shipbuilding. Scientific methods and means, and laid a solid foundation for the construction of 20,000 TEU ultra-large container ships and high-end offshore products.

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