Journal of High Pressure Institute of Japan

Recently, the deterioration and the degradation advances in the concrete structure. Repairing materials are injected into its crack and pore in order to obtain the strength of the concrete. This paper proposes the repair situation of crack and adhesion using the rectangular diffraction method (Lamp method) of ultrasonic wave testing. It is possible to know the existence of the crack in the concrete by the rectangular diffraction method. In the first wave of ultrasonic waveform, the waveform got from the place without the defect becomes upward. However, the waveform from the defect becomes downward. It is possible to examine the injection situation of repairing materials to artificiality crack and natural crack. In the healthy division where the tiles are perfectly bonded together, the first wave shows the upward waveform, and the downward waveform is shown in the unhealthy division.

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Fitness-for-service (FFS) assessments are quantitative engineering evaluations performed to assess the structural integrity of an in-service component that may be flawed or damaged. The FFS standard committee of the Petroleum Association of Japan and the Japan Petrochemical Industry Association is developing the Japanese FFS standard based on the API⁄ASME FFS code for metal loss assessment using the finite element method (FEM) . The FEM is described in ANNEX B in API-579-1⁄ASME FFS-1. As stated therein, evaluations of at least plastic collapse (B 1. 2) and local failure (B 1. 3) are required to be performed for the assessment of metal loss.
The FFS standard committee members calculated the acceptable pressure inside a cylindrical shell with local metal loss by the FEM using burst test data obtained from a public database, in order to estimate the safety margin of the burst pressure.
It was found that the accuracy of the acceptable pressure for plastic collapse calculated by the committee members varied within 5% of the safety margin despite the use of the same software and FEM mesh; the safety margin is defined as the ratio of the burst pressure to the calculated acceptable pressure and is approximately equal to Safety Factor in the Code.
Further, the safety margin of the hand-calculated acceptable pressure described in Part 5 of API-579-1⁄ASME FFS-1 is more conservative than that of the FEM results.

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