酸環境で長期間使用されたGFRP製タンクの損傷状態と超音波エコー測定に基づく劣化診断

抄録

This study was conducted to investigate damage conditions of a large GFRP tank which was employed in the chemical industry to store mixture of nitric acid and phosphoric acid during 19 years. Further, an attempt was made to establish a damage inspection method based on ultrasonic echo measurement for GFRP products. Detailed optical observations were carried out on the inside surface and cross-section of four typical positions of the tank. The results showed that the acid environment invaded the inside of GFRP through cracks and pin holes made on the inside surface of the tank, and then the environment gave remarkable damage to chopped strand mats existing under a surfacing mat. Degree of the damage was adequately predicted, using ultrasonic echo data. Although the above inspection method could predict decrease in the strength of the roof part which suffered severe damage, further investigation was needed to predict remaining strengths of parts where damage was relatively mild.