Non-destructive evaluation of impact damaged composite pipes and pipe couplings with bond line defects

An ultrasonic technique using the commercially available ANDSCAN system has been used to assess impact damage in filament wound glass reinforced epoxy pipe subjected to seawater at the rated internal pressure, 20 bar (2MPa) at ambient temperature. The ultrasonic method developed has been used to quantitatively examine pipes impact damaged by three different nose-shaped indenters, both before and after exposure to seawater. Ultrasonic measurements of the extent of the damage have been compared with measurements taken from micrographs of sections of the damaged regions. A similar ultrasonic method has been used to detect and quantify lack-of-bond defects in adhesively bonded couplings. The test results show that impact damaged pipe exposed to seawater at the rated pressure for up to 6 months display no increase in the extent of the damaged region. Whilst in each test the pipes leaked from the damaged region initially, the leakage declined to almost zero over a maximum of about 20 weeks, depending on the nose-shape of the indenter. Ultrasonic measurements of the extent and distribution of the damage through the pipe wall agreed well with measurements taken from micrographs. Good agreement has also been achieved with the ultrasonic measurement of the lack-of-bond defects in the adhesively bonded couplings. The results have demonstrated that the ultrasonic method developed is an effective technique for the evaluation of impact damage in pipes and for the detection of lack-of-bond defects in couplings.