Evaluation of pits in GRP composite pipes by thermal NDT technique

Abstract

In recent years, pipeline operators face many threats to the integrity of pipelines and hence, sophisticated nondestructive testing (NDT) technologies and measuring devices are being used for diagnosing the pipeline conditions. The presence of various defects is almost common during manufacturing, handling and under servicing conditions of glass-fibre reinforced polymers (GRP) composite pipes. Among various defects, severe pits or wall loss defects can be internally produced after a certain period of time due to various practical reasons. The present study has been taken up to analyse theviability and effectiveness of thermal NDT techniquein the evaluation of pits in GRP pipes. The thermal contrast evaluation profiles are obtained from number of experiments conducted on GRP pipes with artificially induced pits and the effect of pit size and its penetrationare analysed. The results show that the largerand deeper pits can be detected faster with increased thermal contrast and vice-versa. The investigation shows that the method leads a simple approach in applying thermal NDT to evaluate pits in GRP pipes.