Hi, I think pre-shipment inspection is not enough and can not disclose all defects. The scope of work for Pre-Shipment inspection is visual quality not quality. In visual quality the appearance of commodity will be check and also quality control record will be reviewed. But in quality inspection is that a independent inspection agency attend to the manufacturing shop and witness some important tests. So for such case you need to carry out vendor inspection and test instead pre-shipment inspection. Pre-shipment inspection has commercial approach but vendor inspection has technical approach.
regards