（What could be the probable cause of dents with plastic jerricans also with steel drums.）
An air shipment of liquid chemicals packed in single packaging plastic jerrican and also in single packaging steel drum suffered dents on the body near the bottom chime. There were no scratches nor traces of physical impact. The bodies of the jerrican and the drum were simply caved inward. Fortunately, there were no loss of contents. The airline informs there were no turbulences recorded during the entire journey and the jerrican and drum were tightly secured in the cargo compartment. The airline claims that the jerrican and the drum may not have passed the pressure differential test of 95 kPa required for UN specification packagings. However, we feel that the lowered cargo compartment pressure would have caused a swelling of the body and could not have caused an inward dent. (31 Aug 14)
It is advisable to secure the UN test certificates of the jerrican and drum to double check whether they have passed the pressure differential test of 95 kPa. Other than dents caused by pressure differential, it is difficult to ascertain the cause of the inward dent when there are no scratches nor traces of physical impact.