In Gard we see that almost 50% of the cargo loss cases are a result of cargo contamination. Many of these are due to vapour contamination. Vapour contamination may occur due to migration of vapour between incompatible cargoes via the IG lines or from pre-existing vapours from the last cargo in the tank.
Contamination of petroleum products affects their odour, acidity or flashpoint specifications and can lead to the partial or total loss of the parcel thereby incurring significant losses. These losses can be avoided by ensuring that the IG branch valves are working in isolating tanks containing cargoes with different flashpoints. It is worth bearing in mind that IG line valves are subject to corrosive gases and may leak without warning. Remember to check their condition periodically and prior to loading incompatible cargoes.
Loss prevention poster http://www.gard.no/web/content/loss-prevention-posters#Contamination