Damage to Base of LNG Tanks from Blast Loading: Case Study

In July 1990, a series of five blasts took place about 200 m from two liquified natural gas (LNG) tanks belonging to Gaz Metropolitain in Montreal, Canada. One of the tanks lost its thermal insulation capacity at the base after the second blast. Massive cracking was discovered in the insulation material (foam glass), which had to be replaced. The replacement of the foam glass required a shutdown of the reservoir for about a year. This paper describes the analytical studies (static and dynamic) and experimental investigation that were performed to determine if the massive cracking was the result of the blast loading. The study of the available evidence and the numerical and experimental results show that the change in mechanical properties of the foam glass at low temperature, coupled with a low liquid level in the tank, shift the fundamental natural period of the base of the tank toward the predominant period of the blastinduced ground motion. The combination of these two effects induced the massive cracking of the foam glass.