The mounted storage of LPG with a floating foundation

The mounted storage of LPG with a floating foundation

Ten Bokkel Huinink, S.A.

Vrijling, J.K. (mentor)
Horvat, E. (mentor)
Noordhoek, C. (mentor)
Kremer, J. (mentor)

Civil Engineering and Geosciences

Hydraulic Engineering

1996-12-01

Because of the increase of safety requirements with respect to storage of LPG over the last ten years, underground storage is becoming increasingly significant. Storage is possible in engineering geological and in civil engineering constructions. The main features of these two solutions are presented. LPG can be stored either pressurized or refrigerated. This report concerns the pressurized storage in a civil construction. In mounded storage a horizontal cylindrical steel vessel is covered with sand. The normal mounded storage has some disadvantages which can be solved by partly submerging the vessel in the groundwater. This mode of storage is called mounded storage with a floating foundation. It is expected that using this method the differential settlements of the vessel will be smaller. Also the height of the mound will be smaller. A layer of sand on top of the vessel will prevent it from floating up. For some various sizes and shapes of the vessel the required thickness of this layer is calculated. In this report on the basis of a few criteria for the depth of the excavation and the length of the vessel the best alternative is chosen. For the chosen vessel the wall thicknesses are calculated and checked following the British Standard Specification for fusion-welded pressure vessels (BS 5500). A partly submerged vessel needs a coating and a cathodic protection system to prevent it from corroding. Exact the same coating and cathodic protection used for the normal mounded storage, can be used for the mounded storage with a floating foundation. The vessels will be shop-built in a tent close to their foundation. The foundation will be built in a dry excavation. With cranes the vessels will be put on their foundation. When the vessel is partly submerged the potential longitudinal bending moment in the vessel will be less. The differential settlement will be smaller but this does not effect the wall thicknesses since the dry situation is mandatory for the calculation of these sizes. The mounded storage with a floating foundation will be less expensive than storage in spheres, but more expensive than the normal mounded storage. However, other reasons than cost could perhaps make the mounded storage with a floating foundation a preferable storage method.

LPG storage
floating foundation

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Student theses

master thesis

(c) 1996 Ten Bokkel Huinink, S.A.