Mcdermott Incorporated

Derek T Fern

Gary E Harrison

Apparatus for preventing flow of water from a first underwater pipeline portion forward of the apparatus to a second underwater pipeline portion rearward of the apparatus. At least one wedge-shaped member is mounted on a carriage of the apparatus for grippingly engaging the internal wall of a pipeline for preventing movement of the apparatus in a rearwardly direction upon application of force to the carriage urging the carriage in a rearwardly direction in the pipeline. In order to provide frictional contact with the pipeline wall so that gripping engagement thereof may be effected, the member is continually urged into sliding engagement with the pipeline wall during movement of the apparatus through the pipeline in a forwardly direction. The apparatus is further provided with an annular elastomeric member responsive to water pressure from forwardly of the apparatus for sealingly engaging the pipeline wall to prevent flow of water from the first underwater pipeline portion to the second underwater pipeline portion.

Underwater pipeline sealing apparatus

An offshore structure and a method of sinking it to the sea bed. In accordance with one aspect of this invention, the structure is sunk asymmetrically by first sinking a first end portion thereof and then sinking the other end portion. The first end portion is sunk by ballasting it while the other end portion is closed to ballast. The structure is provided with sufficient water plane area while sinking each end portion to maintain stability during the sinking process. In accordance with another aspect of this invention, at least two spaced-apart piles are provided at the end corresponding to the first end portion to absorb the force of impact with the sea bed and to maintain a skirt on the structure out of contact with the sea bed until both ends of the structure have been sunk to the sea bed.

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Gretna, LA, United States of America

Derek T Fern