A concrete or like articulated mattress for protection of seabed installations comprises a plurality of concrete elements (31, 32, 33, 34, 35) articulated together, the mattress having a relatively thick central block (33) from which its thickness tapers through side blocks (31, 32, 34, 35) to side edges (36, 37). In the central block (33) a tunnel (60) is provided to accomodate a seabed installation such as a pipeline to be protected. Prior to installation on a seabed, the side blocks (31, 32, 34, 35) may be folded over and stored on the top of the central block (33).

Seabed stabilization mattresses

The present invention provides a method and apparatus for constructing pipelines in Arctic offshore waters by a directional drilling technique, thereby minimizing exposure to ice gouging and eliminating the hazards associated with unstable permafrost. A special drilling-pipeline construction vessel is also provided which has a conical shape with reinforced outer walls to resist ice forces, which vessel includes means to install deep underground pipeline segments and means to connect and protect the pipe ends.

Pipelaying in artic offshore waters

The invention relates to an internal obturator for a pipe, particularly for a hydrocarbon conveying pipe-line, which comprises a central core and a flexible inflatable sleeve surrounding the core, wherein the central core comprises a flexible casing filled with a hardenable material which is hardened after its introduction into the flexible casing. The hardenable material may be hardened before or after insertion of the obturator into a pipe.

Inflatable internal pipe obturator with hardenable core

A kit is provided for temporarily blocking the bore of a pipe through which a fluid flows, the kit comprising an expansible flexible bag seal which is inserted through a hole provided in the wall of the pipe and an apparatus for injecting into the bag seal a quantity of a material adapted to expand in situ in the bag seal and inflate the bag seal to seal against the inside of the pipe. The pipe may be a gas main and the material may be an expandable synthetic resin foam. The bag seal is removed by injecting thereinto a substance capable of dissolving the foam so that the bag seal can be at least partially deflated.

Temporarily blocking the bore of a pipe through which a fluid flows with a foamed plug removed by dissolving

The method of ditching over a buried line involves making a hole, in advance of ditching, down to a level near a section of the buried line lying at the intersection with a proposed trench, spanning the line section with a line protector, and driving a ditching machine so that its excavating member makes the trench and in so doing rides in the trench over the protector and above the line section.

Sholukhov Vadim

Papers

Method of protecting hydraulic-fill pad of underwater pipeline from water stream action

Pipeline closing-off method

Method of determining pipeline blockage