Abstract: A closure for a pipe or pressure vessel comprises a door adapted to fit into an aperture in a pipe or pressure vessel and an arcuate locking member disposed around the periphery of the door for locking the door to the pipe or pressure vessel, the ends of the locking member being movable towards and away from each other to cause radial expansion and contraction of the locking member, whereby the locking member is brought into and out of locking engagement with the pipe or pressure vessel. A seal for the closure comprises a rigid, usually annular, support having first and second flanges for engaging respective opposed faces on the closure and the pipe or pressure vessel, the first flange having a greater surface area and being less flexible than the second flange, and a flexible lining carried by the support and extending beyond the terminal edges of the flanges.

Abstract: A sphere for use in the "pigging" of pipelines has a number of discrete areas of abrasive material (2) on its surface. The abrasive material may comprise a flexible backing provided with a multiplicity of upstanding spikes or fibres, mounted in shallow depressions in the surface of the sphere so that the free ends of the spikes or fibres may contact the pipeline wall. The shallow depressions accommodating the abrasive material are suitably interconnected by a network of shallow channels (3). The spheres (1) are of particular use in the "pigging" of lateral feeders to a main pipeline, wherein it may not be possible to use the cylindrical or piston form of pig.

Abstract: A closure for a pipe or pressure vessel comprises a door adapted to fit into an aperture in a pipe or pressure vessel and an arcuate locking member disposed around the periphery of the door for locking the door to the pipe or pressure vessel, the ends of the locking member being movable towards and away from each other to cause radial expansion and contraction of the locking member, whereby the locking member is brought into and out of locking engagement with the pipe or pressure vessel. A seal for the closure comprises a rigid, usually annular, support having first and second flanges for engaging respective opposed faces on the closure and the pipe or pressure vessel, the first flange having a greater surface area and being less flexible than the second flange, and a flexible lining carried by the support and extending beyond the terminal edges of the flanges.

Abstract: A closure member for a pipe or pressure vessel, comprising a door adapted to fit an aperture in the body of the pipe or pressure vessel, a plurality of blocks slidably mounted adjacent the periphery of the door and movable from a position at least substantially wholly within the said periphery to a position in which a part of each block protrudes beyond the periphery for engagement with the said body, the said parts in the blocks together forming a protrusion extending substantially entirely round the periphery of the door, and means for moving the blocks from the withdrawn to the protruding position.