| 摘要 |
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.
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