| 摘要 |
<p>A vent assembly for venting of plastics lined pipelines is inserted through the wall of a steel pipeline (2). The vent assembly (1) has a main body (3) having a small through-hole (4). A porous element (5) fits in a recess (6) in the main body (3) and a non return valve (7) is held in place by a retaining cap (10). The valve assembly (1) fits flush with the inner surface (11) of the pipeline (2). A micro annulus (13) exists between the pipeline (2) and the liner (12). In use, the pipeline (2) is typically used for hydrocarbons and the plastics liner (12) is permeable to the gas content in the hydrocarbon. Consequently a small quantity of gas finds its way into the micro annulus (13) from where it can escape through a nearby vent assembly (1).</p> |
