| 摘要 |
<p>There are disclosed methods, components and sub-assemblies for use in the construction of multi-conduit pipelines having multiple fluid conduits (160, 170) closely spaced to one another, and shielded by an outer conduit (200) for insulation. Known pipe-in-pipe constructions are not readily adaptable to include more than one conduit within the outer pipe. In the novel construction, a bulkhead sub-assembly (Fig.5(a)) is first provided, comprising a cast bulkhead unit 100, a primary pipe initiation segment and a secondary pipe initiation segment extending from the bulkhead unit alongside and shorter than the primary initiation segment (Fig. 3). The material and dimensions of the initiation segments are such as to permit temporary deflection of one away from the other sufficiently to permit orbital welding of a further secondary pipe segment to the end of the secondary pipe initiation segment. Both primary and secondary conduits (160, 170) and the outer conduit (200) can then be grown section-by- section using conventional welding equipment only.</p> |
