Patent ID: 6939083
Filing Date: 2005-09-06
Classification: B23K,F16L

Abstract:
1. A method of laying pipeline on a seabed, in which the pipeline comprises inner pipe lengths connected together and outer pipe lengths connected together around the inner pipe lengths and in which the outer pipe lengths are joined to the pipeline as it is laid by a welding process involving the following steps for welding the end of a length of a first outer pipe to the end of a length of a second outer pipe: fitting an annular member in the end of the first outer pipe with a first axial part of the member within the first outer pipe and a second flange part of the member projecting radially outwardly beyond the inside of the first outer pipe and terminating radially inwardly of the outside of the first outer pipe; bringing the end of the second outer pipe into a position substantially axially aligned with and confronting the end of the first outer pipe, with the second flange part of the annular member interposed between the confronting ends of the first and second outer pipes, the second flange part projecting radially outwardly beyond the inside of the second outer pipe and terminating radially inwardly of the outside of the second outer pipe; welding the confronting ends of the first and second outer pipes together, the second flange part of the annular member providing some of the welding material; and in which the first axial part of the annular member includes a portion of reduced external diameter adjacent to the flange part, whereby, when the annular member is fitted in the end of the first outer pipe, an annular cavity is formed between the annular member and the inside of the end of the first outer pipe, the cavity being defined by the inside of the first outer pipe, the outside of the reduced external diameter portion of the first axial part and the flange part.