Disclosed is a seal assembly for dividing an annular space defined between an inner and an outer pipe in a double-walled pipeline. The seal assembly comprises an annular member (1) adapted to fit within the annular space and at least one longitudinal conveying means (6) passing through the annular member (1), wherein said longitudinal conveying means (6) communicates with the annular space on either side of the seal assembly. The longitudinal conveying means may comprise for example electrical conducting means or an optical fibre.
