Pressurising a pipeline during laying on seabed, etc. - to compensate for hydrostatic external pressure and pipe laying compressive stresses

摘要

Interior of a pipeline is placed under pressure by isolating in it a chamber selectively closed by sealed joints, introducing a fluid under pressure into this chamber to establish a predetermined pressure, enlarging the chamber at the same time as the pipeline is extended for the whole pipe construction period and maintaining the pressure inside the chamber at a predetermined level during the enlargement of the chamber continuing this for the whole pipeline construction period. Process provides a convenient way of preventing crushing of pipelines under high hydrostatic pressure e.g. when laying large diameter pipelines in deep water, as well as compensating for compressive stresses arising in the suspended part of the pipeline during laying.