Pipeline bundles are towed to site between towhead manifold structures which are designed to contain all the manifold valve-work and control equipment. The towhead is a space frame that not only supports and protects the on-board equipment during service but also allows the attachment of temporary buoyancy units that are necessary for the towing and controlled ballasting operations during installation.
Pre-installed equipment within the towhead space-frame must be operable following the bundle on-shore transportation, launch, offshore tow and pile driving operations that are necessary to secure some towheads to the seabed.
The analysis work reported in this paper focuses on pile driving activities and was carried out to demonstrate that forced acceleration of pre-installed equipment, caused by transmission of pile driving energy to the towhead, did not exceed the equipment’s recommended allowable shock limits.
The desired outcome of the analyses was an understanding that equipment pre-installation offered an acceptable design solution for a particular towhead configuration founded on a soft silty clay soil in the North Sea and that this outcome would be applicable to future similar towheads.
