Heerema Marine Contractors (HMC) is entering a new era of pipe laying with the new Deep water Construction Vessel (DCV) Aegir, designed to be able to reel/J-lay pipelines for a broad range of pipe dimension and water depth combinations. On the one side this is governed by equipment/vessel limitations (moonpool size, high top tension capacity, stinger component capabilities) and on the other side limited by pipeline design code (e.g. DNV, API) acceptance criteria for reel-lay and J-lay installation.
This paper outlines the pipelay capabilities of DCV Aegir and details the J-lay (with quad joints) and reel-lay installation analyses performed to aid in the design of the vessel pipelay equipment. DCV Aegir has two modes for J-lay installation, which are light J-lay with friction clamps and heavy J-lay with collar clamps in combination with collars in the pipeline. DCV Aegir reel-lay installation from the pipeline in the tensioners down to the seabed will also be explained.
Light J-lay, heavy J-lay and reel-lay have maximum top tension capacities (related to the equipment) of 600 mT, 2000 mT and 800 mT, respectively. The top tension capacity also depends on pipe OD, coating type and thickness. J-lay and reel-lay installation analyses are performed with the non-linear finite element software package Flexcom from MCS Kenny to determine installation capabilities with respect to pipe OD, wall thickness and water depth combinations. Together with that the pipelay equipment design is validated by pipeline installation analyses.
Shallow and deep water normal pipeline installation for all three pipelay options will be discussed. DCV Aegir pipelay equipment includes a retractable hang off module/stinger for deployment of pipelines. The usage and benefits of the hang off module will be documented. For the J-lay installation modes the procedure for lowering a quad joint is analysed in order to optimise equipment usage. DCV Aegir possesses a high capacity abandonment and recovery system (up to 2000mT). Abandonment and recovery analyses description and design review aspects will be discussed. Finally, the pipeline in-line structure installation analyses, together with design review considerations will be documented.