Historically, the marine systems on a Spar (ballasting, de-watering, ventilation, access, etc.) are relatively simple. However, attracted to the operational value of having large volumes of storage, particularly for flow assurance of the subsea wells and flowlines during shut-down conditions, the Gulfstar hull design criteria included the capabilities to store, inside the hull, 10,000 bbl of dead oil, 1,000 bbl each of diesel and methanol, all in integral carbon steel tanks, plus 2,400 bbl of subsea chemical in 18 individual stainless steel, vertical pressure vessels in both 100 and 200 bbl sizes. This took the Spar hull from being a relatively ‘unsophisticated’ hull to something much more complex.

The paper traces all the key process support and marine systems from their humble beginnings to their final form with all the Regulatory inputs and requirements which, in hindsight, turned out to be almost ‘a bridge too far.’ After a short description of the systems with unique features and the regulations and design challenges behind them, the paper focuses on recommended changes for future projects, in addition to the obvious idea of radically simplifying those systems.

As marine systems get more complex and projects try to introduce lower weight/lower cost/safer solutions ideas to optimize them, the existing Rules and Regulations can impede attempts to innovate in this area. As part of the lessons learned discussion, the paper speaks to the efficacy of risk-based design as compared to the traditional proscriptive/rules-based design approach as a way to accelerate innovation without compromising safety and operability.

The information and results presented in this paper are applicable to engineers, class societies and regulators when trying to introduce more efficient process support and marine systems.

This content is only available via PDF.
You can access this article if you purchase or spend a download.