SS: Cryogenic Pipelines: Risk Assessment and Technology Qualification Process for Offshore LNG Pipelines

Abstract

The Liquefied Natural Gas (LNG) market is growing significantly and there is considerable demand for LNG plants and terminals. The challenge for these facilities is even greater in view of public opposition, mostly in the US, to the construction of these facilities onshore because of safety, security and environmental concerns. For these reasons, the oil and gas industry is looking offshore to locate LNG facilities. As part of this development, the safe transport of large quantities of LNG from the LNG offshore terminals, Single Point Moorings or offloading platforms to the storage tanks ashore for gas distribution has become a relevant technical issue, and cryogenic subsea pipelines became a crucial emerging technology. Since neither prior in-service experience nor comparable design review history exist for emerging technologies, the acceptability of such novel concepts for classification requires thorough analysis.An improved process to assist the classification of offshore LNG pipelines has been successfully applied by the authors for the review of several subsea cryogenic pipeline designs. A combination of engineering analyses and risk assessments was employed, creating an effective process to review the proposed design against established safety guidelines. The qualitative risk analyses performed were very effective in identifying risk issues and discussing how they could be prevented and/or mitigated. The analysis of proposed subsea cryogenic pipeline designs concluded that they are technically feasible from both safety and functional perspectives and the so-called Approval In Principle was granted to proposed designs.

Embedment depth and uplift capacity of a cryogenic pipeline dynamically laid in a trench

“…Information in regards to the geometric and structural properties of proposed cryogenic pipelines were collected through a literature review (Prescott et al, 2005;Beike et al, 2009;Ballesio et al, 2009;Brown et al, 2009;Prescott & Zhang, 2009;Spitzenberger, 2009) and discussions with relevant industries. Typical diameter, bending stiffness and weight are listed in Table 1.…”