CSA EXP 276.1:2015 pdf download.Design requirements for marine structures associated with LNG facilities
4.3.3 Geotechnical
Guidance on geotechnical site characterization, analysis, and evaluation of seismic and geological hazards, including seismic hazard assessments, are included in Clause 6 of this Document. Clause 6 also provides considerations in respect of design for tsunamis.
4.3.4 Climate change and sea level rise
During planning and design of LNG marine facilities, designers should take account of the fact that climate change is expected to cause sea level rise and changes in storm intensity and direction (potentially affecting coastal surge/wave and pluvial/fluvial events). Potential impacts are very region-specific and local guidance should be sought where available. The Inter-Governmental Panel on Climate Change (IPCC) provides an updated assessment every five to seven years, on which many regional authorities base local guidance. There is considerable uncertainty over the likely timing of the melting of the Greenland Ice Sheet and the West Antarctic Ice Sheet, which are significant contributors to future sea-level rise.
Changes in mean sea-level relative to land levels over the design working life should be taken into account by the designer. Sea-level rise is principally caused by thermal expansion of the water and melt of mountain glaciers/land-based ice increasing its volume (eustatic rise), and tectonic and post-glacial movements of land (isostatic rise). Predictions for relative mean sea-level rise in a particular region therefore vary from the global average due to geographical variations in temperature and salinity and geological processes affecting vertical land movement.
The designer should take the contributing factors into account when reviewing and selecting appropriate values to be adopted in the assessment of actions and environmental conditions affecting the structure.
4.5.2.2 CAN/CSA-ISO standards
The CAN/CSA-ISO 19900 series of Standards (see Table 1) were developed to provide general principles in accordance with international ISO standards for the design and assessment of all types of offshore oil and gas structures. The design principles provide guidance for the entire facility life cycle including fabrication, transportation and installation, use of the structure during its service life, and ultimate decommissioning.
These standards have some applicability to LNG marine facilities, but they do not in themselves cover all applicable load cases and combinations for nearshore LNG marine facilities. If these codes are used, the designer shall develop additional load cases and combinations as applicable.
CAN/CSA-Z19902 provides methodologies to assess hydrodynamic loads, strength verification, and specific detailing/design information for tubular steel piles and jacket-type structures and may be applied when appropriate for design and detailing of comparable structural elements forming part of LNG marine facilities.
Clause 6.6 of CAN/CSA-Z19902 provides exposure levels based on occupancy (life safety) and the consequence of failure of hydrocarbon release. The location, operational characteristics, and hazards of an LNG marine facility do not directly correspond to the life safety and consequence categories for offshore structures. In the absence of any other assessment, it may be assumed that an LNG marine facility is S2 (manned evacuated) and C2 (medium consequence), resulting in an exposure level L2.CSA EXP 276.1 pdf download.