AS NZS 2885.4:2016 Pipelines—Gas and liquid petroleum
The following design and integrity items should be considered in detail during the design and operational phases over and above the standard pipeline engineering considerations:
(a) The preservation of the natural and cultural environment should be an integral component in the development of the shore crossing design and the integrity management thereof.
(b) The shore crossing design should consider all environmental loads which may be distinctly different in shore crossing zones compared to other section of the pipeline route, including, but not necessarily limited to, hydrodynamic loads, direct and indirect loads and abrasion from geomorphic processes, loads caused by differential settlement of structures onto which the pipeline is fixed or into which it is housed.
(c) A beach valve may be needed at the shore crossing. The need for a beach valve should be subject to a qualitative risk assessment.
(d) A proven and effective anti-corrosion coating system for the pipeline should be used in this zone with particular emphasis on the coating or an appropriately designed coating protection system’s ability to withstand mechanical damage likely to be sustained before, during or after construction activities and to avoid loss of adhesion during operation.
(e) The corrosion management and cathodic protection systems in the shore crossing zone should be designed to protect the pipeline against the aggressive exposure and environment in this zone, which includes repeated wetting and drying cycles.
NOTE: Furthermore, it is common that the marine environment at a shore crossing is more severe than more distant open seawater in terms of higher temperatures and higher levels of biological activity.
(f) The interface of the onshore and offshore cathodic protection systems should be designed to avoid current drain from one system to the other and the potential passivation of sacrificial anodes.
(g) The inclusion of a tunnel or casing pipe in the shore crossing design, in which the pipeline will be housed, requires specific attention regarding its impact on the functionality and operational testing of the cathodic protection system.
(h) External inspection and monitoring of pipelines in the shore crossing zone is a difficult activity to undertake. Nonetheless, an effective and robust inspection and monitoring regime needs to be developed and implemented to ensure pipeline integrity is maintained over the full extent of the shore crossing zone. Such a regime may include cathodic protection readings that take into account the effect of changing resistivity in the wet/dry transition area or intelligent pigging.