Submarine pipeline
[1] Sizeable pipeline construction projects need to take into account many factors, such as the offshore ecology, geohazards and environmental loading – they are often undertaken by multidisciplinary, international teams.
[5][6] This task begins with a fact-finding exercise, which is a standard desk study that includes a survey of geological maps, bathymetry, fishing charts, aerial and satellite photography, as well as information from navigation authorities.
If it is uneven, the pipeline will include free spans when it connects two high points, leaving the section in between unsupported.
If the soil is not strong enough, the pipeline may sink into it to an extent where inspection, maintenance procedures and prospective tie-ins become difficult to carry out.
At the other extreme, a rocky seabed is expensive to trench and, at high points, abrasion and damage of the pipeline's external coating may occur.
[2] The structure is often shielded against external corrosion by coatings such as bitumastic or epoxy, supplemented by cathodic protection with sacrificial anodes.
The addition of a concrete coating is also useful to compensate for the pipeline's positive buoyancy when it carries lower density substances.
[2][14] In the petroleum industry, where leaks are unacceptable and the pipelines are subject to internal pressures typically in the order of 10 MPa (1500 psi), the segments are joined by full penetration welds.
It is used to test for hydrostatic pressure, to check for dents and crimps on the sidewalls inside the pipe, and to conduct periodic cleaning and minor repairs.
Several systems can be used – for a submarine pipeline, the choice in favor of any one of them is based on the following factors: physical and environmental conditions (e.g. currents, wave regime), availability of equipment and costs, water depth, pipeline length and diameter, constraints tied to the presence of other lines and structures along the route.
The pipeline leaves the vessel at the stern or bow from a supporting structure called a stinger that guides the pipe's downward motion and controls the convex-upward curve (the overbend).
[25] This on-site pipeline assembly approach, referred to as lay-barge construction, is known for its versatility and self-contained nature – despite the high costs associated with this vessel's deployment, it is efficient and requires relatively little external support.
Onshore facilities to assemble the pipeline have inherent advantages: they are not affected by the weather or the sea state and are less expensive than seaborne operations.
[35] A submarine pipeline may be laid inside a trench as a means of safeguarding it against fishing gear (e.g. anchors) and trawling activity.
Stanislav Patin has said that study on the effects of natural gas on underwater ecosystems, fish and other marine organisms has been limited.
Researchers found a cause-effect relationship between mass fish mortality and natural gas leaks after drilling accidents in the Sea of Azov in 1982 and 1985.
[44] This infrastructure contributes to global energy security, as its function is to transport oil, natural gas and other resources over vast distances.
[48] Disruptions to pipeline operations can cause significant economic losses, environmental hazards, and energy shortages for the affected parties, reflecting the need for their sufficient protection to be of high priority.
[49] Key challenges related to critical maritime infrastructure protection are human activity, geographical accessibility, natural hazards, sabotage, maintenance and monitoring and lack of international cooperation.
[50] Earlier debates about critical maritime infrastructure have shifted from emphasis on terrorism and cyber threats toward the increasing frequency and efficacy of hybrid tactics.
[51] The Nord Stream sabotage demonstrates hybrid attacks, which aim to induce significant damage to an adversary while operating in a way that makes detection, attribution and response difficult to enact, blurring the conceptual lines between conflict and peace.
[53] One reason for the increased attention is the growing threat to critical infrastructure on the seabed and the resulting risk to national security.
[56] NATO working to enhance the security of underwater infrastructure to prevent and respond to threats such as organized crime and hybrid attacks like the explosion of the Nord Stream Pipeline.
The third objective is to lead maritime domain awareness such as information collection and exchange among authorities, to manage risks and threats involving improving the collective resilience of the EU and its member states, to enhance civilian and military capabilities and lastly, to educate and train to ensure a high level of specialised education and skills which is largely focused on skills needed to tackle hybrid threats.
[63] The sabotage of the Nord Stream pipeline in 2022 triggered a substantial response, especially among North Sea coastal states.
