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of each loss of containment event need to be evaluated.
The assessment of the consequences is usually carried
out by means of advanced simulation tools.
Saipem owns an integral model, called POLPLUME for
the simulation of subsea hydrocarbon releases. It was
developed, in the past, in cooperation with “Politecnico
di Milano”, Department of Chemistry, Materials,
Chemical Engineering “G. Natta”, in Italy. Therefore, the
same department has been involved in 2021 to adapt
the model for different type of fluids like CO and
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Hydrogen.
In addition to POLPLUME upgrade works, Saipem
Team developed an internal computational fluid
dynamic model to assess the subsea behavior of
underwater plume for the most complex scenarios of a
CO release (gas and dense phase at various water
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Picture 9 – CFD Plume due to vapor cloud explosion produce harm to people depths).
from a subsea pipeline from severe to loss of life. In summary, the assessment of the consequences of
rupture transporting To reduce risks of pipeline system operation at as low subsea releases can be carried out with an approach
CO at high pressure in as reasonably practicable levels, a formal and rigorous based on integral models for simple cases of subsea
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dense phase
risk assessment process is required from the early loss of containment events or adopting a computational
stage of engineering phase. In particular, the risk fluid dynamic model for more complex cases. The
assessment process can allow a design which integral models present the advantage to be fast and
considers the safety and environmental aspects and suitable for risk assessment of relatively simple cases.
identifies the proper risk reduction measures where The CFD models are useful for complex analysis but
necessary. The risk assessment main steps have been present the disadvantage of being time consuming,
analyzed by Saipem Team to identify the gaps with have high computational cost and they need the
respect to H /CO transport. One gap is in the specific knowledge of CFD specialists.
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identification of hazards and threats of the frequencies The next step is the validation of these models with
of loss of containment events and consists in the poor relevant mid or full-scale experiments on subsea
or totally missing data about offshore CO and H releases of CO or H that do not exist at the moment.
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Pipelines. The other is related to the consequences of Therefore, Saipem joined safe C02 JIP with major oil
loss of containment events and in particular the lack of and gas companies led by SINTEF to validate those
a good number of validation mid or full-scale models based on full-scale tests.
experimental tests for the simulations model of ruptures The full-scale experiments are planned in the next
and underwater gas dispersion. years, and they will be executed at sea and at various
To estimate the frequencies of loss of containment water depths.
events Saipem developed its own methodology. It is In conclusion, Saipem has developed a methodology
valid for all type of steel pipelines, flexible lines, risers, and a path to efficiently carry out Quantitative Risk
and it includes the onshore pipeline connecting Assessment for CO and H /NG offshore pipeline
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sections. The methodology foresees to estimate the systems reducing the uncertainty of the analysis.
loss of containment frequencies starting from the
database of release frequencies for other hydrocarbon
pipelines. It foresees that a team of representative Final Considerations and Way
leaders and specialists of each project discipline (e.g. Forward: the value of R&D in the
corrosion, material selection, pipeline design, flow
assurance, safety) is involved in a brainstorming Industrial Energy Transition

workshop. The purpose of the workshop is to evaluate
the threats related to CO or H transportation for the The energy transition requires that offshore pipeline
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specific project under analysis and to associate a transport is economically convenient and able to
specific penalty factor to the loss of containment provide large capacity and long-distance transport at
frequency coming from the hydrocarbon database. highest HSE standards. The intersection of
The evaluation of penalty factors is based on the technological gaps and needs allowed the identification
severity of consequences of each threat. of the values that an R&D effort could bring.
Once the frequencies of occurrence of CO or H loss Therefore, starting from mechanical design, the effort
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of containment are evaluated, then the consequences has been and will be:

IndustrIal Plants - May 2023
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