Page 21 - Impiantistica Industriale

may cause side reactions, modify the extension of
the two phase region and have an effect increasing
the saturation pressure which is the driving force in
the running shear fracture of a pipeline transporting
liquid /supercritical CO .
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The R&D gap analysis on the running ductile frac-
ture for subsea lines transporting CO mixtures has
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led to the development of an internal guideline to
design new or to verify repurposed lines and to
identify that it would be desirable to reinforce some
assumptions with experimental burst tests for me-
Picture 8 – Saipem Pipe Laying Vessel Castorone dium diameters subsea lines possibly in a new JIP
on this specific subject.
In parallel Saipem is conducting, in RINA-CSM la-
boratories in Rome and Cosenza, an experimental Safety Aspects and Loss
test campaign to qualify a typical material for long Prevention
and high-pressure pipelines and the girth welds
performed onboard Saipem Vessels. New tests are Safety aspects of Hydrogen, H /NG and CO pi-
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also planned in 2023 for coating and field joint co- pelines are of paramount importance. The Major
atings applied to offshore pipelines. Accidental Hazards associated to H /NG and CO
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Saipem is part of EPRG (European Pipeline Rese- offshore pipeline systems are related to loss of con-
arch Group) where the Hydrogen Topic group is tainment events.
working at an important test campaign in H en- In case of a subsea release from an offshore CO
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vironment. pipeline system, an underwater plume is produced
ASME B31.12, currently the main reference code which can impact the local flora and fauna due to
on Hydrogen piping and pipelines, could be com- pH changing close to plume. If the plume reaches
plemented and modified with additional considera- the sea surface, it produces
tions on material and welding properties in gaseous a bubble zone which can af-
hydrogen environment and for offshore pipeline de- fect passing ships impacting Saipem is part of EPRG
sign. In this regard, Saipem is represented in ASME on their buoyancy. Through (European Pipeline Research
Europe International Working Group B31.12 and the bubble zone, the CO gas “Group) where the Hydrogen
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will work together with the other members to com- disperses in atmosphere pro-
plement the code as required by the new energy ducing a cloud of asphyxiant/ Topic group is working at an
transport scenarios. toxic gas: pure CO is an important test campaign in
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asphyxiant gas and the con- H environment
CO Pipelines Offshore tent of impurities from CCS 2
process, such as H S, CO ,
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can increase its toxicity. The cloud of asphyxiant/
For submarine pipelines, the effort by Saipem is fo- toxic gas can affect people on board of passing
cused on the understanding of the thermodynamic ships, or in the offshore installations or at shore
behavior of CO streams with impurities, the related causing injury from minor to severe and potentially
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flow assurance issues (phase control), the running loss of life depending on toxic substances concen-
ductile fracture phenomena, the readiness of in-line tration and exposure time.
equipment and the safety aspects relevant to the In case of a subsea release from a hydrogen or
development of a risk assessment methodology for H /NG pipeline, an underwater plume is produced
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CO Leakages. as well. The impact for underwater environment is
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The DNV-RP-F104 for CO pipelines is already alig- less severe than CO case while the atmospheric
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ned with the failure modes approach and advanced dispersion can produce an environmental impact
in terms of specific requirements such as dealing from moderate to high or very high depending on
with impurities. It has also a tested approach for the inventory released. In addition, since Hydrogen
specific failures mode such as the running ductile is a flammable gas, easy to ignite, the likelihood of
fracture in the 2021 edition with the contribution of a flash fire or explosion is higher than for natural
the CO2SafeArrest Joint industry project. gas case. The thermal effects of a flash fire due
The effort by Saipem is focused on the areas re- to hydrogen ignition as well as overpressure due
levant to offshore application still requiring further to vapor cloud explosion produce harm to people
advancement such as the validation of tools for cal- from severe to loss of life.
culating the thermodynamic behavior of CO mixtu- To reduce risks of pipeline system operation at as
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res and in particular the decompression curves in low as reasonably practicable levels, a formal and
case of pipeline ruptures (for those cases not fully rigorous risk assessment process is required from
covered by the current state of art). The work done the early stage of engineering phase. In particu-
on CO was focused mostly on predictive models lar, the risk assessment process can allow a de-
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for CO with impurities with the objective to guaran- sign which considers the safety and environmental
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tee operating flexibility and safety. In fact impurities aspects and identifies the proper risk reduction

Impiantistica Italiana - Maggio-Giugno 2023 17