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Table 2 – Summary of Study Cases Data used within the R&D Research Program by Saipem

neering disciplines involved in pipeline design, to
develop recommendations and guidelines or pro-
cedures and fit for purpose design tools, to con-
solidate a network of suppliers ready for the new
scenarios, to elaborate and conduct experimental
tests for the qualification of Saipem offshore pipe-
line systems for the new transport conditions and
scenarios.

Know your partners:
Hydrogen and CO
2
The two fluids have some peculiar properties quite
relevant to pipeline transport (Picture 4).

They are both gases at standard conditions, ho-
wever CO in the typical transport conditions of a
2
gas pipeline, can be very close to a phase chan-
ge from gas to liquid or to a supercritical state
depending on the selected operating pressure Picture 4 – Hydrogen and CO Transport Scenario and Key Properties Highlights
2
and temperature. This behaviour is magnified if
the CO includes impurities because it behaves
2
like a mixture. Picture 5 groups and directly com-
pares in one graph the phase envelopes for pure
methane, a typical natural gas composition, pure
CO and some CO mixtures making it clear how
2
2
CO liquid, supercritical or 2-phases protrude in
2
the typical transport region for gas pipelines. It
is to be noted that exceeding the critical point
CO has the density of a liquid and the viscosity
2
of a gas which is an advantage from a transport
point of view.
Saipem Offshore Engineering
Team promoted first and then
“joined the JIP H2Pipe by DNV Picture 5 – CO phase diagram (pure and with impurities) vs. pure methane and natural gas
2
to write a Guideline on design, phase diagram (from DNV-RP-F-104, 2021)
construction and operation
of hydrogen pipelines that If CO is 1.5 heavier than air, Hydrogen is much
2
supplement the standard DNV- lighter. It has the highest energy content per unit
mass, so, much more than the most common
ST-F101 on submarine pipeline fuels, however it has a very low energy density
systems which is a drawback as it is transported via pipeli-
ne in gaseous form, even if compressed. Another

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