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

conduct experimental tests for the qualification of
Saipem offshore pipeline systems for the new transport
conditions and scenarios.

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

They are both gases at standard conditions, however
CO in the typical transport conditions of a gas
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pipeline, can be very close to a phase change from
gas to liquid or to a supercritical state depending on
the selected operating pressure and temperature.

Saipem Offshore Engineering Team Picture 4 – Hydrogen and CO Transport Scenario and Key Properties Highlights
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promoted first and then joined the
JIP H2Pipe by DNV
to write a Guideline on design,
construction and operation of
hydrogen pipelines that supplement
the standard DNV-ST-F101 on
submarine pipeline systems

This behaviour is magnified if the CO includes
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impurities because it behaves like a mixture. Picture
5 groups and directly compares in one graph the
phase envelopes for pure methane, a typical natural
gas composition, pure CO and some CO mixtures Picture 5 – CO phase diagram (pure and with impurities) vs. pure methane and
2 2 2
making it clear how CO liquid, supercritical or natural gas phase diagram (from DNV-RP-F-104, 2021)
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2-phases protrude in the typical transport region for
gas pipelines. It is to be noted that exceeding the has a very low energy density which is a drawback as
critical point CO has the density of a liquid and the it is transported via pipeline in gaseous form, even if
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viscosity of a gas which is an advantage from a compressed. Another peculiar aspect of Hydrogen is
transport point of view. its ability to migrate into the structure of other
If CO is 1.5 heavier than air, Hydrogen is much lighter. materials. In metals as well, causing the deterioration
2
It has the highest energy content per unit mass, so, of some properties and this is generally referred to as
much more than the most common fuels, however it material embrittlement.

IndustrIal Plants - May 2023
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