Chemical Engineering August 2021 - 37

TABLE 1. CODES, STANDARDS AND REGULATIONS RELATED TO HYDROGEN PIPING
Codes and Standards
Titles
29 CFR 1910.103
API 940
API 941
ASME B31.3
ASME B31.12
ASTM B-849
ASTM B-850
ASTM F-1459
ASTM F-1624
ASTM G-142
ASTM STP-962
CGA G-5
CGA G-5.4
CGA G-5.5
Hydrogen
Steel Deterioration in Hydrogen
Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum
Refineries and Petrochemical Plants
Process Piping
Hydrogen Piping and Pipelines
Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk
of Hydrogen Embrittlement
Standard Guide for Post-Coating Treatment of Iron or Steel For Reducing
Risk of Hydrogen Embrittlement
Test Method for Determination of the Susceptibility of Metallic Materials to
Gaseous Hydrogen Embrittlement
Standard Test Method for Measurement of Hydrogen Embrittlement Threshold
in Steel by the Incremental Step Loading Technique
Standard Test Method for Determination of Susceptibility of Metals to Embrittlement
in Hydrogen Containing Environments at High Pressure, High
Temperature, or Both
Hydrogen Embrittlement: Prevention and Control
Hydrogen
Standard for Piping at Consumer Locations
Hydrogen Vent Systems
NASA Glenn Safety Manual Chapter 6 - Hydrogen
NFPA 55
oline vapor. This means that in an
outside installation, H2 gas will rapidly
rise and disperse, mitigating any
evidence there is even a leak. But
this can be a double-edged sword.
If welding should be done on an outside
installation above or downwind
in close proximity of a H2 leak without
first performing a leak detection
survey prior to welding, there could
be a detonation. In an enclosed facility,
the H2 gas will rise and accumulate
from the ceiling down - a circumstance
that allows it to build to
a large volume before increasing its
chances of coming into contact with
an ignition source near the floor level.
Autoignition. Autoignition is the
phenomenon in which a mixture
of gases or vapors ignites spontaneously
with no external ignition
source. It is also referred to as " autogenous
ignition " or " spontaneous
ignition. " Autoignition is dependent
upon temperature, not pressure.
The autoignition temperature is the
lowest temperature at which a fuel,
in contact with air or an oxidizer, will
self-heat to ignition without an external
ignition source. The autoignition
temperature for a monopropellant is
the temperature at which it will selfCompressed
Gases and Cryogenic Fluids Code
heat to ignition
in the absence
of an oxidizer.
The autoignition
temperature
of gaseous
H2 in air
is 585°C.
The ignition
energy is the
amount of energy
needed
to initiate
flame propagation
through
a combustible
mixture. The
minimum ignition
energy
is the minimum
energy
required for
the ignition
of a particular
flammable
mixture at a
specified temperature
and
pressure. Minimum
spark
ignition energy
for gaseous
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
OTHER STATES OF H2
As mentioned in the beginning, this article
focuses on the distribution of gaseous H2.
Nevertheless, it is worth taking a brief look
at two other states of H2 - liquid and
slush H2.
H2 in its liquid state is used overwhelmingly
for three things: rocket fuel, as a
means to economically transport H2, and
as a means to economically store H2 in
large volumes for gaseous H2 distribution.
Slush H2 is H2 that is held at what is referred
to as the fluid's triple point. The triple
point in thermodynamics is the point of
specific pressure and temperature at which
a substance can be held at its coincident
gaseous, liquid and solid states. With H2,
this is achieved at 13.81K (-434.81ºF) at a
pressure of 7.042 kPa (1.02 psi). This coincident
state of H2 resembles a slush. Slush
H2 is currently under consideration as a replacement
aerospace fuel for liquid H2.
Because these two states of hydrogen
(liquid and slush) are relegated more to
transport, storage and aerospace fuel,
they are beyond the subject matter of gaseous
H2 distribution and deserve their own
literary space on the topics of H2 transport,
storage, and the more exotic aerospace
fuel.
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AUGUST 2021
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Chemical Engineering August 2021

Table of Contents for the Digital Edition of Chemical Engineering August 2021
