AD ALTA
JOURNAL OF INTERDISCIPLINARY RESEARCH
refrigerated, liquefied gases with the operating
temperatures between 0°C and – 165°C;

EN 1474: „Design and testing of LNG loading/unloading
arms“;

EN 13645: „Design of onshore installations with a storage
capacity between 5 tones and 200 tones “(CEN).
According to ADN (European Agreement Concerning the
International Carriage of Dangerous Goods by Inland
Waterways) maximum volume of the tank type G1 designed for
the transportation of LNG by inland waterways is 380 m
3
. Due
to the expected size of vessel (in case of pushing convoys is a
type DE IIb) is the maximum volume at 350 m
3
(European
Commission – SEVESO III).
3 Research questions and the focus of the study
The paper focuses primarily on the assessment of two research
questions: (1) what are complying with the design parameters of
LNG tanks for the transport and storage of LNG for inland
vessels and inland LNG terminals? (2) What are the basic
strength parameters, which must comply with tanks? Design of
suitable reservoirs depends on several factors (purpose, ship size,
the parameters of the waterway, LNG terminal capacity etc.).
Therefore, is necessary within the solving of the research
questions consider mentioned aspects.
4 The basic design parameters of LNG tanks
Due to the physical properties of LNG, its transport and long-
term storage must necessarily bring a wide range of mainly
safety and technical issues. A significant role plays here also the
economical and the environmental aspects. To solving all these
aspects have been expended great resources. It brought a wide
range of technical solutions in storage technology useful not
only in inland terminals but also for vehicles (Skrucany et al,
2015).
For vessels transporting liquefied natural gas, current legislation
allows to use 4 types of tanks:

membranes tanks,

independent self-supporting tanks:

type A,

type B,

type C.
Figure 1 Classification of LNG Carriers according IMO (Source: GIIGNL)
LNG fuel tanks must comply the criteria of Independent self-
supporting tanks (type A, B, or C) according to the IMO and
ADN legislation (Figure 1). Specifically, the fuel tanks of inland
vessels must comply with type C.
From a technical and operational point of view using of
reservoirs "C" provides several benefits:

IGC (The International Code for the Construction and
Equipment of Ships Carrying Liquefied Gases in Bulk)
does not required secondary barrier for this type of tank,

Small and medium sized tanks can be designed with
vacuum insulation, which saves insulating material and it
increases the efficiency of the insulation,

Simple installation (for the storage of the tanks are
sufficient two suitable shaped supports,

Ability to design the tanks for high pressure, which is good
for long-term storage and solving problems with
evaporation.
From a structural point of view these are mostly double-skin
pressure tanks cylindrical shape with an arched bottom. The
inner tank is made of austenitic stainless steel or 9% nickel steel.
The outer container, which acts as a secondary barrier can be
made from either stainless steel or carbon steel. The wall
thickness of the inner and outer container is at least 3 mm. The
space between them is isolated by a combination of Perl /
vacuum or Multi-Layer Insulation (MLI) / vacuum. The tank is
equipped with fittings for filling, pressure regulators, taking into
LNG heat exchanger, measuring level and pressure (Hoffman,
2016). Standard tanks are designed for the pressure of 1.6 MPa.
The real operating pressure depends on the needs of the engine
and the injection device fluctuates from 0.3 to 1 MPa (Buil,
2013). LNG technology differs from CNG technology only in
tanks and evaporation, other technological elements are in both
same. The design must meet the requirements of the IMO IGC
"International Code for the Construction and Equipment of Ships
designed for liquefied gas" and EN 13458-2 "for cryogenic
vessels (IMO).
5 Assessment of strength characteristics of LNG tanks
Solution of strength characteristics of LNG tanks was carried out
by finite element method (FEM), which were evaluated using the
HMH stress hypothesis, i.e. hypothesis of maximum specific
deformation energy required to change shape. This hypothesis
gives the most accurate value and is most commonly used. It is
used in the computation software where reduced stress by HMH
strength hypothesis is called Von Misses stress. It is suitable for
ductile materials. The criterion of dangerous condition is
maximum specific strain energy required to change shape
í µí¼†
í µí±¡ í µí±ší µí±Ží µí±¥
.
Strength HMH hypothesis assumes that a dangerous condition
occurs when the specific strain energy for changing the shape of
the stress state exceeds specific strain energy to change the shape
of rectilinear con stress state, which results in failure. Requires
the fulfilment of inequality:
í µí¼†
í µí±¡ í µí±ší µí±Ží µí±¥
â‰¤í µí¼†
í µí°·
,
(1)
IMO Classification
of LNG Carriers
Independent self
supporting tanks
Type A
P
0
≦ 70 kPa
Full secondary
barrier
Type B
P
0
≦ 70 kPa
Partial secondary barrier
MOSS
Spherical
Al or 9 % Ni
SPB
Prismatic
Al or SUS 304
Type C
P
0
≧ 200 kPa
No secondary barrier
Non - self
supporting tanks
Membranes
P
0
≦ 70 kPa
Full secondary
barrier
GTT NO96
INVAR
INVAR
GTT MK III
SUS 304 L
Composite
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