GS48A

Long shelf life for
original LNGC kit
The durability of the cargo-handling equipment on
the early LNG carriers highlights the sound engineering
principles on which the suppliers based their designs
In discussions on the various early
LNG carrier designs, the emphasis
has always been on the relative
merits of the rival cargo containment
systems. Engineering components like
cargo pumps, compressors, valves,
gauges and control systems, so vital to
the safe and effective operation of the
vessels, rarely get a mention.
Many of the essential pieces of cargohandling
equipment developed for the
early LNG carriers enjoyed universal
applicability, irrespective of the ship’s
chosen containment system. And many
of these pioneering equipment items
are still around today, albeit in scaledup
versions. Their longevity bears
testimony to the sound engineering
principles and innovative technology
on which the design of the original
equipment was based.
One good example is the
submerged electric motor pump
(SEMP). Without these sophisticated
cargo pumps, with the ability of their
motors to operate within the liquid
cargo, the progress from original
experimental LNG vessels to the
modern ships of the 266,000m 3 Q-max
size would not have been possible.
The original JC Carter cryogenic
centrifugal pump was developed in
1947 in support of the US government’s
early rocket programmes. The pumps
were used to feed liquefied gas fuel
to the rocket engines. James Coolidge
Carter conceived the idea for a SEMP
for liquefied gas service at his factory in
Costa Mesa, California in 1958.
SEMPs have a major safety
advantage over their external motor
counterparts in that there is no need
for a shaft to penetrate the tank, thus
eliminating mechanical seals. Another
advantage of integrating the pump and
motor into a single unit with a common
shaft is that coupling and alignment
issues are removed. As hydrocarbons are
dielectric fluids, electrical cables and the
motor itself can be safely surrounded
by LNG.
Deepwell pumps had been fitted
on Methane Pioneer for its historic trial
voyages in 1959 but such units proved
not to be ideal in LNG service as the
temperature differential between the
tank and the external atmosphere had a
tendency to cause the shaft to bind.
The first shipboard JC Carter SEMPs
were installed in one of the three cargo
tanks on the experimental 640m 3 LNG
vessel Beauvais, the conversion of which
was completed in February 1962. The
tests proved to be satisfactory and a
shipset of nine JC Carter SEMPs was
ordered for both Methane Princess and
Methane Progress. Each cargo tank on
the vessels was fitted with a single
pump with a capacity of 205 m 3 /hour. A
secondary gas lift pumping system was
the pioneers|LNG Shipping at 50
fitted on the deck. Mr Carter himself
was amongst the distinguished guests
present at Canvey Island in October
1964 to welcome the arrival of Methane
Princess from Algeria with the first
commercial LNG cargo.
Early on in the evolution of LNGC
design it was decided that two cargo
pumps per tank offered the optimum
arrangement for timely and efficient
cargo discharges. JC Carter was to
become the market leader for SEMPs for
LNG carriers over the next two decades.
Honeywell was another US supplier
of equipment to Methane Princess and
Methane Progress. A Honeywell 320
point data logger was installed in each
vessel’s main cargo control room for
recording temperatures from the cargo
tank surfaces, the insulation and the
hull structure. The data recorded was
transferred to a strip printout sheet for
onboard use and a punched tape for
computer analysis ashore.
Foster Wheeler provided two of its
ESD II main boilers for each of the steam
turbine-driven Methane Princess and
Methane Progress. The units were the first
to utilise cargo boil-off gas (BOG) on an
LNG carrier, and the combustion system
was designed to burn fuel oil, methane
BOG or a combination of both. Foster
More often than not, modern equipment is simply a scaled-up version of the
technologies first proven on the early LNG carriers
A SIGTTO/GIIGNL commemorative issue LNG shipping at 50 I 43