Custody transfer systemfor LNG carriers
2
Reliable tank gaugingfor LNG carriers
Thousands of tons of liquefied natural gas rush through the pipes
into the tanks of your LNG carrier. Raising your eyes, you look
beyond the dazzling lights of the tank terminal into the dark sand
dunes behind.
Concentrating on the levels, temperatures and pressures in the tanks,
you feel confident that the Saab TankRadar system is giving you
instant, accurate, reliable information about your cargo.
This brochure tells you how your LNG carrier operation can become
more efficient and profitable with the Saab TankRadar custody
transfer system.
3The Saab TankRadar custody transfer system can be installed on LNG carriers with
either spherical or membrane type tanks.
4All values from the Saab TankRadar system are available on the Work Stations. The Work Stations are
based on PCs with a fast real time operating system. The system is operated using a light pen.
5
In control of your cargo
The feeling of being in control and of
being able to rely on your equipment is
important to all professionals in tanker
operations. But, when your job is to
handle liquefied natural gas in a safe,
efficient way, this becomes significantly
important.
With the Saab TankRadar custody trans-
fer system for LNG carriers, you have
reliable information so that you can safely
control your cargo operation.
No downtime due to repairsinside the tanks
With Saab TankRadar we introduce a
whole new way of measuring the cargo
in LNG carriers. With the tank gauges on
top of the tanks, there are no parts inside
the tanks that can break down or degrade.
Knowing how much unscheduled down-
time costs, your Saab TankRadar system
will soon pay off with its reliable opera-
tion.
Accurate and reliable radarmeasurement
We have put a lot of effort into making a
tank gauge that measures with high
accuracy even under the most demand-
ing circumstances. You receive accurate,
reliable figures during all stages of
loading, transporting or discharging.
The temperature and pressure sensors
are connected to the radar tank gauges,
so that the Saab TankRadar system always
gives you the complete picture of the
cargo in your LNG tanks.
6
Certified custodytransfer system
The costs of transporting gas and the cost
of the cargo places a lot of importance on
the custody transfer system on any LNG
carrier. The custody transfer system must
generate detailed and indisputable cargo
reports, based on accurate measurements
and calculations.
Saab TankRadar is a completecustody transfer system for
LNG carriers.
The Saab TankRadar gauge measures
ullage, temperature and pressure. From
these values the Work Station calculates
for example, levels, vapor and liquid
average temperatures and cargo volumes
at average liquid temperature. It uses
certified tank tables and corrects for
parameters, such as thermal expansion of
the tank and the still pipe, the propaga-
tion speed of the radar waves in the
vapor space, trim and heel.
Accuracy certified by NKKK
NKKK, the Japanese sworn surveyor, has
certified the Saab TankRadar system for
custody transfer. Saab TankRadar ’s
accuracy of ± 5 mm meets the requirement
of LNG exporters and importers. And all
the major classification societies have type
approved the Saab TankRadar system.
Verification at any time
Whenever company procedures or mea-
surement standards require verification,
the crew can easily verify the performance
of any of the Saab TankRadar gauges.
They just set it to measure the distance to
a verification pin inside the still pipe. This
pin is “invisible” to the tank gauge in nor-
mal operation.
Furthermore, the performance of the Saab
TankRadar gauges can be checked against
verifiers set to correspond to 20% and 80%
of the tank’s level.
7Detailed and indisputable cargo reports are generated by the Saab TankRadar custody transfer system.
8
Radar is the natural choicefor LNG carriers
Because the temperature sensors are
placed in a thermowell, they can easily be
replaced from outside the tank. Spare
temperature sensors are stored onboard
in the spare parts set.
The still pipe guidesthe radar waves
The electronic box generates and trans-
mits radar waves into the cone antenna.
It provides a smooth transition for the
waves into the still pipe. Because the still
pipe guides the radar waves, very little
signal energy is lost, which results in a
strong echo from the liquid surface.
Saab TankRadar meansno maintenance
No maintenance is required on the Saab
TankRadar system. This means years of
trouble free operation, with highly accu-
rate and reliable results calculated and
presented on the Work Stations.
In a tank that is -160 °C, and may not be
opened for years, you really do not want
to have electrical cabling or moving
mechanical parts. Any failure on such
equipment inside the tank might result in
having to warm the tank, inert it, gasfree
it, enter into it to repair the failed equip-
ment, inert, purge and cool down the tank.
No LNG carrier operator wants to do
these time-consuming tasks.
This is where radar tank gauging, with
only the still pipe and the cone antenna
inside the tank, comes into the picture. No
equipment inside the tank can break
down or degrade in operation. The safety
risk involved when gasfreeing is elimi-
nated and no harmful gases have to be
released to the environment.
The electronic box of the Saab TankRadar
gauge is placed outside the tank. In the
unlikely event of a failure, the crew can
easily replace it with a certified spare. The
tank gauge can be serviced, tested and
back in operation in less than an hour.
9The Saab TankRadar gauges are installed on top of your tanks.
No equipment inside the tank can break down or degrade in operation.
10
Pressure seal
Ball valve
Antenna cone
Still pipe
Electronic box
Pressure sensor
Protective hose
Thermowell
Temperature sensor
11The Saab TankRadar gauge is installed on top of a still pipe. The temperature sensors are installed in a thermowell.This means that you can easily replace the electronic box and the temperature sensors, with the tank in operation.
12
Convenient installation
Because the only parts inside the tank
are the still pipe, cone antenna and
thermowell, the installation of the Saab
TankRadar system is very convenient. It
can be installed on newbuildings or be
retrofitted on existing LNG carriers.
Reduced testing at shipyard
We put each Saab TankRadar system and
each tank gauge, including the still pipe,
through a factory acceptance test, that is
also supervised by a sworn surveyor,
before delivery. This minimizes testing at
the shipyard and ensures the best possible
measurement conditions.
We deliver the still pipe in typically six-
meter-long, numbered sections, ready to
be installed into the tank’s pipe tower or
tripod.
The temperature sensors are installed into
a thermowell manufactured by the ship-
yard. After the sensors have been installed
and connected, the thermowell is inerted.
Both the still pipe and the thermowell can
share the same penetration through the
tank dome.
Technical support from designto commissioning
Saab Marine Electronics supports the
shipyard with documentation and tech-
nical support from the design stages to the
commissioning of the system. Together
with each Saab TankRadar system, we also
provide comprehensive and dedicated
documentation that includes all appli-
cable certificates. One of our certified
service engineers assists during the com-
missioning of the system.
13
Electronic box
Antenna cone
Still pipe
Pressure equalization
hole
Verification pin
Protective hose for cables
Tank dome penetration
Thermowell
Temperature sensors
Pipe for inerting the thermowell
The Saab TankRadar system can be installed on newbuildings or retrofitted on existing LNG carriers.Both the still pipe and the thermowell can normally share the same tank penetration.
14
Window Overview Setup Grou p Trend Alarm
Alarm
Saab TankRadarWed Aug 24 20:05:30 1994
Hi.Hi CT 6 Ullage 1,837 (2,000) mAccept BuzzerStop
2...more
Help Exit all
ExitBackCargo System Fore
P
LC8LC7
26 bar
P
LC6LC5
24 bar
P
LC4LC3
20 bar
P
LC2LC1
23 bar
T.avg18.8 C
T=18.6
T=18.7
T=19.1
0.00 m/h
Ullag e1.956 m
CT4
T.avg18.8 C
T=18.6
T=18.7
T=19.1
0.00 m/h
Ullage5.630 m
CT3
T.avg18.8 C
T=18.6
T=18.7
T=19.1
0.00 m/h
Ullage8.502 m
CT2
T.avg18.8 C
T=18.6
T=18.7
T=19.1
0.00 m/h
Ullag e1.559 m
CT1
Window Overview Setup Grou p Trend Alarm
Alarm
Saab TankRadarWed Aug 24 20:05:30 1994
Hi.Hi CT 6 Ullage 1,837 (2,000) mAccept BuzzerStop
2...more
Help Exit all
ExitBackCargo S ystem Fore
P
LC8LC7
26 bar
P
LC6LC5
24 bar
P
LC4LC3
20 bar
P
LC2LC1
23 bar
T.avg18.8 C
T=18.6
T=18.7
T=19.1
0.00 m/h
Ullage1.956 m
CT4
T.avg18.8 C
T=18.6
T=18.7
T=19.1
0.00 m/h
Ullage5.630 m
CT3
T.avg18.8 C
T=18.6
T=18.7
T=19.1
0.00 m/h
Ullage8.502 m
CT2
T.avg18.8 C
T=18.6
T=18.7
T=19.1
0.00 m/h
Ullag e1.559 m
CT1
7 8 9 0
4 5 6
1 2 3
ALARM SYSTEM
MENU SERV
ENTER CLEAR
OK i
1 2 3
LCP LCM LCS LCM LCS LCI
Technical details
Technical specifications for Saab TankRadar
The main parts of the Saab TankRadar
system are:
• The tank gauges that measure ullage,
vapor pressure as well as liquid and
vapor temperature.
• The Level Unit that contains much of
the calculation power for the signal pro-
cessing and the circuits for ensuring the
intrinsic safety. The tank gauges are
connected to the Level Unit. The signal
processors and memory circuits are
doubled for internal redundancy in the
Level Unit.
• The Work Stations that calculate the
cargo volume from tank parameters and
measured values. They also supervise
and warn of any alarms that may occur.
A Work Station consists of a PC that
is type approved for operating in
the marine environment. A printer is
included for printing custody transfer
reports and various logs.
• The Redundancy Box that automatically
switches master Work Station, if the ac-
tive master fails.
Accuracy: ±5 mm
Measurement range: 0-45 m
Gauge operating temperature: -40 to +80 °C (in-tank temperatures can be down to -165 °C)
Max. operating pressure: 8 barabs
Intrinsic safety of gauge: EEx ia IIC T4
Temperature measurement range: -165 to +55 °C
Temperature measurement accuracy (includingsensor): ±0.2 °C for cargo temperatures -165 to-145 °C, ±1.5 °C for cargo temperatures -145 to+50 °C
Number of temperature sensors: Typically 5active sensors per tank
Pressure measurement range: 0.8 to 1.4 barabs
Pressure measurement accuracy: ±1% of full scale
Still pipe (Saab or yard supply): 114.3 x 3.65 mm instainless steel or aluminum
Thermowell (yard supply): Max. outer Ø 32 mm
Tank penetration (yard supply): Still pipe only:Min. inner Ø 154 mm, recommended 250 mmPipe and thermowell: Min. inner Ø 300 mm
Work Station Work Station Level Unit
RadarTank
Gauge
Still pipeand
thermowell
RedundancyBox I/O Box
Interface to othercomputers
Printer
15
Saab Marine Electronics –Pioneers in radar tank gauging
Tank gauging with radar is not a new
technology for Saab Marine Electronics.
We have developed, produced and mar-
keted radar tank gauging systems for
tankers since 1975. We have released three
generations of Saab TankRadar systems
for tankers – each new generation bring-
ing new customer benefits. Today, more
than 1 100 tankers are sailing with Saab
TankRadar systems.
In the early 1980s Saab Marine Electron-
ics released Saab TankRadar for onshore
tanks. Many of the same features that
brought success on the tanker market,
appealed to the instrument engineers at
refineries, tank terminals, chemical plants
and other industries. More than 500 LPG
onshore tanks are equipped with Saab
TankRadar and it has been successfully
installed on LNG storage tanks in Japan.
More than 35 000 Saab TankRadar gauges
have been installed on both tankers and
onshore tanks.
Certified quality andenvironmental systems
In 1992, Saab Marine Electronics was the
first supplier of tank gauging equipment
to be certified according to ISO 9001. In
1997 we were again first to be certified
according to ISO 14001 for our environ-
mental management system.
LNG/C Khannur with Saab TankRadar onboard.
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