12 BULKDISTRIBUTOR
Flexitanks
July/August 2016
Putting flexis in the bin
A new flexitank support system could solve the issue of safe shipment while also making it more financially attractive
I
n recent years, numerous solutions have been developed
to address perceived concerns with carrying flexitanks in
ISO containers.
Principally these involve safeguarding the integrity of the container
by preventing sidewall and other damage that can sometimes
happen when a flexitank is improperly installed and secured within
the container.
However, many solutions thus far have run up against the problem
of loading additional costs onto a logistics system whose main
benefit is usually claimed to be a cheaper solution compared with
other bulk liquids transport equipment, such as tank containers.
Whether it is a bund housing the flexitank or other securing
mechanism, the mechanism itself sometimes adds too much cost to
t he total, and/or the payload has to be reduced, making the cost of
shipment uneconomic for the shipper.
The current flexitank market has been estimated at 580,000
shipments a year and growing, with an estimated 428,000
comprising large payloads of 24,000kg or litres, dependent on the
product being carried.
Now, two container industry veterans have designed a flexitank
system that they claim answers many of the safety and economic
issues in flexitank transport.
Brendan McKenna, former CEO and co-owner of Trans Ocean
Distribution Limited before that company was sold to JF Hillebrand,
and Martin Clive-Smith, who has a long history of designing and
patenting innovative container solutions, have together come up
with the FlexiBin S3.
The FlexiBin S3 is a robust all-steel de-mountable tray comprising
cavity wall sections to allow for high-pressure heating tubes and
insulation. Weighing just 825kg, against as much as 2,000kg
for some other systems, the FlexiBin S3 is described as a wellresearched, engineered and proven device that cost-effectively
protects against container damage for all flexitanks carrying
24,000kg of product and higher.
The units are easy to position in a container and easy to stack using
simple lifting frames designed by CSM.
The ability to allow for the safe carriage of payloads above the
industry ‘standard’ of 24,000kg is a particular benefit claimed by the
developers, who have formed a new company, Clive-Smith McKenna
Ltd (CSM), to market the system, as well as designing other
container solutions.
Some other carrying systems, says CSM, means payloads must be
limited, even down to 21,000kg. However, the FlexiBin S3 allows the
container to carry not just the 24,000kg normally associated with a
standard flexitank fitting; as much as 27,000kg can be carried
without additional risk to the container’s integrity.
In short, this means up to 12.5 percent additional payload, or one
less container per eight containers shipped, a potential 12.5 percent
savings in cost, with no increased – or even reduced – risk of
container damage.
The system also opens the use of flexitanks to the wider global
container asset base, CSM says. Currently, containers have to be
carefully selected before fitting with a flexitank to ensure that, for
example, the sidewalls are sufficiently robust to withstand the
dynamic forces of the liquid while in transit. And, if a container is
damaged during transit it cannot be reused for a flexitank shipment
until it has been repaired.
But as the FlexiBin S3 is said to minimise the impact of these forces
on the sidewalls and doors, a much larger population of standard
containers becomes available for shipping.
The system achieves this by physically removing over 6,600kg
of load from the sidewalls as opposed to reinforcing the latter.
CSM has manufactured and tested FlexiBins to prove their massive
strength. The tests verified their finite element analysis and just to be
sure, a standard container was tested to destruction using the same
tests. The FlexiBin came out at a 35 percent strength improvement
with no failure.
The system can also be used as a pressure vessel by mating one
unit on top of the other. This would be an effective solution for
the transport of carbonated products where pressure containment
is a consideration.
An optional reefer design comprises a reefer version which securely
locates to the T-bar flooring and solves an age-old problem of how
to operate a flexitank in a reefer.
A heating option will be soon be available. This involves a
series of steel heating tubes housed in the hollow wall sections
of the FlexiBin S3, through which high-pressure steam can be
accommodated. Coupled with an increased heating contact surface
this will significantly reduce heat up time.
However, there is also the issue of what to do with the FlexiBin
trays after each shipment. McKenna says the return logistics are still
attractive as, even when a return payload cannot be secured, the
trays can be stacked up to eight units in a standard 20ft box, nine in
a 20ft high cube container, or 18 in a 40ft high cube.
Low manufacturing costs and robust design and construction make
the FlexiBin S3 very economical on a per trip basis in addition to the
additional payloads achievable, CSM maintains.
The FlexiBin S3 is positioned and stabilised in the container using
purpose-built corner locks at front and rear. It can accommodate at
least four anti-surge padded straps along its length if required, as
well as two off-bracing bars fitted across the door opening.
A five-sided full height reusable liner can be fitted acting as a
secondary containment system, with the liner attached to top
lashing rings. Other options include a fitted sealed valve cap and
drain plug to allow drainage.
In the 40ft container version both tanks can be filled and
discharged from the rear by means of a hose running from the rear
tank to the door end.
Further details of the FlexiBin S3, as well as technical specifications
can be found on the website:
www.brendanmckennaassociates.com/Case%20studies.html
40ft containers
The FlexiBin S3 weighs just 825 kg
CSM has also developed a design for carrying two FlexiBin S3 units
in a standard 40ft container. Certain trades have large inventories of
40ft boxes which could now be exploited for flexitank shipments.
This could be in the form of two shipments of 13,000kg of the
same product, or, perhaps more interestingly, two shipments of
different products.
CSM is keen to get the product into the field and tested in a live
operating environment. “The physical testing already carried out was
very successful and the product did exactly what it was designed to
do – carry higher payloads safely and without damage to the
container sidewalls,” said McKenna.
Moreover, the onset of the SOLAS requirements for verified gross
mass (VGM) weighing of containers provides added impetus for the
safe carriage of product, an issue for which he believes the FlexiBin
S3 “ticks all the boxes”.
Mating one unit on top of the other would be a solution for transporting carbonated products
where pressure containmen t is a consideration
The system makes no contact with container side walls even under dynamic load conditions
A purpose-built lightweight lifting frame to handle the FlexiBin 3s fits all forklifts
Static force removed from container side wall. Actual force may differ by tank type and design.
Figures represent a typical 24,000 litre load
Tandem configuration for 40ft container.
The units are locked together centrally at
corner fittings
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