Soft-shell military fuel bladders vs hard-shell metal fuel tank
Since their adoption in the second half of the twentieth century, soft-shell fuel bladders have become a fixture of defense operations. Their ability to be deployed quickly and their relatively low initial purchase price have made them an obvious choice as a first-response fuel supply. But how do they perform beyond the initial stages of an operation compared to more robust hard-shell fuel tanks?
What is a fuel bladder tank?
Bladder tanks, also called blivets and fuel bags, are collapsible, soft-wall fuel storage solutions made from fuel-resistant, flexible fabrics. They can range in size from small-scale bags to large-scale pillow tanks that can potentially store tens or hundreds of thousands of gallons of fuel.
Their low initial cost and capacity for establishing a fuel supply point during emergency deployments have meant that they’ve been used in many recent operations. But, as conflicts and requirements evolve, are they still the best choice for tactical fuel storage in austere locations?
What is a hard-shell fuel tank?
Hard-shell, or hard-wall, fuel tanks are rigid containers designed to securely store fuel and facilitate refueling even in harsh, expeditionary environments. Their specs and features vary by manufacturer, but throughout this article, when we talk about hard-shell fuel tanks, we are talking specifically about those manufactured by Western Global.
They are made from steel and double-walled, with an inner tank that holds the fuel and an outer shell providing 110% containment to prevent leaks and spills (eliminating the need for secondary containment) and protect the tank against damage.
Their rigid construction also allows for features that aid operational use. Lockable pump bays and fuel gauges support fuel security and inventory management, while built-in mountings and fittings allow them to be moved and transported easily and interface with US & NATO equipment – delivering fuel agility when it counts.
The pros and cons of soft-wall bladder fuel tanks vs hard-wall tanks
Conflicts are changing. Geographical and operational conventions are shifting, and fuel requirements are evolving alongside them. Where a static, vulnerable fuel supply may have sufficed, this is now often inadequate.
As the concept of ‘walking infantry’ is replaced or supported by manned and unmanned vehicles, mission sustainability will depend on the availability of fuel and agile fueling positions.
We look at the key requirements for modern expeditionary fuel storage and assess them against the capabilities of soft-wall bladders and hard-wall fuel tanks.
Transportability
Bladder tanks are frequently used as a first-responder fuel system. When empty, they’re light, maneuverable, and can quickly be delivered and set up to create an initial supply of fuel. But after this, their utility decreases, and in many cases, they are left operating a long time after they should have been replaced or upgraded.
Emptying a bladder tank for transport is extremely labor-intensive and very difficult to achieve. When filled, large bladder tanks can’t easily be moved. Even where this is theoretically possible, it comes with a huge logistical burden. Specialist equipment is needed, and their amorphous shape and potential for fuel to slosh around during transport create instability and increase the potential for tears or punctures – a hazard they’re already vulnerable to.
Western Global’s hard-shell tanks are built as CSC-approved 20ft / 40ft ISO Containers and therefore can be transported by air, sea, rail and road, with certain tanks able to be moved as required when filled with fuel for easy redeployment if your mission changes. Their tough construction means they can be repeatedly moved, with little risk of damage or loss of supply – allowing them to be easily relocated in contested logistics.
Inventory management
Having an accurate picture of your fuel inventory is critical. Uncertainty around your true fuel supply can create assumptions that lead to inefficiencies and wastage, or, in worst-case scenarios, mission failure.
Tracking fuel is notoriously difficult with fuel bladders. Methods have included using a gauging stick at the side of the bag with a string attached to the central vent. This is wildly inaccurate, even before accounting for condensation and temperature-based expansion. Other solutions include a weighing scale beneath the bag – a further logistical burden that isn’t practical in most operational scenarios.
Hard-wall fuel tanks can be fitted with percentage gauges that provide a completely accurate reading at a glance. There’s no extra labor or specialist equipment required to understand your true fuel availability.
Security
Many bladders are sold as ‘specially toughened’, or featuring a new, ultra-resistant composition, but there’s no escaping the fact that they’re constructed from fabric. They’re susceptible to punctures and tears, and have seams that will always be their weak point. Add to this the risks of material degradation from heat and UV light, and it’s a less-than-ideal level of security for such an essential asset.
A hard-shell fuel tank provides real protection against tactical hazards. Above being resistant to tears or punctures, they are resilient against real operational risks – making them a secure fuel storage option in forward environments, or anywhere a fuel supply may be in peril.
Secondary containment
Due to the risk of spillage or leakage, fuel bladders require secondary containment. This means either transporting a containment berm along with the bladder or digging a containment dike. But, this isn’t always a possibility. Some host nations, particularly in Eastern Europe, prohibit groundworks.
Western Global hard-shell tanks have built-in, double walled 110% secondary containment – eliminating the need for drip trays or containment berms. They can be unloaded onto any hardstand without any need for groundworks and be ready to deliver fuel.
Environmental impact
Under previous operational conditions where fuel leaks and spills were largely overlooked, bladder tanks and their inherent failure rate were frequently considered operationally acceptable. As operations and deployment change toward more environmentally sensitive locations, this can no longer be relied upon. In the emerging AOR of INDOPACOM, a fuel leak on a Pacific island could have potentially disastrous environmental consequences and a huge impact on the ecosystem.
Hard-shell fuel tanks with integral double walled containment have a far lower risk of accidental spills or leaks, and are far less likely to be compromised as a result of damage, making them the most practical option for fueling in sensitive environments.
Value
Bladder tanks have a cheaper upfront cost than other tank types and are marketed as reusable. As we’ve discussed, their limited shelf life, the risk of damage, combined with their acceptable failure rate, often means replacements are needed.
There’s also the question of reuse. We’ve looked at the difficulty of emptying them. They are frequently treated as a single-use asset, and the number of fuel bladders that are reused is likely to be low. With this in mind, the value drops dramatically when compared with a truly reusable hard-wall tank.
Fuel bladder or fuel tank?
Supply chains are going to be tested by the rapid insertion, speed and range of modern combat. Hard-wall fuel tanks are the only true ‘plug and play’ fueling solution. They can be shipped globally, transported by rail, road or sea and set up, ready to fuel within a matter of hours
They also offer the best long-term value with an operational lifespan of 20+ years, several times that of a bladder, with the ability to be completely emptied, de-gassed, cleaned and re-used as many times as necessary.
Western Global manufactures a comprehensive range of military spec fuel tanks and dispensing equipment. Contact our defense experts to find out more.
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