Shipping Molasses With Heater Pads for Flexitanks: Viscosity and Winter Discharge
Molasses is one of the most rewarding cargoes to ship in bulk and one of the most difficult to unload. It leaves the mill as a pourable syrup, which can of course turn to something very much like tar on a cold voyage. That’s where heater pads for flexitanks come in. In our experience, the exporters who plan to heat prior to even leaving the port get the cleanest discharge at destination.
What is molasses and why is it shipped in bulk?
Molasses is the thick, dark syrup that is the residue after sugar has been extracted from sugar cane or sugar beet. The main uses for it are as animal feed and in the production of ethanol (fermentation), with smaller volumes used in food.
Because demand runs into thousands of tonnes, shipping it in drums makes little sense. A single flexitank turns a standard 20-foot container into a sealed tank holding up to 24,000 litres. Our flexitanks for bulk liquid transportation use multi-layer polyethene, which keeps the cargo clean and protected for the whole journey. For many sugar exporters, this has become the simplest route into bulk liquid transport.
What makes molasses difficult to ship?
The main challenge in bulk molasses transport is viscosity. Viscosity is a measure of how thick a liquid is and how much it resists flowing. Water has very low viscosity, while molasses has an extremely high one.
This creates a chain of practical problems. Thick molasses discharges slowly, and some of it clings to the bag. Our team often sees receivers lose hours at the unloading point because the cargo will not move. Those hours can quickly turn into demurrage charges.
Why does molasses get thick in winter?
Molasses gets thicker as it gets colder, and its viscosity in cold weather can stop it from flowing almost completely. Warm molasses pours with some ease, but cold molasses can barely flow at all.
Did you know? Research from James Cook University in Australia has shown that the viscosity of the final molasses is most sensitive to temperature in the range 20-50c. Within that range, a small rise in temperature makes the syrup a lot easier to pump.
In winter, the containers can be in cold ports or can be transiting through a cold area. By the time they get there, the cargo right up against the walls and floor has often gone stiff. A large proportion of the load may well be in the bag without any heat at all.
How do heater pads for flexitanks help discharge?
A flexitank heating pad is a flat heating layer placed under the flexitank before loading. At destination, the receiver connects it to a steam or hot water supply. The pad then warms the cargo from below, so the molasses softens and flows toward the valve.
Gentle, even heating is the key here. Molasses will lose its quality if any small area gets too hot, so a pad that spreads the heat out over the whole base is by far the safer option than direct, focused heat. More info on how the flexitank heater pads work can be found here.
| Factor | Without heating pad | With heating pad |
| Flow rate | Very slow | Steady |
| Discharge time | Long and unpredictable | Shorter and easier to plan |
| Residue left in bag | Often high | Much lower |
| Winter performance | Cargo may stay solid | Cargo softens before unloading |
Tips for a smooth winter discharge
Plan the heating prior to the container’s arrival. The receivers should have steam or hot water arranged at the unloading site in advance so that heating can commence as soon as the container gets there.
Allow extra time in cold months, because thick cargo needs longer to warm through. It also helps to keep the discharge hose and pump warm, since molasses can thicken again inside a cold line. For cold route shipments in general, our article on winter shipping solutions covers the wider picture.
Once these steps become routine, molasses turns into a far more predictable liquid cargo transport job. Heater pads for flexitanks remove most of the guesswork from cold weather unloading.
Ship molasses with confidence
Molasses rewards good planning. With the right flexitank and a heating pad fitted from the start, exporters can protect cargo quality and cut costly waiting time at the receiving end.
Fluid Flexitanks supplies flexitanks and heating pads built for thick, temperature-sensitive cargo. Speak to our team about your next molasses shipment, and we will help you choose a setup that suits your route and season.
FAQ
Molasses has very high viscosity, so it flows slowly and clings to the flexitank. Cold weather makes it even thicker, which leads to long discharge times, residue left in the bag and possible demurrage charges.
Molasses gets thicker as its temperature drops. Containers that travel through cold regions or wait in winter ports often arrive with stiff cargo near the floor and walls, which will not flow without heating.
A flexitank heating pad sits under the flexitank. At destination, it connects to steam or hot water and warms the cargo from below, softening the molasses so it flows toward the valve for discharge.
Gently and evenly heat the molasses using a heating pad underneath the flexitank. Arrange your steam or hot water prior to the container arriving, allow extra time in the winter and keep the discharge hose warm to prevent the molasses from thickening.
Gently and evenly heat the molasses using a heating pad underneath the flexitank. Have steam or hot water ready prior to the container arriving, allow extra time in winter and keep the discharge hose warm to prevent the molasses from thickening.
