Sampling fuel oil — the untold story

Every single day, hundreds of ships all around the world have their cargoes sampled — this is an essential part of doing business.

Yep, I have to sample cargoes as well!

The reasons for sampling are diverse — the buyer is interested in testing the quality of the cargo, you have to sample it so you can calculate the mass of product actually being bought, you fear there might have been some cargo contamination among many others. In any case, the reason for sampling a cargo filters up to a final common denominator — money.

If your cargo is not up to specification, it means you lose money. If you are the buyer, it might mean you need to buy other products to put it up to specification, or even that you can’t use that cargo anymore. If you are the seller, if the quality at load port doesn’t match the quality at discharge, you are throwing away money that you could have charged extra.

For instance, let’s say you are selling regular gas. If you load regular gas, but at discharge you find out that you actually loaded premium gas, you as the seller lose money! You could have charged more for it, but didn’t! Now, imagine the opposite — you bought premium gas, but at discharge you find out that what the product on board was actually diesel! Now what can you do, but refuse the cargo?

Those are quite extreme examples that don’t really happen in real life. What is more common is that, due to some issue at load port or on-board the ship, particularly when loading two or more grades of products, you end up contaminating one of them. This, unfortunately, is quite a common occurrence. Normally this is not critical, and you can solve it by either diluting your cargo with a better product or by treating it somehow. But there are cases where the whole cargo is just lost, causing hundreds of thousands or even millions of dollars of losses to all parties.

But what does all this have to do with fuel oil, my fellow reader might ask? Well, everything!

Unlike clear products such as gasoline, diesel and jet fuel, fuel oil is a dark, viscous product that is really, really challenging to work with. Moreover, all modern tankers work with closed systems and inert gas atmosphere, which makes sampling fuel oil really difficult. In many cases, particularly considering Brazilian logistics and production details, your fuel oil don’t have just a single source — it comes from different refineries, in different qualities that are not set at production time. You load whatever the refinery produces, and only after the product is on-board you actually sample it and analyze it!

This is the untold story of fuel oil sampling — unlike refined, clear products, where you can easily know the quality of the product being loaded, fuel oil is a bit of a mystery. You don’t know what you actually loaded until you sample it!

And I have to say this — sampling fuel oil is the most difficult kind of sampling you can have in the maritime shipping industry. For starters, your cargo is normally not homogenized. That means sampling several zones if you want to have a representative sample. Or using a “running sampler” to get a bit of the product from each zone into a single bottle.

Closed sampling system and different sampling bottles

Unfortunately, running samples are a pain. If you do it properly, you could, in theory, get a good sample. But no one does it properly. Picture this — you need to put a bottle with a small hole on the top into a rope, get this bottle all the 30 feet of the ship’s tank, then back up, in a continuous motion, without changing your velocity and then recover the bottle 85% filled. Easy, peasy, right? And that with a product that is about 140°F and is as viscous as honey.

Obviously, this kind of sampling is doomed to failure. So we compromise — we sample the upper, middle and lower level of the ship’s tanks, produce a ship’s tanks composite sample and analyze that.

Unfortunately, that is a gamble. In many cases, this sample ends up with bad results. As I said, our cargo comes from different locations, and the end product will only be analyzed from the on-board sample. If you have a good sample, then that’s great. Often, that sample is not so good.

This results in quality differences from the load port to our destination. Even though we sample the product at the destination in the same way and with the same restrictions as we have at the load port, the cargo at the destination is always in better conditions to be sampled — during the 14+ days that it travelled, it managed to be more or less homogenized, so any sample you take will be a lot more representative of what was actually loaded.

Mostly, this means that we lose some money — we could have sold the cargo at a better price, since we always take a cautious approach so we don’t end up with an off-spec cargo at destination. But once in a blue moon it might mean that we deliver something that the buyer will not be happy with. When that happens, all hell break loose.

Whoever invents a better on-board loading system is going to get a lot of money! While that doesn’t happen, we try to mitigate the issues of sampling by being thorough, knowing what is being loaded to the best of our ability and also by taking in-line samples so we can compare those to the analysis we have of the level samples we took on-board.

Sampling is really important, and more people at the shipping industry should be aware of that!