Stainless? Zinc? Epoxy? What kind of other coating available for chemical tankers? Which one Koyo Kaiun using for short sea trade?

There are many types of tank coating materials, and it is often very confusing to understand which one has what kind of characteristics and is suitable for which type of cargo. We now use only stainless steel tankers for our short sea, and this is the reason behind our choice.

Stainless steel
Stainless steel tanks are highly durable, resistant to corrosion, and easy to clean and maintain. The primary benefit of stainless steel tanks is their exceptional longevity, making them ideal for storing liquids and substances that could degrade other coated tanks such as zinc, epoxy, or MarineLINE. These tanks are non-porous and non-reactive, so they do not retain or absorb odors, flavors, or chemical substances from their previous cargo. This significantly reduces the risk of cargo contamination from previous loads. Furthermore, stainless steel tanks require less time for cleaning and are capable of withstanding high pressures during the cleaning process.

Koyo Kaiun is using six small to medium-sized chemical tankers, each with a capacity between 8,500 and 14,000 deadweight stainless steel ships. They frequently visit Singapore, Malaysia, Thailand, and Indonesia, stopping at each destination more than 10 times per month. Due to the short duration of the voyages—2.5 days to Thailand and 2 days to Indonesia from Singapore—frequent tank cleanings are necessary to prepare for the next cargo load. This high turnover rate is why stainless steel is the preferred material for our short sea trade lane.

Zinc coating
Zinc coatings provide strong mechanical protection, yet they have limited operational capabilities and are susceptible to damage from acids, caustics, oils containing acids, and urea. While some shipowners opt for zinc-lined vessels for transporting methanol, this choice restricts the flexibility of their fleet, leading to financial losses if the ship returns empty after methanol delivery. Furthermore, zinc's high absorbency may cause cargo residues, compromising the purity of subsequent loads and reducing the options for carrying different products. Since short sea trade is characterized by high turnover and we have to load sensitive cargo, stainless steel is the preferred material for our operations.

Epoxy coating
Around 59 percent of the chemical tanker market uses conventional and phenolic epoxy coatings. These coatings are suitable for transporting a range of substances, such as certain organic acids, alcohols, edible oils, fats, and solvents. However, they are not ideal for highly corrosive liquids. Manufacturers often recommend avoiding aggressive cargoes for the first three months. After transporting a harsh chemical, a milder, approved cargo is necessary to avoid damaging the coating. This need to carefully manage cargo types affects cargo sequencing profitability and reduces operational flexibility, diminishing earnings. We frequently load a variety of chemicals and acids, and the stowage requirements change daily as new cargoes arrive. Consequently, it's impractical to determine which tanks are unsuitable for specific substances. For this reason, we opt for stainless steel tanks.