MarineLine® E-Newsletters

Profitable Tanker News about Marine Cargo Tank Coatings
Issue 12
MarineLine® Coating Challenges Stainless Steel for Cargo Tanks

MarineLine Coated TankBefore the MarineLine® cargo tank coating system from Advanced Polymer Coatings, stainless steel was typically used for the cargo tanks of chemical tankers. Shipowners invested vast sums for stainless steel construction to provide product purity and to resist corrosion from the chemicals carried.

However, even today, stainless steel is still an expensive metal to use. Special skills are needed for fabricating and welding the stainless steel tanks in the newer, larger volume chemical carriers, thus further increasing construction costs.

Innovation Changes the Industry

It is easy to see how MarineLine® has emerged to capture the imagination of shipowners by carrying the full range of chemicals handled by stainless steel, AND an even more extended product range for greater versatility including aggressive acids. MarineLine® also dramatically reduces overall new construction costs by allowing tank construction with less expensive mild (carbon) steel to deliver faster Return on Investment (ROI). Now, with more than 650 ships operating worldwide and a growing share of the chemical and product tanker market, MarineLine® is challenging stainless steel across all fronts.

Lower Initial Construction SavingsWithout exception, mild (carbon) steel is now the foremost choice for tank cargo tank construction due to its relatively low cost, high mechanical strength and ease of fabrication. A study comparing newbuilding costs illustrates that a ship built with mild steel tanks and coated with MarineLine® costs less than HALF of one with stainless steel tanks. If other costs are factored in such as duplex stainless steel fabrication, the cost comparison makes MarineLine® look even better. Polymer Engineering Translates into Easier, Faster CleaningEasy tank cleaning between cargoes is of vital importance. MarineLine® creates a protective barrier that is easily cleaned, eliminating long ventilation times and putting the ship back into service faster. MarineLine® has a much smoother surface than stainless steel and this superior ‘slip’ promotes significant savings in fuel, energy, time and in cleaning chemicals used, all of which have a positive impact on the environment. With stainless steel, inherent problems with chloride attack can make tank cleaning costly. Typical washing of stainless steel tanks is first carried out with seawater at a certain temperature to remove cargo residues, where possible followed by washing with freshwater to remove chlorides that can damage the stainless steel service. And for some cargoes only fresh water can be used on stainless steel tanks, which are limitations that do not apply to MarineLine®. Less Maintenance, Less Expense Periodic surveys of the tank and regular maintenance are needed to ensure a long service life. In the case of stainless steel tanks, whenever salt water is used for cleaning, fresh water must be used immediately afterwards to remove all salts that can roughen and cause pitting if allowed to remain on the surface. If exposed to halogen salts, especially chlorides that penetrate the surface and allow corrosive attack, stainless steel tanks may need extensive repair and maintenance. Stainless steel tank problems

Maintaining a quality stainless steel tank also requires passivation at various points throughout the cargo tank’s lifecycle. MarineLine®-coated tanks do not require any passivation to deliver a long service, low maintenance life. Key maintenance points for MarineLine® are to only carry approved chemicals, properly clean the tanks, and touch up any areas as needed with the MarineMend coating repair kit.

 Versatility & More Cargo Sequencing PossibilitiesTanker shipowners know their cargo tanks provide their income. MarineLine® allows you to handle the widest range of cargoes possible to ensure full capacity on each voyage and the most profitable high specification cargoes. When customers ask you… “Can you carry….” then the answer should be “yes.” MarineLine® can carry a wide range of aggressive chemicals, CPPs, DPPs, PFADs, bio-fuels, methanol, ethanol and others, and to easily switch between these cargoes, surpassing the capabilities of stainless steel. This higher versatility translates to faster ROI when compared to stainless steel tanks.

Interested in talking more about MarineLine® vs stainless steel? We would like to present the cost savings and ROI possibilities with you for your tanker fleet. Contact your APC/MarineLine representative today.