Op-Ed: Tank coatings and linings to protect the harshest area of a vesselWritten by
By Andy Margarit, Sales Director of Marine at Tnemec Company Inc.
The start of 2020 is remembered for a myriad of reasons, but for those in the marine industry, the International Maritime Organization’s IMO 2020 rule is likely a front runner. Taking effect on January 1, 2020, the rule lowered allowable amounts of sulfur discharge from exhaust systems from the previous 3.5% m/m to 0.5% m/m. While this has a positive impact on the environment, it’s no secret it caused a bit of a headache for ship owners around the world.
Vulcan Materials Company was one of many companies facing the impact of this change on its 751-foot bulk carrier, the Donald M. James. To meet the new requirements, the company installed scrubber systems on their vessels. These systems take the exhaust fumes and filter the sulfur out through various water tanks. This was the most logical fix, but it certainly didn’t come without challenges. As the sulfur builds up in the tanks, it becomes more and more corrosive to the steel. To protect these tanks, a pin-hole-free, high-performance lining, was required. In this case, a specialty vinyl ester coating system was the best option. For the Donald M. James, that’s where the real challenges began.
Protecting the scrubber tanks
While the Donald M. James was a newer vessel, built in 2018, the original coatings systems on the scrubber tanks experienced early failures. When the ship was docked at the Austal Shipyard in Mobile, Ala., replacing these coatings systems was the first order of business. With the help of Wilhelmsen Ship Management (WSM), the team set out to find the right coatings system for the job. But there was one more problem: Raw materials to develop the necessary vinyl ester coatings system were in short supply and have continued to be for more than two years.
Having already blasted the tanks to remove the previous coatings, and with a short time frame to get the ship up and running, the team needed a solution fast. WSM contacted several suppliers looking for vinyl ester systems that could be specified and applied in time. That’s when they reached out to Tnemec and the local agency in Alabama, SteelCon Coatings Systems.
Finding the right coatings system
WSM worked with SteelCon to quickly provide a project specification for the vessel’s tanks, a complete system with primers, finishes and ancillary products that would withstand the harsh conditions created by the sulfur for longer than the previous system. Understanding the urgency and knowing most vinyl ester coatings are “made to order,” Tnemec was able to speed up the manufacturing timeline to enable WSM to receive the coatings needed in time to complete the job.
The specification included a complete vinyl ester system using Tnemec VINESTER 1407, 1436, and 1416. The team also added fiberglass chop strand mats to areas that typically see coating failures for added protection. This included over welds, stiffeners, and across the entire bottom of the tank to three feet up the bulkheads. Once the coatings were onsite, WSM, Tnemec, and the application team from TAM Services got to work, maneuvering through the small interiors of the tanks to complete the project.
Many coating companies cannot afford to field support their products and the applicator and owner are on their own, hoping for the best results. Not at Tnemec. A Tnemec NACE Certified Coatings Inspector was assigned from Tnemec’s deep bench of field technical service representatives and remained onsite throughout the duration of the application of the first tank to ensure the coatings were applied to specification. The vessel captain, WSM, TAM Services, and Tnemec worked together to apply the extremely technical system, all while navigating the small confines inside the tanks.
The application team from TAM Services started by applying a stripe coat of Tnemec VINESTER 1407 on the tank welds and then a full coat of 1407 was applied to the entire tank. Next, a coat of Tnemec VINESTER 1436, a premium grade novolac vinyl ester with glass flakes in the lining was applied at 25-30 mils and immediately embedded with a corrosion-resistant fiberglass chop strand mat. The reinforcing mat was wetted with VINESTER 1416, a pure novolac vinyl ester, referred to in the business as a saturant coat. A coat of 1436 at 25-30 mils was then applied three feet up the bulkheads and the floor was completed with the coating/mat and saturant system. The tanks were then ready for a finish coat. 1436, in a bright white finish, improving visibility in the enclosed space, was applied over the entire surface as the final protective layer.
The finished product
The project took a total of two weeks to complete. Within that time, more than 400 gallons of paint were used on the tanks. Despite the challenges many coatings companies were facing in supplying vinyl ester systems, Tnemec was able to deliver the coatings directly from the manufacturing plant in Kansas City to the ship docks in Mobile, avoiding delays in freight transit time. This kept the project on track allowing the vessel to leave the port on time. The Donald M. James is now back at work, transporting limestone aggregate between Mexico and the U.S. Gulf Coast.