Marine Terminal Selects Advanced Tank Coatings

A state-of-the-art tank storage farm will utilize advanced tank coating technology to keep its expansion project on the fast-track. In the process, efficiency will improve and capital investments will be protected long term.
By Alan Burton | November 11, 2009
In 2007, a two-year, multi-million dollar marine terminal expansion project at the Port of Wilmington, Del., was launched in an effort to provide more than 1 million barrels of additional storage space for gasoline and ethanol products used by one of the terminal's long-time lease customers.

The marine terminal already had the capability of storing and distributing heating oil, ultra-low sulfur diesel, heavy fuel oil and marine diesel oil. However, to accommodate the lease customer's storage needs for gasoline and ethanol fuels, three of the existing tanks at the facility would have to be converted from heating oil to gasoline and ethanol service. This required that specially formulated tank linings be installed to handle the new fuels, while also meeting local Department of Environmental Protection and U.S. EPA requirements. The expansion project would also include the construction of 11 new tanks with related terminal infrastructure, the upgrade of an existing truck rack to handle the new fuel products, and the installation of a marine vapor combustor to an existing dock that will allow the terminal to transfer gasoline and blendstock to and from barges and ships. Marine terminal workers will combine the gasoline and ethanol fuels as they load the lease customer's trucks, creating an E10 fuel blend.

During the project's bid process, representatives from International Paint Protective Coatings were invited to make a presentation to the project's owners and engineering staff to introduce two innovative coating technologies, which were developed for the construction and maintenance of tanks in oil and gas environmentsŻand specially designed to help speed construction schedules, minimize environmental impact and extend maintenance life cycles.

The first coating technology presented was Interplate 937, a heat-resistant, zinc-rich, preconstruction primer that allows the coating to be spray-applied to blasted steel in a controlled fabrication shop environment prior to field construction. This highly durable primer can withstand temperatures of up to 1,472 degrees Fahrenheit and provides excellent abrasion-resistance during speed-welding and cutting, with minimal output of zinc salts. Water soluble zinc salts can be especially troublesome, because as the moisture vapor ions penetrate the coating, they are drawn to the soluble salts and form into a water molecule. As this process repeats itself, a water blister develops and the top coats become blistered or completely detached from the steel beneath.

The terminal's owners were especially interested in this coating option not only because of its advanced corrosion protection properties, but also because it would significantly reduce the time and labor costs associated with full open blasting and priming of the tanks onsite, while helping to prevent unnecessary damage from overspray to the new cars being unloaded from ships at the Port of Wilmington and stored near the marine terminal's fence line.

The second technology presented was a mildew-resistant version of Interthane 990UHS, a low volatile organic compound (VOC), acrylic polyurethane topcoat specially formulated for steel tanks that store ethanol, as well as pipes and other exposed steel structures in highly corrosive oil and gas environments. The process of producing ethanol from corn includes the use of micro-organisms or "bugs," in the form of yeasts and molds. These bugs eventually turn into the unsightly black mildew that commonly appears on ethanol tanks. Using the patented mildew-resistant technology will not only help maintain a clean white appearance on the tanks, but its excellent gloss retention capabilities will help terminal owners extend the cleaning and maintenance cycle of the tanks and piping long-term.

These unique, time- and cost-saving technologies finally convinced the owners and project engineers to specify the coatings for the marine terminal expansion project. Application of the preconstruction primer began at the plate fabricator's facility in February 2008, using the Redi-Plate system., a fabrication process ensures each plate is prepared and coated to the highest industry standards, meeting ISO 9001 "best practice" manufacturing plant procedures.

After all contaminants such as chlorides, oil, grease and other foreign matter were removed from the large steel plates; they were abrasive cleaned according to the joint Near-White Blast Cleaning specification of The Society of Protective Coatings and National Association of Corrosion Engineers (SSPC SP 10 / NACE No. 2), in order to produce a sharp, dense surface profile of 1.5 mils to 2.5 mils. The surface profile was carefully measured using the ASTM D 4417 test method and then preheated to 110 F to detect any major steel defects.

The preconstruction primer was applied by computer-controlled spray application equipment to ensure a closed, dry film thickness of 0.6 mils to 0.8 mils. Dry film thickness was continuously monitored and verified using polyester plastic control panels, which are temporarily attached to the plate during processing. The completed plate was visually inspected for any surface anomalies and then marked with a batch number to ensure traceability.

This unique fabrication process, in tandem with the performance capability of the preconstruction primer, can provide up to six months of protection against corrosion due to weather exposure, as well as any physical damage to the coated steel plates during transportation to the construction site.

After the steel plates were primed and formed to design specification, they were shipped to the marine terminal for erection by the general contractor. Paint crews then roll-applied Interseal 670 HS, a low VOC, high build, high solids surface tolerant epoxy coating to provide additional corrosion protection for the new tanks. Unlike most epoxy coatings that cannot cure in temperatures lower than 50 F, this versatile intermediate maintenance coating has excellent wetting properties and is formulated for rapid cure in temperatures as low as 23 F, thereby allowing construction schedules to stay on track during seasonal weather changes. Another advantage of Interseal 670 is that it does not require that an accelerator be added to the coating to achieve the low-temperature cure capability, thus eliminating the risk of yellowing and embrittleing commonly experienced with accelerator additives. The final step in the exterior tank coating system was the roll-application of the mildew-resistant polyurethane.

The interiors of the 11 new tanks and three converted ethanol tanks were spray-applied with Interline 984, a solvent-free corrosion-resistant, epoxy phenolic-based lining. This heavy-duty, 100 percent solids lining is capable of being used as either a single-coat unreinforced system, or in conjunction with fiberglass to form a glass-reinforced laminate system. The lining is specially formulated with fast-acting chemical-resistant properties, which help extend the maintenance schedule for re-coating. In addition, the coated interiors can be rapidly returned to service in as little as 24 hours, thereby significantly reducing production downtime.

More than 9,000 gallons of paint will be used to coat the interior and exteriors of the new and existing tanks, terminal piping, vapor combustion unit and fire suppression foam system. Another 1,000 gallons will be used to coat 150,000 square-feet of piping for the new marine dock facility and truck loading rack.

By using the innovative tank coatings system for the expansion project, marine terminal owners were able to net significant savings in labor costs through automated surface preparation and shop application of the primer prior to construction. Not only did this put them ahead of their construction schedule, but it will add years of additional savings in maintenance costs by including the low-temperature, rapid-cure epoxy intermediate coating and mildew-resistant polyurethane topcoat to the mix. The expansion project is slated for completion in late 2009, making it the most modern gasoline distribution facility in the Philadelphia area.

As the oil and gas industry continues to expand its production, storage and distribution capabilities, owners will increasingly look to their supplier relationships for new technology solutions that help them protect their capital investments, control construction costs, and extend the maintenance life-cycle of existing assets. EP

Alan Burton is the RUSA Oil & Gas Market Manager at International Paint Protective Coatings. Reach him at www.alan.burton@akzonobel.com.