Composite tanks store chemicals in Middle East project

RL Industries used filament winding and epoxy vinyl ester from AOC to make massive composite tanks for storage of a solution of 32 percent hydrogen chloride or 20 percent sodium hydroxide.

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RL Industries (Fairfield, Ohio, USA) reports that it overcame logistical obstacles to successfully fabricate composite storage tanks for a chemical plant in Saudi Arabia. To resist the highly acidic nature of the storage media, the resin chosen for the tanks was Vipel F010 bisphenol A, epoxy vinyl ester from AOC (Collierville, Tenn., USA).

The job required three large composite tanks to store a 32 percent solution of hydrogen chloride or a 20 percent solution of sodium hydroxide. Compared to on-site fabrication, RL Industries’ dedicated manufacturing facilities eliminated the potential for ambient contamination and provided better control of process parameters. In addition, the company’s manufacturing is certified to demanding American Society of Mechanical Engineers standards for corrosion-resistant structures.

RL Industries’ strategy started by filament winding cylindrical sections of Vipel resin-impregnated fiberglass roving. Winding was accomplished over a high-performance corrosion barrier, formed with chopped strand mat and two layers of carbon veil in the Vipel resin matrix. Nozzles and attachment features for ladders and rails were integrated into the wound sections.

To mold top and bottom end closures, the Vipel resin was vacuum-infused through fiberglass reinforcements and structural sandwich core. For enhanced load-bearing, RL Industries designed the bottom end closure with an integral, high-strength knuckle radius. The top and bottom end closures were integrated into the cylindrical shell during the shop winding process.

After the tank sections were manufactured, they were assembled at a site 20 miles/32 km) away. Special permits were obtained to ship the tank sections over the road to the assembly site. At the assembly site, the cylindrical sections were sequentially assembled using laminating techniques that are similar to the way chimney liner “can” sections are joined. The end-result for each tank was a high-strength, monolithic structure ready to go to work when installed.

RL Industries made three 20-ft/6.1m-diameter chemical storage tanks for the project. One tank was 47.7 ft/14.5m high; the other two were 41.3 ft/12.6m high. The tanks were design-engineered for 8 inches (+20 mbarg) positive pressure and 1.2 inches of water (10 mbarg) negative pressure. The design temperature is 194°F/90° C.

The contract also called for two 7-ft diameter by 16-ft high (2.1m by 4.9m), shop-fabricated tanks for holding non-potable water for emergency safety showers. To keep ambient Saudi temperatures from making the water too hot, these tanks have 2 inches/50 mm) of sprayed urethane foam insulation encapsulated within the laminate.

After all tanks successfully passed hydro-testing protocols, they were loaded on a barge for transport down the Ohio and Mississippi Rivers to a Gulf of Mexico port. The equipment was then transferred to an ocean-going vessel for shipment to Saudi Arabia.