Preferred Engineering is a full-service engineering and design firm that serves clients in the chemical and refining industries. Its services include unit modifications, expansions, estimating, scheduling, detailed engineering, construction management and staff augmentation. Preferred Engineering s capabilities include computer-aided engineering and automated estimation. Its clients include Air Liquide, Basell, Pasadena Refining Systems, Dianal America, DuPont, Haldor Topsoe, Sea Lion Technology, Shell Oil, Total Petrochemical and Valero Texas City. Preferred Engineering is located in Houston.