STP880: Shell and Jacket Corrosion of a Foamed In-Place Thermally Insulated Liquefied Petroleum Gas Tank

    Taylor, DO
    Engineering consultant group leader of Process Department and supervisor of Technical Support Unit, Arabian American Oil Co., Dhahran,

    Bennett, RD
    Engineering consultant group leader of Process Department and supervisor of Technical Support Unit, Arabian American Oil Co., Dhahran,

    Pages: 7    Published: Jan 1985


    Abstract

    An 87.78 m (288 ft) diameter by 24.77 m (81.25 ft) high liquid butane storage tank was insulated in 1976 using vertically foamed in-place (FIP) low flame spread polyurethane with an aluminum outer jacket. The tank had not been painted since the vendor stated the urethane would not properly bond to painted surfaces. In 1979 corrosion of the aluminum jacket and aluminum rivets was noted. Chemicals, leached from the urethane foam, resulted in streaks of discoloration down the sides of the tank. Detailed inspection in 1980 involved cutting out sections of jacket and insulation to uncover the tank shell. Extensive pitting was noted on the steel shell as well as the foam side of the aluminum jacket. Corrosion is attributed to the intrusion of water from a seawater deluge system that leached the acidic fire retardant chemicals from the urethane foam. A task force was organized to investigate and evaluate various methods for insulating large cyrogenic liquid storage tanks. The study involved visitations both in the United States and Europe. As a result, detailed specifications were developed for the blasting, painting, installation of foam glass insulation, and weather proofing of the tank. Since corrosion had apparently reduced the tank wall thickness below that required by American Petroleum Institute (API) Recommended Rules for Design and Construction of Large, Welded Low Pressure Storage Tanks (API 620), detailed analyses of mechanical properties of the steel were investigated, a program was established to acoustically monitor the tank during hydrotest, and procedures were established for minor localized weld repair to the deepest pits. Details of the inspection procedure, testing, painting, and insulation specifications are discussed.

    Keywords:

    insulation, tanks (containers), corrosion, polyurethane, butane storage


    Paper ID: STP39161S

    Committee/Subcommittee: C16.30

    DOI: 10.1520/STP39161S


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