Cargo tank

Tanl . Coatings for Hquid cargo tanks ate selected according to the materials that the tanks (qv) ate to contain. Tank coatings protect the cargo from contamination and must be compatible with the material carried. Epoxy systems ate most frequendy selected because they perform well with both aqueous and organic products. A carefully appHed three-coat epoxy system having a dry-film thickness of 225—300 pm can be expected to last for 12 years. 

Truck cargo tanks (for dangerous materials) are built under Part 173 and Siibpart J of Part 178, DOT regulations. This includes Specifications MC-306, MC-307, MC-312, and MC-331. MC-331 is required for compressed gas. Siibpart J requires tanks for pressures aoove 345 kPa (50 Ibf/in ) in one case and 103 kPa (15 Ibf/in ) in another to be built according to the ASME Pressure Vessel Code. A particular issue of the code is specified. 

As of November 1.1981. identification numbers are required on portable tanks, cargo tanks, and tank cars. 

The International Maritime Organization (IMO) published a standard in 1984 for the design, testing and locating of deflagration and detonation flame arresters and high velocity vent valves for cargo tanks in tanker ships (IMO 1984). This was amended in 1988 and reissued as Revision I (IMO 1988). A new revised standard was issued in 1994 (IMO 1994). 

Schampel, K. and Steen, H. 1975. Flame Arresting High Velocity Valves on Cargo Tanks of Tankers for Inflammable Liquids./. Hazardous Materials, 1, 223-235. 

The IMO standard MSC/Circ. 677 (1994) provides testing procedures for end-of-line deflagration and in-line detonation flame arresters, as well as high velocity vent valves for use on cargo tanks in tanker ships. Its development is discussed in Section 2.3.4. 

The berth area adjacent to tanker and barge cargo tanks is to be Division 2 to the foiiowing extent ... 

The cargo tanks of oil tankers present a special case, because of the high cost of steel renewals in unprotected tanks. For a 30 0001 tanker, costs in the region of 500000 for the initial painting of the tanks have been quoted if the life of the paint system is 6-8 years, the total cost over the normal 20-year life of a tanker is expected to be appreciably less than the sum otherwise spent on steel renewals, which may amount to several hundred thousand pounds. 

The zinc silicate, epoxy and coal tar/epoxy coatings are still used. Coal tar epoxies are used for crude oil tanks, sometimes on all the interior surfaces but more often for a) the bottom of the tank and about 2 m up the sides, b) the top of the tank and about 2 m down the sides, and (c) other horizontal surfaces where seawater ballast may lie. These partly coated tanks are frequently also fitted with cathodic protection to prevent corrosion of the uncoated areas when seawater ballast is carried. The pure epoxy or coal tar epoxy coatings applied in bulk cargo tanks used for the carriage of grain must be approved by the North of England Industrial Health Service, or by similar independent authorities in other countries. 

Klaver, R.F., Electrical Field Strength in Cargo Tanks of Seven Tankers during or after Washing, Chevron Research Co., Richmond CA, November 2, 1971. 

Chubb, J.N., Practical and computer assessments of ignition hazards during tank washing and during wave action in part-ballasted OBO cargo tanks, J. Electrostatics, 1, No. 1, Febru-ary 1975. 

Nitrous oxide is contained and transported in its liquid phase in high-pressure gas cylinders or in liquid cylinders. It is transported as a liquefied compressed gas under high pressure in cylinders and at lower pressures and reduced temperatures in refrigerated cargo tanks and insulated portable tanks. Nitrous oxide is stored in a foam-insulated tank accompanied by a refrigeration unit, which is similar to the tank used for carbon dioxide. 

At 1240 on February 1, 1972, the tankship V. A. FOGG departed Freeport, Texas, en route to the Gulf of Mexico to clean cargo tanks that carried benzene residue. The vessel was due to arrive in Galveston, Texas, at 0200, on February 2. At approximately 1545, February 1, the V. A. FOGG suffered multiple explosions and sank. All 39 persons aboard died as a result of this casualty. Three bodies were recovered two of the bodies were identified and one remained unidentified. The other persons were missing and presumed dead. 

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