Storage tanks installations

The earthquake response, as a direct time-domain representation, of the cylindrical liquid storage tank installed in the water-saturated transversely isotropic soil strata can be obtained by employing the numerical models of the cyHndrical tank structure, the stored liquid, the near-field region of the ground, and the transmitting boundary. The equations of motion for the tank structure, the stored Hquid, and the near-field region of the ground can be written in the time domain as follows ... 

Part 2, paragraphs 44-46 Management of instrumented systems for fuel storage tank installations, paragraphs 47-68... 

Management of instrumented systems for fuel storage tank installations... 

It is mainly supplied liquefied under pressure in compressed gas cylinders. At high demands, nitrous oxide is also supplied by special tank trucks and filled into storage tanks installed on-site from where the centralized supply in the hospital is possible. 

Glean Water Act. The Water QuaUty Act of 1987 and Clean Water Act of 1977 amended the Water Pollution Control Act of 1972, and are known collectively as the Clean Water Act (CWA). Their objective is to restore and maintain the integrity of U.S. waters. There are spill prevention, control, and containment requirements with which to comply. It requires replacement of older storage tanks or installation of double bottoms or seals. 

Anodic passivation and its appHcation to sulfuric acid equipment such as stainless steel acid coolers and carbon steel storage tanks has been weU studied (102—104). More recently, sheU and tube coolers made from Sandvik SX or Saramet have been installed in several acid plants. These materials do not requHe anodic protection. 

Vaulted. Vaulted tanks are installed inside a concrete vault. The vault, itself a Hquid-tight compartment, reduces the fire protection requirements as the NFPA and the International Fire Code Institute (IFCI) recognize these tanks as fire-resistant aboveground storage tanks. The vault provides a two-hour fire wall, thermal protection that minimizes tank breathing losses and pollution, secondary containment, and baUistic protection. 

Contrac tors bids offer the most rehable information on cost. Order-of-magnitude costs, however, may be required for preliminary studies. One way of estimating them is to obtain cost information from similar facihties and scale it to the proposed installation. Costs of steel storage tanks and vessels have been found to vaiy approximately as the 0.6 to 0.7 power of their weight [see Happel, Chemical Process Economics, Wiley, 1958, p. 267 also Williams, Chem. Eng., 54(12), 124 (1947)]. AU estimates cased on the costs of existing eqiiipment must be corrected for changes in the price index from the date when the equipment was built. Considerable uncertainty is involved in adjusting data more than a few years old. 

Based on a sui vey in 1994 for storage tanks, the prices for field-erected tanks are for multiple-tank installations erected by the con-trac tor on foundations provided by the owner. Some cost information on tanks is given in various references cited in Sec. 25. Cost datavaiy considerably from one reference to another. 

In addition, restrictions on industrial air emissions under the Clean Air Act (CAA) as amended in 1977, the Clean Air Act Amendments (CAAA) of 1990, and other state and local statutes and regulations have universal impact on the storage of toxic materials, with direct and significant effects on the design and operation of toxic material storage facilities. Whereas the primary factors which once determined how air emissions from storage tanks were handled were fire protection and loss prevention, in recent years environmental protection concerns nearly always determine the extent and nature of the air emission controls required to be installed. 

In the cathodic protection of storage tanks, potentials should be measured in at least three places, i.e., at each end and at the top of the cover [16]. Widely different polarized areas arise due to the small distance which is normally the case between the impressed current anodes and the tank. Since such tanks are often buried under asphalt, it is recommended that permanent reference electrodes or fixed measuring points (plastic tubes under valve boxes) be installed. These should be located in areas not easily accessible to the cathodic protection current, for example between two tanks or between the tank wall and foundations. Since storage tanks usually have several anodes located near the tank, equalizing currents can flow between the differently loaded anodes on switching off the protection system and thus falsify the potential measurement. In such cases the anodes should be separated. 

For economical and complete cathodic protection against external corrosion without harmful effects on nearby installations, the storage tank to be protected must have good coating and therefore require a low protection current density. In addition, it must have no electrical contacts with other buried installations, such as... 

For installations with several storage tanks and a protection current of several tens of an mA, uniform protection current distribution should be the goal, so that the current injection occurs via a number of anodes distributed over the site or via a more distant anode bed. Dividing up the protection current over several anodes avoids large local anodic voltage cones and therefore effects on neighboring installations. 

Protection currents of a few amperes are needed for the cathodic protection of assemblies of storage tanks or refuelling stations. In this case, electrical contact with grounded installations is the main problem. For cathodic protection, these contacts must be located and electrically separated. If this is not possible, then local cathodic protection should be installed (see Chapter 12). 

At the relatively low protection current density of 200 llA m and with the anode positioned on one side, it is to be expected that with this storage tank sufficient reduction in potential would be achieved on the other side of the tank from the anode. The off potential was measured using a measurement point at a depth of about 2 m as f/cu-cuso4 = -0.88 V at the tank. At the other side of the tank as well as above it, off potentials of-0.90 to -0.94 V were found. These potentials were measured with a protection current of 10 mA (anode 1 6 mA, anode 2 4 mA) with an additional resistance of 8 Q in the protection current circuit (see Fig. 11-2). With a direct connection between the tank and the group of magnesium anodes, the initial current was about 16 mA, which after 1 h of polarization decreased to about 14 mA. The reserve current, based on a long-term current of 10 mA, amounted to ca. 40% in the operation of the cathodic protection installation. 

Tank installations with underground storage tanks and station piping should, if possible, be provided with conventional cathodic protection [3]. This is sometimes not possible because electrical separation cannot be achieved between the protected installation and other parts of the plant (see Section 11.4). The necessity for cathodic protection can be tested as in Ref. 13. In tank farms, a distinction should be made between coated, buried storage tanks and aboveground, flat-bottomed tanks in which the base contacts the soil. 

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