Condenser Water Boxes

Metal anodes using platinum and precious metal oxide coatings are also incorporated into a variety of designs of impressed current protection for pipeline and deep weU appHcations, as weU as for protection of condenser water boxes in power generating stations (see Pipelines Power generation). 

Examples of the sacrificial-anode method include the use of zinc, magnesium, or aluminum as anodes in electrical contact with the metal to be protected. These may be anodes buried in the ground for protection of underground pipe lines or attachments to the surfaces of equipment such as condenser water boxes or on ship hulls. The current required is generated in this method by corrosion of the sacrificial-anode material. In the case of the impressed emf, the direct current is provided by external sources and is passed through the system by use of essentially nonsacrificial anodes such as carbon, noncor-rodible alloys, or platinum buried in the ground or suspended in the electrolyte in the case of aqueous systems. 

Coat condenser water boxes with protective materials. Special attention should be paid to the tube sheet area and any sharp projections such as nuts and bolts. 

If sacrificial anodes are used in condenser water boxes, it is desirable to select a type that will last for several years. Pure zinc or specially formulated zinc anodes have regained favor in recent years with some operators. High-purity zinc is said to be self-regulating and does not require a resistance to control the current. In some cases, the tube sheet and tube ends also are coated to reduce the current drain on the anodes. 

Common uses of the impressed current method of protection include long transmission pipelines, complex underground structures, marine structures, ship hulls, and replacement for dissipated galvanic systems, large condenser water boxes, reinforcing steel in concrete, bare or poorly coated structures, unisolated structures and water storage tank interiors. 

Austenitic irons are used for valve and pump bodies condenser water boxes in refineries, cryogenics, marine and electricity generation systems. In general austenitic irons have better corrosion resistance than unalloyed or low-alloy irons. 

Platinized anodes are used in marine work on ships, hulls, and for applications involving the interior parts of structures such as condenser water boxes, internal parts of pumps, certain pipeline interiors. 

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