Corrosion specimen rack

Figure 6. Typical corrosion specimen rack for Phase II pilot plant exposures...

For the sake of consistency, a terminology has developed within the atmospheric corrosion testing community with respect to testing. The test facility itself is commonly referred to as a corrosion yard. Racks, commonly fabricated from pipe or wood, are installed to hold the fixtures for the individual test specimens. The latter are referred to as "frames," and can be fabricated from wood or metal (nickel-copper alloy, stainless steel, aluminum, etc.). These frames are usually designed to hold approximately 75 specimens, isolated from each other and the test frame by porcelain, plastic, or rubber insulators." Thus, a corrosion yard... 

ASTM G 4 Standard Method for Conducting Corrosion Coupon Tests in Plant Equipment Provides guidelines for in-plant testing— weight loss coupons, specimen racks, reporting. 

The specimens should be mounted so that they are insulated from their supporting racks and from each other. Such insulation can be achieved by the use of fastening assemblies, such as illustrated in Fig. 19.33. Occasional difficulties have been encountered with this sort of assembly for tests of copper and high-copper alloys because of deposition of copper from corrosion products along the surfaces of the insulating tubes which provided a... 

Portable deposit/corrosion monitors are typically housed in an enclosure of perhaps 30 in. H x 20 in. W x 15 in. D. Components include inlet flow controller, strainer, adjustable electric heater, (outer) see-through glass housing, (inner) heated specimen tube or block, hot/cold temperature readout, corrosion rack, plus thermal overload, low-flow cut-off, and other safety devices. The specimen tubes or blocks are available in different metals (as are the corrosion coupons) and can usually be replaced in a matter of minutes. Unlike test heat exchangers, the cooling water in this type of monitor flows on the shell side of the specimen tube. 

A typical rack employed for installation of specimens in pilot plants is shown in Fig. 6. Both corrosion coupons, 2 X 1 X 0.35 in. thick, and bend specimens intended to determine stress-corrosion cracking susceptibility, are included in the installation for aqueous corrosion testing. Specimens are separated by high density alumina spacers to eliminate electrochemical effects. During exposure, the racks are welded to existing components in the pilot plant equipment. 

In 1996 the IAEA initiated a CRP on the corrosion of aluminium clad spent research reactor fuels to help evaluate the state of the spent fuel assemblies and to inform pool/basin operators regarding maintenance and housekeeping procedures to extend the lives of the FAs. The main activities of this programme are related to exposing racks of aluminium alloy specimens (coupons) in different spent fuel basins around the world. Five racks were suspended in the 1EA-R1 reactor pool and were subsequently withdrawn after different time spans to evaluate the extent of corrosion of the coupons as a function of alloy composition, crevices, bimetallic effects and water chemistry. During this period the pool water was monitored for pH, conductivity, chloride ion content and radiometry (Table 6.3). The IAEA CRP racks are denoted as racks 1,2A, 2B, 3A and 3B. 

Atmospheric exposure consists of placing specimens such as coupons, parts, components, on racks at stationary test sites [53]. The example in Fig. 7 shows bumpers imder test at the marine splash and spray facility of the LaQue Center for Corrosion Technology at Wrightsville Beach, North Carolina. The nature of the site varies depending on geographic area and specific location within an area. Factors such as environmental chemistry (chlorides, pollutants. 

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