Epoxy-coated steels

Galvanised steel provides increased corrosion resistance in carbonated concrete. In concrete with more than 0.4% chloride ion with respect to the cement content, there is an increased risk of corrosion and at high chloride contents the rate of corrosion approaches that of plain carbon steel. In test conditions the rate of corrosion is greater in the presence of sodium chloride than calcium chloride. Fusion-bonded epoxy-coated steel performs well in chloride-contaminated concrete up to about 3.9% chloride ion in content. 

Treadaway, K. W. J., Davies, H. and Brown B. L., Performance of fusion bonded epoxy coated steel reinforcement. Proceedings of the Institute of Structural Engineers (in press)... 

Module casing Field membrane Epoxy-coated steel FRP Epoxy-coated steel and FRP... 

The storage and transfer of raw chemicals requires special considerations relative to the equipment that come into contact with epoxy resins. Carbon steel is generally satisfactory for pipe and tank construction and will not rust beneath the epoxy resin. Rust occuring above the level of the epoxy and accidentally introduced into the resin may be removed by filters. Epoxy coated steel pipe, aluminum or stainless steel pipe, or epoxy fiberglass composite tubing is used to prevent rusting downstream of the filter. 

In the hollow flne-flber design, the hollow fibers are a bundle of thousands of parallel, self-supporting, hair-like fibers enclosed in a fiberglass or epoxy-coated steel vessel. Water is introduced into the hollow bores of the fibers under pressure. The permeate water exits through one or more module ports. The concentrate also exits in a separate one or more module ports, depending on the design. All these module designs may be combined into banks of modules and may be connected in parallel or in series. 

Module casing Epoxy-coated steel FBP Epoxy-coated ... 

As noted above, externally wound tubular membrane elements are fabricated primarily of extruded ABS tubing (natural), cellu-loslc or blend membranes and dacron paper. The cartridge assembly designed to house the membrane elements and provide for the uniform dlstrlbutlon/flow of feed stock is fabricated of extruded thin walled polystyrene headers. Pressure vessels were fabricated either by using epoxy coated steel pipe or fiberglass vessels. 

In recent years there have been very serious cases of corrosion damage in some structures in tropical areas where severe attack of epoxy-coated steel has been observed only a few years after construction. This situation has led contractors and designers to reconsider the widespread use of this technique on structures exposed to chloride-bearing environments [47]. Serious doubts have been expressed about whether epoxy coatings, even in the absence of any damage, can insure long-lasting protection in heavily chloride contaminated and hot environments, particularly when the concrete is frequently wetted [48,49]. 

S. R. Yeomans, M. P. Novak, "Further studies of the comparative properties and behaviour of galvanized and epoxy coated steel reinforcement , International Lead Zinc Research Organization (ILZRO) project ZE-341, Progress report... 

Some of the reinforcing steel bar alloys are cold-worked steel epoxy-coated steel 30400 stainless steel 30453 stainless 31600 stainless 31653 stainless Duplex S31803. Table 5.9 shows the corrosion resistance of some steels. 

Lempton, R. D. Jr., and Schemberger, D. 1996. Improving the Performance of Fusion-Bonded Epoxy Coated Steel Reinforcing Bars, CORROSION 96, Paper No. 323, NACE International, Conferences... 

Figure 17 Electrochemical impedance data (Bode plots) for epoxy-coated steel as a function of immersion time in 0.5 N NaCl solution. (From Ref. 98.)...

Since the maximum voltage that can be generated with zinc anodes is extremely unlikely to generate hydrogen embritdement, galvanic systems have been used to protect prestressed concrete members. They are also used on fusion bonded epoxy coated steel reinforced piles as the effects of electrical discontinuity between bars is unlikely to lead to significant stray current induced corrosion as the currents and potentials are low. 

Ramniceanu, A., Weyers, R.E., Anderson-Cook, C. and Brown, M.C. (2006). Measuring the Field Corrosion Activity of Bridge Decks Built with Bare and Epoxy Coated Steel. Journal of ASTM International. 

ASTM A775-81. Standard Specification for Epoxy-coated Steel Reinforcing Bars, American Society for Testing Materials. 

Fusion-bonded epoxy-coated steel performs well in chloride-contaminated concrete up to about 3.9<7o chloride ion in content. 

Walkways are fabricated with FRP grating. All concrete surfaces in the cell room are constructed with fusion-bonded epoxy coated steel reinforcing bars, and Type V... 

At the moment we can use bare steel, epoxy coated steel, or... 

Zinc-coated steel is increasingly used in situations that otherwise would be too aggressive to steel. Five-year trials in the agricultural industry, particularly in animal waste environments, showed (Kim, 1991) the superior corrosion resistance of galvanizing after fabrication, compared to epoxy-coated steel. 

Yeomans, S. R. (1991). Investigations of galvanized and epoxy coated steel reinforcement in concrete. I6th Int. Galv. Conf., EGGA, London, GBl/1-5. 

Rebars are polymer fibre reinforced-concrete composites, and they are used as primary structures. It is estimated that replacement of steel reinforcing bars by non-corrosive polymer fibres, i.e., by Kevlar or carbon fibres (which gives rise to Kevlar or C-composite bars) for concrete structures produces structures with one-quarter the weight and twice the tensile strength of the steel bar. It is known that, corrosion of steel reinforcement from carbonation or chloride attack can lead to loss of the structural integrity of concrete structures, and such a danger is non-existent for rebars. Thermal expansion coefficient (TEC) values of these fibres are closer to concrete than that of steel, which provides an another advantage and they have the same surface deformation patterns as the steel bars. In addition, they can provide more economy than epoxy-coated steel bars. 

The most popnilar coating for reinfoieing bars is fusion bonded epoxy. Epoxy-coated steel is addressed in ASTM A 775M,... 

Transportation Research Board Annual Meeting, 1993, Taped Oral Session on Epoxy-Coated Steel Reinforcement, Washington, DC, January 1993, available from Transportation Research Board, National Research Council, Washington, DC. 

Figure 8>15. Temperature-dependence of the diffusion of oxygen in epoxy-coated steel (175 pm) after 73 days in seawater measured as cathodic current density at -700 mV SCE (after Steinsmo and Bardal, 1987).

Shao, Y, C. Jia, G. Meng, T. Zhang, and F. Wang, The role of a zinc phosphate pigment in the corrosion of scratched epoxy-coated steel. Corrosion Science, 51, 2009, 371. 

The XPS survey spectra from the failure of the bond between epoxy-coated steel and nylon. The upper two spectra are characteristic of the epoxy coating while the lower are typical of nylon. This shows that the two distinct failure regions both exhibit cohesive failure but in the epoxy lacquer (near to the epoxy steel interface) or the nylon (near to the epoxy nylon interface)... 

Various techniques such as optical and electron microscopy, IR-ATR ESCA and SIMS have been used for failure mode analysis in polymeric adhesive joints. However, these techniques are not amenable for in situ, non-destructive examination of the failure surfaces as failure occurs. In order to develop in situ techniques, UV reflection and fluorescence methods are evaluated, as they can be applied via optical fibres to the actual failure surface. Failure surfaces of two types of adhesive joints are examined by UV reflection and fluorescence, complemented by FT-IR ATR studies. The first joint studied is PU on epoxy-coated steel. The second is PETP/PE/PETP. 8 refs. 

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