It is the aim of this catalog to present our customers with clear, direct, and relative information about our products. We trust this information will be of service to them when in the market for flange isolation components, and that our products will offer them a simple solution for their corrosion conditions. To slow the accelerated process of corrosion, our products meet the highest requirements for materials. This adds long-term value and offers a life-cycle cost benefit.

Insulation and the Galvanic Cell Although sometimes considered a form of corrosion, galvanic corrosion is more accurately a type of corrosion mechanism because galvanic action is the basis for, or can accelerate the effects of, other forms of corrosion. Uniform attack, pitting, and crevice corrosion can all be exacerbated by galvanic conditions. Galvanic corrosion occurs when two dissimilar conducting materials are in electrical contact. It usually consists of two dissimilar conductors in electrical contact with each other and with a common conducting fluid (an electrolyte), or it may occur when two similar conductors come in contact with each other via dissimilar electrolytes. When two materials are in electrical contact and connected by an electrolyte, a galvanic current flows between the two. This electrically coupled system is known as a galvanic cell. Flange insulation kits provide dielectric insulation by insulating the two materials from one another. The kits consist of an insulating gasket, bolt sleeves, nonmetallic washers, and backing washers. An insulating washer must be used under the head of the bolt and the nut to provide full dielectric insulation.

Isolation and the Cathodic Protection System A correctly designed cathodic protection (CP) system effectively prevents corrosion. One critical element in any CP system is dielectric isolation of the protected structure. Dielectric isolation eliminates the possibility of protective current from the CP system being conducted to buried metallic structures other than the one being protected. Dielectric isolation also helps to control or eliminate the potentially severe and localized damage caused by stray-current corrosion. Stray currents are those that leave a protected structure rather than returning along the structure lead or wire connected to an anode. Flange Isolation Kits provide dielectric isolation by isolating the flanged joint relative to its location it the CP. The kits consist of an isolating gasket, bolt sleeves, nonmetallic washers, and backing washers. An isolating washer may be used under the head of the bolt and the nut, or on just one side making sure to leave the open side open to the cathodic protection system.

Westermann BG


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