Fiber-filled coupling layer

Caution. Lead is an electrically conductive material. The designer should be careful not to place carbon brick and/or carbon-filled mortar in contact with or very close to lead linings where the service includes an electrolyte in solution, as lead and carbon will form a galvanic couple, with the carbon as anode and the lead cathodic. This will result in the wasting of the lead. If carbon brick or carbon-filled mortars are to be employed in the same design, an electrical insulating barrier should be placed between them and the lead. Such barriers may be Teflon or other fluorocarbon sheet, a thick layer of a carbon-free, chemically inert mortar, or a thick layer of ceramic or organic fiber. 

---