SCALEGUARD® Tube Sheet Insulator

PVI's patented tube sheet insulator protects against metallurgical failure that can result from scale buildup in the water heater. SCALEGUARD keeps the temperature of the tube sheet below the critical ductile-to-brittle transition temperature by separating it from the heat of combustion. Because the tubesheet is used only as a structural surface and not as a heat transfer surface, scale buildup on the waterside has no heat trapping (and hence damaging) effect. In addition, because it's not a heat transfer surface, a buildup of scale on the tube sheet's waterside will not reduce thermal efficiency. (A few additional firetubes compensate for the heating surface lost by insulating the tube sheet).

U.S. patent 4,936,260