JAMES Walker’s Supagraf Furnasele graphite-based gaskets, originally developed to seal blast furnace ducts, are now available in diameters from 500mm to over 2m.
They can be custom designed to solve sealing problems in different industries where large conformable one-piece gaskets are needed to effectively and reliably handle high temperature gases, especially on vertical flange faces.
Ideal for sealing warped or uneven flanges and low bolting loads, these robust gaskets comprise a supporting metal ring with a relatively thick layer of graphite bonded to both faces.
Circular gaskets are the most common, but virtually any shape can be produced, including very complex profiles, and the only size limitation is the ability to transport it to site says James Walker.
Two basic variants are a 3mm thick steel ring with 2mm thick graphite layers, generally suitable for gaskets with overall diameters of 1m or more; and a 2mm thick steel ring with 1.5mm graphite layers mainly for diameters under 1m.
Other thickness combinations can be produced. Face widths are usually in the range of 40mm to 50mm.
Units are usually made for installation inside the flange bolt circle, but can also be supplied with full-face profile and bolt holes or with slot-legs for locating on two or more bolts. Lifting lugs or handles may be fitted to the larger gaskets.
The gasket's metal layer is generally made from hot-rolled carbon steel. Stainless steel is readily available and more exotic alloys such as Monel, Inconel and Incoloy can be supplied by James Walker on request.
For particularly hot operating flanges, an additional inner gasket of mineral wool material can be supplied as a thermal barrier to prevent oxidation of the graphite by hot gases. This is unnecessary for many installations where large valves are water cooled, such as in steelworks.
Typical applications of the Supagraf Furnasele gaskets include areas operating at high temperatures, but relatively low pressures, such as in hot air ducts and blast furnaces, which often have large diameter flanges with low bolting loads.