... filler material,offers good sealability for various condition; Gasket seal___Graphite spiral wound gasket: Uses expanded graphite tape as the filler material , which provides ... : low carbon steel, 304, 316, 316L, etc.C. Nonmetal belt: flexible graphite, tailor-made graphite, PTFE and asbestos paper. Graphite spiral wound gasket(gasket seal, spiral ...