BLACKTIGHT™ - VALQUA® No. 6590 Series. These gaskets are composed of pure graphite (expanded graphite) as filler material. Features: Reducing retightening frequency, Excellent air tightness, Excellent sealing properties at very low temperatures. Temperature: -270 to 450oC / -454 to 842oF, Pressure: Max 30.0 MPa. Suitable fluids: General fluids (water, oil, etc.), high temperature & high pressure steam, liquefied gas, cryogenic fluid