Construction and Measured Properties

SIGMA 588 is a multi-layer cellular sheet made from unfilled PTFE. The layers are bonded through direct sintering without adhesives, unlike envelope gaskets. According to Flexitallic testing, it exhibits 55% compressibility, 24% recovery, and a density of 1.1 g/cm³. For a 1.5 mm thickness, the brochure states an ASME m-factor of 1.4, a seating stress (y) of 11 MPa, and an EN 13555 Qmin/0.01 of 16 MPa. ASTM F38 creep relaxation is reported at less than 50%. These parameters are derived from specific test methods and do not serve as universal assembly criteria.

Applications and Service Conditions

The published high compressibility of 55% makes this design particularly suitable for damaged, glass-lined, or bolt-load-sensitive flanges. The manufacturer also specifies concentrated acids and alkalis, subject to chemical compatibility. The technical literature states ratings up to 260°C and maximum pressure limits of 85 bar at 1.5 mm, 80 bar at 2 mm, and 75 bar at 3 mm. These maximum limits must never be combined without consulting the P/T curve.

Comparing Without Assuming Equivalence

Evaluate flange surface irregularities, thickness, and creep resistance against GYLON 3545/3565 or Durlon 9645. Their construction is not identical, despite targeting similar fragile flange applications. To prepare an engineering review, please specify the media, concentration, flange class, available bolt torque, and required thickness.

Other technical data sheets to review: Garlock GYLON 3565 and Garlock GYLON 3545. These provide structural design comparisons.