The original Twin Seal led to the rigid requirements of double block and bleed service and resulted in the
market leading Twin Seal valve. The patented Twin Seal valve is a non-lubricated, resilient seal,
expanding plug-type valve which has a mechanical means of freeing the plug before it is rotated from
the closed to open position. The plug and seal slips rotate freely, with no seal to body contact,
eliminating seal abrasion and wear. The unique, dove-tailed design plug is operated inward between
the slips, mechanically wedging out the seal slips for a positive upstream and downstream
shut-off. This creates a positive, mechanical shut-off of each valve port independent of springs,
system pressure or flow. In addition, the primary seals are reinforced by a secondary metal-tometal
seal, resulting in a superior, fire-safe design. Seals may be repaired with common tools
while the valve is in-line, after the line has been depressurized and drained.
