Available in sizes from 2-12 inch
design, TFE-lined Weco« butterfly valves assure positive control of
acids, caustics, esters and other corrosives.
The TFE-lined Weco« butterfly valve is a chemical-resistant valve
suited for the CPI's most corrosive services. All
"wetted" parts are completely lined with a high-density virgin
TFE for protected flow control over long life. This TFE
polytetrafluoroethylene polymer has better chemical resistance than all
other fluorocarbon polymers.
Three valves models are available in sizes 2-inch through
12-inch. All are non-directional and self-centering between 125 lb
or 150 lb. ANSI flanges. They will provide drop-tight
service from 1 mm. absolute to 175 psi and at temperatures from -20║ F
to 250║ F. Long neck body styles are available to clear as much
as 3 inches of pipe insulation.
TFE polymer is applied to the 17-4 PH stainless steel disc core in a
compression molding encapsulation process which eliminates porosity and
hairline cracks common to other TFE bonding processes. Minimum
Teflon thickness ranges from 3/32 inch on the 2-inch disk to 7/32 inch
on the 12-inch disk. The thinner disc of extra tough 17-4 PH
stainless steel results in a streamlined profile after TFE
The disc is self-centering between a two-piece stem, with a broached
hex drive to eliminate troublesome in-line pins and screws while
providing positive disc movement.
A precision molding process is used to inject and bond a
resilient EPT elastomer between the TFE liner and a two-piece phenolic
backup. The thickness of TFE on the seat is held at 1/16 inch to
give adequate ware resistance while maintaining the flexibility
necessary to provide drop-tight sealing under all rated conditions.
Leakage at the flanges is eliminated by four concentric rings
integrally molded on each face of the seat. This seal is secure
even if three of the rings are damaged during installation or
maintenance. No gaskets are required between valves and flanges.
Corresponding flat surfaces at the top and bottom of the seat mate
with corresponding flats around the steam recesses on the disc to
provide a primary sealing surface. The "floating disc"
design of Weco« butterfly valves assures the long-life effectiveness of
this primary seal.
The standard body is cast iron. Optional materials include
ductile iron, steel, bronze, 316 stainless steel and aluminum.
For superior external corrosion resistance and for sanitary
applications, the body may be coated with tough, non-peeling,
acid-resistant, white Nylon II. This coating has been approved by
the USDA, Consumer and Marketing Service, as acceptable from a toxicity
and extractability standpoint.