2.5.1 Wafer (UHMWPE)
Sealing material (UHMWPE wafer)
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Sealing of plastic pipe joints and metal flanges to plastic components requires skills, knowledge and
experience. Special requirements may apply, depending on the piping system in which the wafer is
installed. When you are not familiar with the necessary procedures, please consult the responsible person
for the original design of the piping system.
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Non-gasket sealing
UHMWPE flanges may be sealed without sealing material. The “memory” of pipe-grade UHMWPE makes
it an ideal flange face sealing surface. It becomes its own “gasket flange”, and seals well when un-marred
and torqued to meet or exceed the UHMWPE seating stress. When properly torqued, the joint between
the wafer (UMMWPE) and the mating flange becomes self-sealing.
Using this method, the specified seating torque needs to be applied, followed by a mandatory re-torque
applied 4-hours to 24-hours after completion of the initial torque application. See following table for the
torque to be used. Note that this is a torque table for 150 LBS flanges with a UHMWPE wafer.
Gasket sealing
The second method, (with gasket), uses a low gasket seating bolt torque, applied to a soft elastomeric
gasket, for lower pressure applications (like landfill gas collection or use with torque-limited PVC or
fiberglass flanges), followed by the mandatory re-torque 4 hours to 24-hours after the initial torque.
Gasket material maybe either foamed PTFE, like Gylon, or an elastomer. For rubber lined pipes, additional
gaskets are not recommended.
Bolting pattern and torque
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UNNECESSARY OVER TORQUING WILL DAMAGE THE WAFER.
Threads should be clean and well lubricated. Actual field conditions may require variations in these
recommendations.
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