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FRM-22.1 Rev.G
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NOTE: Th is optional confi guration will not allow the user to control the backpressure independent
of the pressure between the seals. Pressure may be introduced between the seals without increasing
the backpressure on the plug. However, any positive-pressure-diff erential between the backpressure
and the pressure between the seals will cause the
Check Valve
to open and allow the fl uid and pressure
behind the seals into the area between the seals. For example, if the pressure between the seals is at 50 psi
and the vessel generates a back pressure of 100 psi then the check will open and balance the two zones
thereby elevating the pressure between the seals to 100 psi. Th is confi guration is intended only to pump
cooling water through the plug to help slow the heat transfer through the pipe in order to help preserve
the front seal closest to the weld.
Figure 7: Fill and drain ports on the plug
FILL PORT
RETURN \ DRAIN
PORT
