Drywell Sump Pump Flanges

Problem

A vegetable fiber gasket on the drywell sump pump flanges failed at a BWR Nuclear Plant in New York. Repair of the equipment requires that unit be taken off-line; therefore leakage failure is not tolerable. Vegetable fiber gaskets are susceptible to weeping and inflexible. Application details of the drywell sump pump flange:

Temperature: 115 deg F
Pressure: 40 PSI
Size: 4 INCH
Some pipe misalignment exists

Solution

The solution was to use a Garlock Multi-Swell 3760 gasket which is highly compressible, seals at low bolt loads, and conforms well to less than perfect flanges.