Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

418 Centrifugal Pumps: Design and Application
Figure 17-57. Corrosion of a mating ring surface exposed to the product being
sealed,
fully. Most seal manufacturers have a wealth of information on materials
for various services and should be contacted for their recommendations
on the best materials to be used.
Finally, when a seal has been properly selected and installed, it will
result in years of trouble-free operation. The seal shown in Figure 17-58
has been in service for 220,000 hours or just over 25 years. This 3-inch
seal was used to seal gasoline, fuel oil, and occasionally, propane. Normal
operating pressure and temperature were 800 psig and 60 °F. The
shaft speed was 3560 rpm. The condition of the carbon primary ring exhibits
virtually no adverse wear of the sealing face or at the drive
notches, which represent the drive system on this seal. V\fear at the carbon
seal face is only 0.032 inches for this period of time. The mating ring
appears to be in good condition after running for this length of time. It is
reported that this seal had not been leaking even though some minor heat
checking had occurred. The seal aged in service; the O-ring hardness increased
from 70 to 90 durometer. This would eventually lead to a loss of
flexibility for the seal head.
A checklist for identifying causes of seal leakage is found in Table
17-6. Many other references on causes of seal leakage are available from
seal manufacturers. One such source is found in Identifying Causes of
Seal Leakage, Chart and Bulletin S-2031, available from John Crane Inc.