SUMMARY
Defective, improperly installed, or inadequately
maintained tube fittings are a source of fugitive emissions
and economic losses in industrial plants. The purpose of this
study was to determine the prevalence and magnitude of leaks
from tube fittings in industrial gas service.
Measurements were made on operating units
in 11 industrial plants in the Baton Rouge area. Over 4000
fittings were tested, and the leak rates from 498 ports in
504 leaking fittings were measured. The vast majority of the
fittings were on instrument air lines.
We found that, overall, 12.1 percent of
the fittings tested and 10.0 percent of the ports tested were
leaking. The average leak rate was 494 ml/min (1.74 x 10-2
CFM). The largest leak rate was 40,900 ml/min (1.44
CFM). There was no correlation between leak rate and internal
pressure.
The distribution of leak rates was very
skewed toward small values; 52 percent of the leaking fittings
had a leak rate less than 1 ml/min, and 87 percent of the
leaking fittings had a leak rate less than the average value.
The procedures used in the present study
were identical to those used in a study we reported in 1981.
On the average, both the prevalence and magnitude of the leaks
were found to be lower in the present (1998) study. Also,
in contrast to the 1981 results, the percentage of leaking
fittings was found, in the present study, to be plant specific.
The 11 plants in the 1998 study fell into three distinct groups
classified according to the percentage of leaking fittings
found. |
lsu.edu 
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