Reference Manual

1−12
Figure 1-22. Measurement Frequency for Valves
Controlling Volatile Organic Chemicals (VOC)
B2566
Laminated and Filament Graphite
D Suitable for high temperature nuclear service
or where low chloride content is desirable (Grade
GTN).
D Provides leak-free operation, high thermal
conductivity, and long service life, but produces
high stem friction and resultant hysteresis.
D Impervious to most hard-to-handle fluids and
high radiation.
D Suitable temperature range: Cryogenic
temperatures to 1200°F (649°C).
D Lubrication not required, but an extension
bonnet or steel yoke should be used when packing
box temperature exceeds 800°F (427°C).
USA Regulatory Requirements for
Fugitive Emissions
Fugitive emissions are non-point source volatile
organic emissions that result from process
equipment leaks. Equipment leaks in the United
States have been estimated at over 400 million
pounds per year. Strict government regulations,
developed by the US, dictate Leak Detection and
Repair (LDAR) programs. Valves and pumps have
been identified as key sources of fugitive
emissions. In the case of valves, this is the
leakage to atmosphere due to packing seal or
gasket failures.
The LDAR programs require industry to monitor all
valves (control and noncontrol) at an interval that
is determined by the percentage of valves found to
be leaking above a threshold level of 500 ppmv
(some cities use a 100 ppmv criteria). This
leakage level is so slight you cannot see or hear it.
The use of sophisticated portable monitoring
equipment is required for detection. Detection
occurs by sniffing the valve packing area for
leakage using an Environmental Protection
Agency (EPA) protocol. This is a costly and
burdensome process for industry.
The regulations do allow for the extension of the
monitoring period for up to one year if the facility
can demonstrate an extremely low ongoing
percentage of leaking valves (less than 0.5% of
the total valve population). The opportunity to
extend the measurement frequency is shown in
figure 1-22.
Packing systems designed for extremely low
leakage requirements also extend packing seal life
and performance to support an annual monitoring
objective. The ENVIRO-SEALt packing system is
one example. Its enhanced seals incorporate four
key design principles including:
D Containment of the pliable seal material
through an anti-extrusion component.