Control Valve Packing
PTFE V-Ring
Minimum friction.
Packing lubrication not required.
Resistant to most known chemicals except molten alkali metals.
Recommended temperature limits: −40 to +450_F (−40 to +232_C)
Not suitable for nuclear service because PTFE is easily destroyed by radiation.
Laminated and Filament Graphite
Suitable for high temperature nuclear service or where low chloride content is
desirable (Grade GTN).
Provides leak-free operation, high thermal conductivity, and long service life, but
produces high stem friction and resultant hysteresis.
Impervious to most hard-to-handle fluids and high radiation.
Suitable temperature range: Cryogenic temperatures to 1200_F (649_C)
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 which result from
process equipment leaks. Strict government regulations, developed by the US, dictate
leak detection and repair programs (LDAR). Valves and pumps have been identified as
key sources of fugitive emissions.
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.
Packing systems designed for extremely low leakage requirements also extend packing-
seal life and performance to support an annual monitoring objective. The ENVIRO-SEAL
packing system is one example. Its enhanced seals incorporate four key design
principles. These are the containment of the pliable seal material through an anti-
extrusion component, proper alignment of the valve stem or shaft within the bonnet bore,
applying a constant packing stress through belleville springs and minimizing the number
of seal rings to reduce consolidation, friction, and thermal expansion.
Single PTFE V-Ring Packing : The single PTFE V-ring arrangement uses a coil spring
between the packing and packing follower. It meets the 100 ppmv criteria, assuming that
the pressure does not exceed 20.7 bar (300 psi) and the temperature is between −18_C
and 93_C (0_F and 200_F). It offers very good sealing performance with the lowest
operating friction.
ENVIRO-SEAL_ PTFE Packing : The ENVIRO-SEAL PTFE packing system is an
advanced packing method that utilizes a compact, live-load spring design suited to
environmental applications up to 51.7 bar and 232_C (750 psi and 450_F). While it most
typically is thought of as an emission reducing packing system, ENVIROSEAL PTFE
packing is suited also to non-environmental applications involving high temperatures
and pressures, yielding the benefit of longer, ongoing service life.
ENVIRO-SEAL Duplex Packing: This special packing system provides the capabilities
of both PTFE and graphite components to yield a low friction, low emission, fire-tested
solution (API Standard 589) for applications with process temperatures up to 232_C
(450_F).
KALREZ_ Packing: The KALREZ pressure/temperature limits referenced are for Fisher
valve applications only. KALREZ with PTFE is suited to environmental use up to 24.1 bar
and 204_C (350 psi and 400_F) and to some non-environmental services up to 103 bar
(1500 psi). KALREZ with ZYMAXX, which is a carbon fiber-reinforced TFE, is suited to
260_C (500 F) service.
ENVIRO-SEAL_ Graphite ULF: This packing system is designed primarily for
environmental applications at temperatures in excess of 232_C (450_F). The patented
ULF packing system incorporates very thin PTFE layers inside the packing rings as well
as thing PTFE washers on each side of the packing rings. This strategic placement of
PTFE minimizes control problems, reduces friction, promotes sealing and extends the
cycle life of the packing set.
HIGH-SEAL_ Graphite ULF: Identical to the ENVIRO-SEAL graphite ULF packing
system below the packing follower, the HIGH-SEAL system utilizes heavy-duty, large
diameter Belleville springs. These springs provide additional follower travel and can be
calibrated with a load scale for a visual indication of packing load and wear.
ENVIRO-SEAL_ Graphite for Rotary Valves: ENVIRO-SEAL graphite packing is
designed for environmental applications from −6_C to 316_C (20_F to 600_F) or for
those applications where fire safety is a concern. It can be used with pressures to 103
bar (1500 psi) and still satisfy the 500 ppmv EPA leakage criteria.
Graphite Ribbon for Rotary Valves : Graphite ribbon packing is designed for non-
environmental applications that span a wide temperature range from −198_C to 538_C
(−325_F to 1000_F).
