example, an on/off valve operated only a
few times a year is easier to keep leak-tight than a control valve whose stem is
constantly in motion.
A good source of information on fugi-
tive emissions control is the EPA docu-
ment “Leak Detection and Repair—A
Best Practices Guide.”
possible human errors associated with
repair and maintenance.
SIS REGULATIONS
Valves used in safety instrumented systems must be qualified to IEC61508,
“Functional safety of electrical/electron-ic/programmable electronic safety-related systems” (from the International
Electrotechnical Commission, the standards body for all electrical, electronic
and related technologies).
valve, sleeved plug valve and wedge plug
valve are good choices.
In SIS applications, a higher-rated
(higher SIL) valve may be preferable to a
lower-rated one. For example, an SIL 2-
rated system can use SIL 1-rated valves
if they are installed in pairs, in a so-called 1 out of two (1oo2) configuration,
in which failure will not occur unless both
valves fail to operate on demand. A single
SIL 2-rated valve may well cost less (and
be simpler to install and maintain) than a
pair of SIL 1 valves.
FINDING THE RIGHT
EQUIPMENT
The choice of equipment for a process
plant has great influence on safety, so
given the critical role that valves typically play in processing, selection of the
right valves is critical to that safety. For
shut-off services, the high performance
butterfly valve, high performance ball
The High
Performance
Butterfly Valve
The high performance butterfly valve
(HPBV) offers a
closed-bottom
design that eliminates potential leak
paths. Additionally,
the HPBV uses a double-packed stem
seal to provide an extra line of defense
against fugitive emissions. The valve also
has a long life expectancy, which reduces
The High
Performance Ball
Valve
High performance
ball valves are available with soft seats
for nonabrasive service at normal temperatures, and with hard
seats for cryogenic or
high-temperature
applications, including fire-safe applications. They also are available with live-loaded packing to reduce fugitive emissions. For use in High Integrity Pressure
Protection Systems (HIPPS) to SIL- 3, a
trunnion design is often preferred
because it keeps the ball aligned, reduces
seal leakage and provides minimum
pressure loss in the piping system.
U.S. ALLOYS, INC
Since 1976, Round Bar Supplier for Valve & Fitting Manufacturers
of
Petrochemical / Power Generation / Nuclear / Aerospace
Round Bar Stock
GRADES:
(Domestic and Import)
A105
A350 LF2
SA105
A675 GR 70
A696 GR C
SIZES:
304/304L
316/316L
317/317L
321/321H
347/347H
F- 11
;;;; 9(/9;;; 9
1. ( 9(/9; ; - ; (; 9; ; ; ; 9; 99; ; ; 96 9
ASTM/ASME/(Latest editions)
NACE MR01-75/NACE MR0103
DIN 3. 1.B/EN 10204
Phone (713) 644-1983 Fax (713) 644-9889 www.usalloys.cc
The Sleeved
Plug Valve
The sleeved plug
valve (SPV) is a
non-lubricated,
quarter-turn
valve that
achieves sealing
through the use of a compression sleeve
that acts as the sealing component. The
SPV is designed to be economical, flexible and compact while providing a
secure, long-lasting, in-line seal. The
SPV features superior sealing, ease of
adjustment and dual steam seals. Other
recognized benefits are no seizing or
sticking, economical fugitive emissions
control and contamination-free operation. The sleeved plug valve has multiple
features that make it among the safest
options on the market. It does not need
lubrication, and its extended service life
and high reliability rating minimize
down time. A unique benefit from this
valve is the absence of leak paths or cavities where materials or residue can
accumulate—limited accumulations
present fewer opportunities for erosion
and leaks, resulting in reduced maintenance. The valve also is double-seal protected, which provides added leakage
protection.
