says Flowers, it operates at 5 to 10%
open. Operating that close to the seat,
especially with high-pressure drops in
hydrocarbon service, tears up the trim,
he says. If the situation is bad enough
and if the pressure drop is high enough,
the valve may be bouncing off the seat,
which not only harms the valve but creates process control issues, he explains.
Sometimes, Flowers says, misapplication is the fault of the customer, who may
decide that for a 6-inch pipe he simply
must have a 6-inch valve. Most often,
this results because of a group’s consecutive thinking. “The process engineer
comes out with certain service conditions, and then it goes to the engineering
firm, who adds a safety factor,” he
explains. “And then it’ll come to the valve
manufacturer, and typically we’ll add a
safety factor. So when it actually gets
installed in the field …you’ve got two or
three safety factors on top of the actual
service conditions,” he adds.
And other ways to get poor control
exist besides specifying the wrong-size
valve. If the distributed control system
(DCS) is mistuned, the situation gets out
One factor that can make
things tough for a valve
has nothing to do with the
media or the pressure
drop, but with a simple
mistake—specifying a
control valve that’s too
large for the application.
of hand pretty quickly. “With proper
DCS programming,” Steinke says, “you
can probably work around a control valve
problem.” But, he adds, “you also have
to recognize that typical DCS responses
are dramatically faster, in many cases,
than your control valve response. So
unless you have a properly operating con-
trol valve, you’re driving a stagecoach
pulled by wild horses with rubber band
reins. You will not be able to function and
control the valve.”
There’s still another way that misap-
plication can damage a valve, Steinke
continues. An example is an application
in which the work a valve is called upon
to do has quietly increased without valve
specifiers realizing it. He cites as an
example the recycle valve in a water
flood system. “It has to not only open to
protect the pump and not damage the
pump because of inadequate flow during
the initial startup, but once you start
transferring load and flow to the field
… that valve now has to go into a con-
tinuous duty recycle mode to load-bal-
ance the plant,” he says. A valve that
was designed for intermittent pump
recycle duty now has to operate continu-
ously. “There’s a tremendous difference
between qualifying a control valve for
an intermittent pump recycle on a clean
water power plant loop versus a 365-
day-a-year operation recycle flow in a
water flood program: time and duration,
corrosivity, solids in the flow stream,”
he says.
THE WAIT IS OVER!
The North American
Catalog of Valves
A sourcebook for buyers of
valves, actuators and controls
There’s no better place to locate U.S. and Canadian sources for valves, actuators and controls
than the North American Catalog of Valves, now in its 9th edition. This 52-page resource
contains:
• Detailed information on 75 different companies, including how to contact the company,
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• A handy product matrix so you can see which of 40 different products types each
company manufactures.
• A number of useful articles on topics such as valve specifications, the criteria for selecting
valves, the various applications in which valves are used and more!
WHAT’S AHEAD
So what can we look forward to? Steinke
predicts increased demand for process
control on these severe service pieces of
equipment. He also anticipates more
requirements for safety integrity levels
(SILs) “being implemented into the control loops and analysis of hardware and
equipment as compared to simple safety
relief.” And, he concludes, we’re likely to
see future demands for fugitive emission
requirements.
James looks at alternate energy as
both an opportunity and a challenge for
valve manufacturers. Synthetic fuels are
being made from solid materials such as
coal and biomass, he points out. The
challenge is that: “if you thought erosive
stuff was erosive before, that industry is a
whole other level.”
The opportunity comes from the fact
that many of the companies developing
alternate energy sources are not oil com-
panies. Not only will next-generation
equipment require new valve technology,
he says, it will require more involvement
with the end user and more educational
efforts by valve makers. “I think there
will be more change in this industry in
the next 10 years than probably hap-
pened in the last 50,” he concludes. VM
To order a copy of the Valve Catalog, visit The VMA Store on www.VMA.org.
Cost: $29.95 ($24.95 for VMA/VRC members) + shipping/handling.
PETER CLEAVELAND, a contributing editor to
Valve Magazine, writes extensively about issues
related to the flow control industry. Reach him
at pcleaveland@earthlink.net.
