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Control Valves
Scroll Down for Technical Information on
Control Valves
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Samson
Controls:
YOUR
PARTNER FOR SUCCESS
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SAMSON
has formed affiliations with a series of companies also active in the
field of valve engineering, but specializing in the production of
different valves from those manufactured at SAMSON’s facilities. The
specialization ranges from simple forged ball valves to advanced bypass
valves for steam turbines in nuclear power stations. With the assistance
of these associated companies, SAMSON is able to offer engineered
solutions from a single source to comply with the requirements of
complex projects and to meet unusual control challenges.
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Do you have a Control Valve requirement
or require technical advice? Make the "experts"
Samson Controls your first call.
Control Valve Selection and Design
Control Valve Selection and Design
Information from Samson
Controls
Samson
Controls - Technical Information - Some great information
from our valued sponsor Samson
Controls
12.11Control
Valve Design Aspects for Critical Applications in Petrochemical Plants -
Holger Siemers - With three decades of experience in demanding applications, Mr
Siemers has a deep appreciation of developments and trends in sizing control
valves. In this paper, he reviews the past, present and future of valve design
and sizing, taking all-important issues such as increasing cost pressure and
time pressure into account. This paper is presented in two parts: firstly, how
to use manufacturer independent software to analyse given or calculated plant
parameters in more detail from an overall pointof view with a complete power
check and optimizing possibilities. Some case studies are also discussed. The
second section, scheduled for a future issue, includes information on to design,
size and use severe service control valves with good performance for long
maintenance intervals. Different philosophies of valve design (plug design),
pressure balance systems, stem sealing, actuator sizing, cost philosophies
for" high end" applications are discussed. The paper covers:
Accurate sizing & software tools
Energy saving by plant and valve optimization
Debottlenecking: Can the old valve do the new job ?
Predictable troubles with control valve sizing in case of sub-critical flow
conditions and in case of flashing.
Control valve failures & troubleshooting.
The hidden valve enemy: Critical outlet velocities need to take priority.
Fugitive emissions philosophies for control valves.
Actuator sizing philosophies.
Control valve design and cost philosophies for "high end"
applications.
Plant
Design and Control Valve Selection under Increasing Cost and Time Pressure, Part
1 - Holger Siemers - Following a career spanning three
decades, Mr Siemers is well aware of the pitfalls to be avoided when specifying
control valves for a range of demanding applications. In his latest paper for
Valve World, he looks further into plant design and control valve selection when
working under increased time and cost pressure. This article is split into two
parts: broadly speaking, part one looks at control valve operating points and
provides a case history involving a mismatch. The author then introduces better
valve sizing practices and uses this theory to resolve the problems introduced
in the case history.
Plant
Design and Control Valve Selection under Increasing Cost and Time Pressure, Part
2 - Holger Siemers - Part two starts by explaining the
trends and definitions of inherent valve characteristics before focusing on
"quick and dirty“ sizing. The paper then addresses cavitation before
concluding with the expert software available to help select the optimum valve
characteristic form - thanks to Samson Controls, Conval and Valve
World .
12.11
Bellows
Sealed Valve Technology - Maintenance-free,
hysteresis-free bellows seals guarantee zero leakage over the entire service
life of the control valve. With Samson's environmentally friendly bellows seals,
you are always on the safe side and plant downtime required to replace the valve
packing is a thing of the past.
Enhanced
Reliability for Final Elements - Process valves,
sometimes also addressed as final elements are in many cases the most decisive
factor when it comes to calculating the SIL level for a safety instrumented
function (SIF). Due to the large variety of conditions of usage in the process
industry there is a lack of appropriate data and approved devices. Testing
procedures like partial stroke testing can provide enhanced diagnostic coverage
and therefore help to get improved reliability data for the total loop.
Verification of this 'diagnostic data' and proper integration of these
procedures into the safety instrumented system (SIS) and basic process control
system (BPCS) environment at the same time poses a challenge. New developments
on actors and relevant approvals are presented as well as instrumentation with
new functionality to support diagnostic coverage, different topologies for
connection to SIS and BPCS are discussed - thanks to SA
Instrumentation and Control
12.11Fugitive
Emissions Philosophies for Control Valves -Holger Siemers
- It is interesting to compare the use of the bellows seal design versus low
emission packing material. The bellows seal design seems to have been forgotten
in international discussions and published papers, but it is still unbeatable as
regards its life cycle and 'quality of tightness'. In the 'world of valves'
under the requirements of fugitive emissions approximately 5% are control valves
- thanks to SA
Instrumentation and Control
Other Control Valve Selection and Design
Links
The Fisher Control Valve Handbook- This superb 295-page PDF whitepaper is a
control valve resource that has been consistently updated for 30 years. It
contains vital information on control valve performance and latest technologies.
Thanks to Emerson Process
Management
Valve
Materials of Construction for NACE Applications - Technical information from
Metso
Automation
The Plant Maintenance Resource Center has some very useful links on Control
Valves including;|
Control
Valve Actuator Operating Modes - Details on fail safe conditions, fail
closed and fail open.
Control
Valve Concepts - Control Valves Do What They Are Told!
Control
Valve Flow Characteristics - Trim design will affect how the valve capacity
changes as the valve moves through its complete travel. Because of the variation
in trim design, many valves are not linear in nature. The relationship between
valve capacity and valve travel is known as the flow characteristic of the
valve. Valve trims are specially designed, or characterized, in order to meet
the large variety of control application needs. This is necessary because most
control loops have some inherent nonlinearities, which you can compensate for
when selecting control valve trim.
Control
Valve Packing - Packing is a sealing system which normally consists of a
deformable material such as TFE, graphite, asbestos, Kalrez, etc. Usually the
material is in the form of solid or split rings contained in a packing box.
Packing material is compressed to provide an effective pressure seal between the
fluid in the valve body and the outside atmosphere.
Control
Valve Seat Leakage Classifications - There are actually six different seat
leakage classifications as defined by ANSI/FCI 70-2-1976. But for the most part
you will be concerned with just two of them: CLASS IV and CLASS VI. CLASS IV is
also known as METAL TO METAL. It is the kind of leakage rate you can expect from
a valve with a metal plug and metal seat. CLASS VI is known as a SOFT SEAT
classification. SOFT SEAT VALVES are those where either the plug or seat or both
are made from some kind of composition material such as Teflon.
Control
Valve Terminology - A comprehensive terminology list.
Control
Valve Tips & Tricks - An excellent list of useful tips and tricks for
the control valve user.
Control
Valves - Flow Recovery Coefficient
Control
Valves - Pressure Recovery Factor
Selecting a Control Valve- Fluid
velocity in a control valve is a key parameter that must be considered when
sizing and selecting a control valve. High fluid velocities can lead to erosion
damage, trim wear, trim component failure, vibration and high noise levels.
Therefore, it is vital to design for valve velocities within acceptable limits
so that these problems are avoided. This paper addresses these issues - from Masoneilan.
Looking
Inside the Valve- Asher Glaun - Modern control valves can monitor pressure
and flow control in a full range of specialist process industries. Now, even
better prediction of a valve's performance can be calculated and it is possible
to find out what is really going on inside a valve - from Masoneilan
Fluid
Velocity Considerations - by Jospeh Shahda, Senior
Applications Engineer, Masoneilan Operations- from Masoneilan
Why
most Control Valves today are Throttling at around 60% opening.- from Masoneilan|
Fluid
Kinetic Energy as a Selection Criteria for Control Valves -by Herbert L.
Miller and Laurence R. Stratton - Reproduced with the permission of CCI Sulzer
Valves
Selecting
HVAC Control Valves- from Siemens Building Technologies, Inc.
Your
Best Bet in Control Valves - Hans Bauman - Control valves may be the most
important, but sometimes the most neglected, part of a control loop. The reason
is usually the instrument engineer’s unfamiliarity with the facets,
terminologies, and areas of engineering disciplines, such as fluid mechanics,
metallurgy, noise control, and piping and vessel design that can be involved
depending on the severity of service conditions - From ISA and InTech.
Determine
the Characteristic Curve of an Installed Control Valve - Jeff Sines - The
performance of a control valve is defined by its inherent and installed
characteristic curves. The inherent characteristic curve is a plot of the
percent of valve opening vs. the percent of maximum flow coefficient (CV). The
inherent characteristic curve is determined by measuring the flow rate at
various positions of valve travel with a fixed differential pressure across the
valve (typically 1 psid) and calculating the CV at each position using a form of
the generalized Control Valve CV equation - From Engineered Software.
Smart
Valves and Online Monitoring Improve Operations - A
predictive maintenance program is the basis for overall process and control
optimization. A key tool is the installation of on-line condition monitoring
systems on valves. The improved insight into the condition of valves can lead to
a total overall increase in quality and a decrease in process upsets and
breakdowns - from Metso
Automation
Smart
Valves, Positioners and Flow Conditioning Technology - One of the newer
devices that offer improved performance of control valves is the smart
positioner. A smart positioner is a microprocessor-based electronic positioner
that derives benefit from digital programming to obtain improved positioning
performance. Some models offer predictive maintenance and diagnostic benefits as
well. An advantage of the smart positioner is that it may be programmed to use a
position control algorithm to achieve better dynamic response than standard
pneumatic positioners.-
from Masoneilan
Evaluation of
Control Valve Performance is Necessary in Plant Betterment Programs - Sanjay
V. Sherikar - Reproduced with the permission of CCI Sulzer Valves
12.11Fugitive
Emissions and Control Valves - This paper describes the history of the
development of the fugitive emissions requests, the standards committees and
manufactures reactions to them. How do these standards differ? How do they
compare? The paper also describes the approach and issues a control valves
manufacturer has to deal with to meet the various requirements on fugitive
emissions. It is recognised also that control valves by their function of
continuous movement have more tendency to wear out than on/off valves and are
therefore more easily subject to packing leakage - from www.valve-world.net
A
Valve as a Flowmeter - Because valves are already installed for
process control, process optimization and performance can be further improved by
using control valves to measure the flow rate - Technical information from Metso
Automation.
Cavitation and Flashing in Control Valves
Cavitation and Flashing information from Samson
Controls
Cavitation
in Control Valves -
Cavitation can arise in hydrodynamic flows when the pressure drops.
This effect is regarded to be a destructive phenomenon for the
most part. In addition to pump rotors, control valves are particularly exposed
to this problem since the static pressure at the vena
contracta even at moderate operating conditions can
reach levels sufficient for cavitation to start
occurring in liquids. The consequences for a
control valve as well as for the entire control process vary
and are often destructive causing: Loud noise,
Strong vibrations in the affected sections of the plant,
Choked flow caused by vapour formation, Change
of fluid properties, Erosion of valve components,
Destruction of the control valve and Plant
shutdown.
12.11Control
Valves for Critical Applications - Know the Causes of Cavitation and Flashing
and How to Prevent Them - J. Kiesbauer - In refineries,
the process media flowing through valves are primarily liquids. With liquids,
critical operating conditions caused by cavitation or flashing may occur.
Symptoms are, for instance, increased noise emission, valve and pipe component
erosion or low-frequency mechanical vibration in the valve and the connected
pipeline. Under these conditions, in particular, neglecting details can result
in negative influences on plant performance and costs of ownership.
Unfortunately, common practice today is to select control valves in a “quick
and dirty” fashion, because the phases of planning, bidding and order
processing are connected with significant pressures of cost and time. This
article presents the basic principles underlying these problems and shows how to
eliminate them based on practical examples from refineries. Moreover, a new
throttling element is introduced, that is especially suited to reducing noise
emission produced by cavitation. This new throttling element is being
implemented in refineries with increasing success.
Other Control Valve Cavitation Links
Control
Valve Cavitation, Damage Control - James A. Stares - This paper outlines the
application methods used by leading control valve manufacturers to avoid the
damaging effect of cavitation on control valve performance and reliability -
from Masoneilan.
Calibration
and Verification of Cavitation testing facilities using an orifice-by
William Rahmeyer and Fred Cain
This is ICEweb's Technical Information page on Control and Quarter Turn Valve
Actuators
Butterfly Control Valves
Why
a Butterfly- Vinod Bhasin -thanks to Sigma Tech- This is a pretty old
document but has some good information.
Control Valve Sizing
Valve Sizing Information from Samson
Controls
General
information
Demo
version
Update to
current version
Other Control Valve Sizing Links
Sizing
Control Valves-This article defines a more standard procedure for sizing a
valve as well as helping to select the appropriate type - From
cheresources.com.
Valve
Sizing and Selection - Sizing flow valves is a science with many rules of
thumb that few people agree on. This article covers a more standard
procedure for sizing a valve as well as helping to select the appropriate type
of valve. From cheresources.com.
Nelprof
Control Valve Sizing and Selection Software -Apply for the CD from
Metso Automation
Masoneilan
Control Valve Sizing Handbook- from Masoneilan
Split Range Control Valves
Implementing
MPC to Reduce Variability by Optimizing Control Valve Response- Ever had a
problem with split range valves, this paper may just help! Thanks to www.controlglobal.com
and our sponsor Emerson
Process Management
Control Valve Applications
Samson
Controls have a wealth of knowledge on control valve applications
including;
12.11Cryogenic
Valve Technology - The valve that came out of the
cold - Do you get the shivers everytime you have to select a valve for cold box
applications? Cool down... with SAMSON's Type 3248 Cryogenic Valve, temperatures
down to -320 °F (-196 °C) will be covered. With an extended isolating section,
the actuation and accessories are protected from catching a cold.
Other Control Valve Applications Links
The following links are from Metso
Automation
Control
and Automated Valve Solutions for the Oil and Gas Industry
Control
Valves for Heater Bypass applications
Technical
Bulletins
- Control Valve Application Information which covers a wide range of
Paper, Chemical, ESD, Oil and Gas and Refinery applications.
The following links are from Masoneilan
Avoid
Control Valve Application Problems with Physics-based Models -Kinetic energy
criteria have many limitations- from Masoneilan
-This article explores the rationale for KE
limitations and demonstrates that KE criteria often provide very rough
approximations of the actual physical phenomena that cause valve problems.
Boiler
Feedpump Recirculation Valves
Condensate
Pump Recirculation Valve
De-Aerator
Level Control
Natural
Gas Storage- Valve Solutions-by Larry Swartz
Getting
Optimum Performance through Feedwater Control Valve Modifications -by Brian
Leimkuehler and Sanjay V. Sherikar - Reproduced with the permission of CCI
Sulzer Valves.
The
Application of Control Valves to Compressor Anti-surge Systems - E.W.Singleton
- Pipelines
transporting gases and vapours are invariably dependent on centrifugal or
turbo-compressors for the propulsion of these fluids. Under normal operation,
with
the compressor running at any constant speed there is a specific relationship
between
the pressure head across the compressor and the flow through it. But this
stable
relationship can be disturbed by sudden changes in flow, pressure and density,
usually
caused by sudden variations in demand downstream of the compressor or in the
case
of systems requiring multiple compressors a disturbance can be caused by the
switching of compressors in and out of service. All these can give rise to
formidable
pulsations of pressure and flow, better known as a surge. Under surge
conditions the
compressor may run erratically and a situation can arise where the pressure
build up
in the downstream pipe may overcome the delivery pressure of the compressor
resulting in a flow reversal, reversing the compressor and causing mechanical
damage - from Koso Kent Introl.
12.11
Control
Valves for Pump Protection (Recirculation) Service
- E.W.Singleton - This paper
discusses the essential procedures involved in the application of control valves
for the protection of pumps operating at low flow conditions. Automatic
Recirculating Valves (ARC Valves), although they do not fall into the category
of control valves, do play an important role in pump protection, so a reference
to these is also included -
from Koso Kent Introl and Valve
World.
Control Valve Noise Calculation and Prediction
12.11
Control
Valve Exit Noise and its use to Determine Minimum Acceptable Valve Size -
Alan H. Glenn - This paper describes general aerodynamic noise generation and
prediction and, in more detail, the IEC 60534-8-3 exit noise prediction. It will
describe noise generation inside the valve and at its exit, its propagation down
the pipeline, and its transmission through the pipe wall and into the outside
environment. Several sample cases are included. A simple computer program that
could be used to facilitate the calculation of the control valve exit noise for
control valves is also briefly explained - from Flowserve and Valve
World.
Valve
Noise Prediction verses Velocity Head Limitations in Gas Applications-Joseph
Shahda - Principal Engineer Masoneilan -from Masoneilan
In recent years, the control valve industry has seen an important debate about
the validity of limiting the valve trim exit velocity head to a maximum of 480
kPa in gas and steam applications. This velocity limitation is assumed to
provide an acceptable noise level and avoid problems that arise in control valve
gas and steam applications. However, in a very large number of applications,
adopting a velocity limiting approach may require the use of expensive
multi-stage or multi-turn trim designs. This article
demonstrates that low noise levels can be achieved without following this overly
conservative and expensive trim exit velocity head limitation. It also
highlights that having a trim exit velocity head lower than 480 kPa will still
generate a very high valve noise level if the valve outlet Mach number is high.
Masoneilan
Noise Control Manual-from Masoneilan
- This 24 page manual provides comprehensive informative material regarding
noise in general and control valve noise in particular. It covers Control
Valve Noise, Aerodynamic Noise Prediction, Aerodynamic Control Valve Noise
Reduction, Atmospheric Vent Systems, Hydrodynamic Noise and Installation
Considerations.
Improving
prediction of Control valve noise-from Masoneilan
Understanding
IEC Aerodynamic Noise Prediction for Control Valves from our valued
sponsor Emerson Process
Management
Flow
Component and Control valve Research -Utah State University. It
includes
Control
Valve Testing Procedures and Equations for Liquid Flows
The Dynamic
Testing of Check Valves.
Application
of Butterfly Valves for Free Discharge, Minimum Pressure Drop, and for Choking
Cavitation
Control Valve Maintenance
How
to achieve optimal Control Valve Performance - Shawn Anderson and Neal
Rinehart. - Leaders in the process industries realise that good process control
performance is an essential element in achieving world-class reliability as well
as optimizing overall process efficiency. Since control valves are the only
devices in the process loop that actually “move” to adjust the process,
their performance is critical. The best way to achieve excellent performance is
to initially select the most appropriate final control valve for the application
and then to maintain its performance over time -from our valued sponsor Emerson
Process Management
Rethink
your Control Valve Maintenance - Neal Rinehart - Learn how new diagnostic
tools can help make predictive maintenance a reality - Far too little has been
done over the years to sustain the performance of control valves once they go
into operation, despite widespread agreement on the impact that valves have on
process efficiency. Rather than considering control valves as assets to be
preserved, too many plants treat them as liabilities — frequently replacing
critical valves during shutdown for no reason other than length of service. As a
result, millions of dollars have been wasted and perfectly good control valves
often have been discarded - from our valued sponsor Emerson
Process Management
Valve
Wellness Programs - David W. Douglas - To maximize the utility of diagnostic
equipment used in chemical processing, technicians must stretch their knowledge
of control valves and related diagnostic equipment that keeps tabs on valve
health and safety. Thanks to plantservices.com.
Improving
Valve Life and Operating Efficiency The Easy Way - John C. Robertson -
Valves are, unquestionably, the most important part of any piping and pumping
system because they direct the flow of fluids and regulate temperatures.
Properly used and maintained, they can improve process efficiency and lower
costs. It is wise to apply the basics of proper valve maintenance in ways that
improve their life cycle and operating efficiency. Here are eight
often-overlooked valve maintenance basics that can help you do just that. From
maintenanceresources.com.
Improving Valve Life and Operating Efficiency The Easy Way - John C.
Robertson - Eight often-overlooked valve maintenance basics.
Use
of Ultrasonic Analysis in the Testing of Isolating Valves - Offshore
installations use a series of isolation valves to divert the flows from the
various pumps. One of the main reasons a pump test can "fail", is if
the isolating valves are passing. This article describes testing the isolating
valves using ultrasonic analysis. Overhaul of an isolating valve costs
significantly less than undertaking an unnecessary pump major overhaul.
Control Valve Positioners
Control Valve Positioner Information from Samson
Controls
Intrinsic
Safety and Flameproof Enclosure - An Impossible Team in Explosion Protection?
- Dipl.-Ing Guido König and Prof. Dr.-Ing. Heinfried
Hoffmann - The increasing application of digital field devices in process
automation has revived the discussion about the best types of protection for
instrumentation used in hazardous areas. The large number of electrical
components integrated in microprocessor based devices requires more precautions
to be taken per field device in order to ensure explosion protection. A
positioner designed for pneumatically operated control valves is used to
demonstrate different solutions.
Selection
and Application of Positioners, Limit Switches, Solenoid Valves and Other
Accessories
Diagnostic
Tools for Control Valves - Dr. Jörg Kiesbauer - Digital
positioners offer interesting features regarding improved process plant
reliability and maintenance or servicing. This could provide the basis for using
software tools for early fault diagnosis and performance visualization of
control valves with extended functions. These tools can completely preserve the
control valve 's condition when new. It can be subjected to trend analyses as
well as to preventative maintenance and servicing while in operation. This
article describes these possibilities based on an example of such a new
diagnostic tool.
Hybrid
Positioner Technology - An all-around talent - In
SAMSON's Series 3730 Positioners, everything revolves around just one rotary
pushbutton: turn to select parameters, press to activate them. The large display
is your window to the system. Alternatively, you can easily configure the
positioner from a PC.
Other Control Valve Positioner Links
Doing
Business Differently-Digital Positioners-from Masoneilan
The Next Generation of Smarter Valves part
1 and part 2
- By Béla
Lipták, thanks to ControlGlobal.com
Smart
Technologies Sustain Plant Reliability, Help Control Costs - Todd Gordon -
This article highlights the benefits of DVC technologies in a power plant - from
Emerson
Process Management.
Positioner
and Actuator Operating Modes - The terms "direct" and
"reverse" are frequently used when discussing control valves,
positioners, and controllers. While the definitions of direct and reverse seem
pretty straightforward, they cause quite a bit of confusion - especially when
split-ranging is done. From The
Plant Maintenance Resource Center.
The
Wireless Option - Harcros Chemicals Rethinks Its Position on Valve Positioning -
Kurtis Jensen, Kevin Root & Lloyd Hale - From the
outside, a chemical plant may look like a series of pipes, tanks, and railcars.
However, within these plants, there are many valves that are employed to move
liquids throughout the chemical production process. Some of these valves may be
operated manually, which, generally speaking, increases the chance that they may
be left in a position that is unwanted. In such a scenario, it would be
advantageous to have some automated valve monitoring capability to ensure the
appropriate positioning of valves in real-time. However, the complexity of hard
wiring such valves is cost-prohibitive. Hence, the evolution of industrial
wireless systems has opened up new opportunities for valve positioning
applications in the chemical processing industry - from www.flowcontrolnetwork.com
8.11
Mission
Possible - Analog-to-Digital Valve Upgrades - Sandro Esposito -
A transformation is underway in process control, as a wide variety of new
digital devices have been introduced in recent years, and a growing number of
facilities have installed them. The transition is still a work in progress,
however. Some process control facilities have simply been a bit slower to adopt
digital valve positioners, for example, as they seek to become more comfortable
with this unfamiliar technology. Others have made the switch to digital devices,
but have maintained an “analog mindset” and use the digital positioners as
they did their analog predecessors. The status quo is maintained and
technologies that could help plant operators save time, money and frustration
while potentially improving product quality and enhancing safety, are either not
adopted or are underutilized. The first step in making the transition to digital
valve positioners is understanding how they can be easily and cost-effectively
implemented in a facility. This article will begin to bridge that gap by
reviewing the various technologies available and highlighting the steps that
should be taken to help ensure a successful transition. In addition, it will
explain how plant operators can achieve what many consider to be a “mission
impossible” – i.e., “hot cutover,” or switching to a digital valve
positioner while the process workflow continues uninterrupted - from Kentrol and
Flow Control.
Valve Positioners - Some general but useful information on valve positioners
- from maintenanceresources.com.
Self Operated Regulators
Self Operated Regulator Information from Samson
Controls
Introduction to
Self-operated Regulators
Control valve design aspects for critical applications in petrochemical
plants - Part
1, Part
2 and Part
3 - thanks to Samson
Controls, Conval
and Valve World .
This is an excellent paper in three parts which covers Control Valve Design and
Sizing.
Temperature
Regulators - The characteristic feature of self-operated
temperature regulators is their compact design, including a sensor, a valve and
a capillary tube. Their simple operating principle is based on fundamental
mechanical, physical and thermodynamic laws.
ICEweb's comprehensive page on ESD and BDV valves contains a
super vault of technical papers on this important subject.
Looking for a valve without corrosion problems? These valves
made from plastics and potentially using Nanotechnology techniques may just
solve them.
These valves are specific to those power plant issues such as
de-superheaters, steam service etc.