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The Following links are compliments of our valued sponsor Metso Automation
ESD
Valve Selection Guide - General ESD Valve Definition - This
14 page document is an excellent Reference - Covers SIS Standards,
Specifications, Valves, Actuators, Safety Valve Testing, Materials, Fire
Protection, Safety Integrity Level (SIL), Total Life Cycle, Applications,
Quality Assurance and Terminology.
Partial
Closing with Neles Valveguard - Safety
engineers throughout the world are struggling with the problem of how to best
comply with new and more stringent safety requirements. New IEC requirements
state that manufacturers must determine and document precise levels of safety
and furnish quantifiable proof of compliance. In light of these requirements, BP
feels it is necessary to reassess its traditional safety loop testing
procedures. In particular, BP feels it is important to improve its safety valve
testing procedures in order to drive costs down and improve plant safety.
Neles
ValvGuard "exercises"
to Keep Fit
- Mark Williamson - An ESD valve, whose
mechanism is not often moved, is susceptible to jamming - There is a
need to test valves frequently but (with older technology) this is only possible
when the process is stopped for major turnarounds, or process shutdowns. Today,
the periods between shutdowns is becoming longer and longer. To ensure
compliance with safety standards, maintenance engineers therefore face a
dilemma. They need more valve testing but they have fewer opportunities to do it
when the process is down. Also, frequent manual testing carries a high labour
cost. This can be overcomes by automatically “exercising” the valve through
a partial stroke at pre-programmed intervals.
Ensuring
that your ESD Valves Work when needed - Emergency
Shut-Down valves (ESD) are critical in protection of plant and personnel. These
must operate in the event of plant malfunction or fire. The most important
requirement for an ESD valve is it’s reliability of operation (open or close)
in an emergency. By it’s very nature, it is difficult to test that an ESD
valve is "available" without causing a plant upset. The plant is at
risk however unless it can be shown that the valve is functioning properly. How
can this be done?
Need
a Cryogenic Valve Testing Facility? - The
cryogenic valve test centre at Metso Helsinki factory is one of the largest and
most advanced dedicated valve test facilities in Europe. It offers customer
inspectors the possibility of witnessing potentially hazardous testing
operations through shockproof windows in the comfort of a protected, air
controlled control room built to the latest safety standards, using a fully
computer controlled and logged testing system.
Reducing
Operating Costs on ESD valves - As safety standards
become more stringent, online testing will become part of everyday life for
process plants that want to increase time between shutdowns. However, with
frequent manual online testing comes high operational cost.Neles ValvGuard™ is
uniquely designed to lower operating costs and deliver fast payback. When
purchases are made quite often only the initial capital outlay is considered.
Whilst the price of Neles ValvGuard compares favourably with other types of
partial stroke testing device, the savings that are made during the operational
life of the valve go far beyond the initial expenditure. Savings can be expected
in several important areas.
Comparison
Between Testing Methodologies to achieve the required SIL level. -
The IEC 61508/61511 (Equiv. ISA - S.91 (TR.84)) safety standards are creating
more stringent testing requirements for safety equipment. It is clear from
existing data (OREDA – Offshore Reliability Data book) that the largest
proportion of undetected failures are due to the Final Element. Sensor
technology has already integrated ‘smart’ principles for some time. Common
failure modes such as plugged lines can be detected by noise signal analysis.
The safety system itself has developed to a level where it has both redundancy
and a high level of diagnostic coverage. Therefore, that leaves us with the ‘Final
Element’.
Acoustic
Leak Detection - Acoustic techniques are being
employed to detect leakage. It is known that leakage is usually accompanied by
acoustic emission. An acoustic emission is a sound wave, or more properly, a
stress wave that travels through a material as the result of some sudden release
of strain energy. The acoustic energy travels in for of ultrasonic waves through
the material of the structure. Thus it may be detected by a remote sensor
situated either on the containing structure or in the fluid itself.
Diagnostic
coverage Reports for ESD valves - Metso Automation
has developed Neles ValvGuard™ a partial stroke testing system for emergency
shutdown valves and emergency vent valves. In addition to providing the normal
safety shutdown function, the system performs automated diagnostic partial
stroke tests, which can be programmed by a configuration software (FieldCare)
installed on a PC. Various test parameters are measured and recorded during
these diagnostic tests. If test parameter limits are exceeded, the valve will
alert the operators so that investigative action can be taken. In addition,
these test parameters can be trended to create a history of the valve
performance and deterioration of valve performance can be detected and
evaluated.
Gas
to Flare System ESV & ESD Valves - Both ESD
and ESV valves are commonly located in or near the process plant. The flows from
different processes are further lead to a flare header which is sized for the
certain worst-case volume condition, assuming that relief devices discharge at
the same time and other process vents may also be flowing.
Atmospheric
Distillation ESD Valves - Atmospheric distillation is the
first major process in a refinery. All crude oil entering the refinery, after
desalting, passes through the atmospheric distillation column on it’s way to
further processing in down stream process units. If there is a shut down of the
atmospheric distillation column it means that the entire rerfinery is
essentially shut down. The ESD valves are located at the bottom of the
atmospheric distillation column and are typically arranged as two valves in
parallel piping. The fluid passing through the valves is refered to as heavy
bottoms. This fluid is the heaviest cut of a hydrocarbon attainable by
atmospheric distillation. The heavy bottoms pass through the ESD valves on their
way to the vacuum distillation column for further processing. The ESD valves are
used in the normally open condition and are expected to function reliably
throughout long process runs, typically four (4) to five (5) years between shut
downs.
Oil
Refinery and Other Units Processing Hydrocarbons - ESD valves with High
Integrity Level - There are fire and explosion
risks in the units processing flammable hydrocarbons in case the fluid comes in
contact with the atmosphere. If there are high- and low-pressure sections in the
plants like e.g. in refinery HDS (hydro desulphurisation) units, the
low-pressure side has to be protected against high pressure in case of control
failure. Traditionally the number of emergency shut-off valves (ESD) in the
process lines in a refinery is not very high. With Neles ValvGuard’s partial
stroke testing functionality the ESD valves are automatically diagnosed for
their operability while the plant is in operation. With this technology general
plant safety can be improved in a cost effective way.
Reliable
ESD Valves in Tower Bottom Lines in Heavy Oil Units -
Besides fired heaters, the distillation tower bottom areas are the most
fire-risky places in a refinery. When the question is of residual oils, high oil
temperature, coke formation, sulphur corrosion and possible particles in the oil
make the conditions even more severe. Neles metal-seated ball valve with its
constructional features and the Neles ValvGuard, partial stroke testing system,
used to keep the valves under continuous watch are helping to minimize the fire
risks in these areas.
What
You Need To Know About Safety Instrumented Systems (SIS) and Partial-Stroke
Testing of ESD Valves - A useful document providing an
overview of SIS and Partial stroke testing.
The
Value of Safety Valves - Juha Yli -Petä ys - Safety
valves are the most important components in the safety loop (sensor, safety
logic and final element), because most of the problems that occur are related to
the functionality of the final element. It is important to remember that these
elements are moving mechanical devices, which operate in very difficult
environmental conditions. This makes the need for regular valve testing and for
testing while the process is running absolutely essential.
Increased
Reliability and Safety at Czech Refinery through Partnership in Valve
Maintenance - Karel Dvorak and Niko Aunio- In the past,
Česká Rafinérská’s strategy has been to carry out turnarounds every
four years. This was the first time that the interval was extended to 5 years.
After 9 years of operation, some problems were expected, however, on this
occasion Česká Rafinérská’s approach was different from that adopted
for the previous turnaround. The control valve scope was reduced and the on/off
valve scope increased to include overhaul testing based on the SIL
classifications. The Metso field survey and Neles ND9000 diagnostics formed the
basis for the valve turnaround planning.
10.11Taking
Safety Valve Testing to the Next Level - Juha Kivelä -
Today’s safety engineers face increasing challenges every day. Safety
requirements are becoming more and more demanding, while the global market
situation is simultaneously creating constant pressure to reduce costs. The
IEC61511 safety standard requirements state that industrial processing plants
must determine the Safety Integrity Level (SIL) for all the different areas of
the plant. Based on the area SIL classifications, the plants must then be able
to dispatch quantifiable proof of compliance with the requirements.
10.11
Bringing
Intelligence to On-Off valves and Simplifying On-Off Valve Instrumentation
- Juha Kivelä - Traditionally, on-off valves have been instrumented by at least
a separate solenoid valve and limit switches. Quite often the desired
functionality cannot be achieved by using only a solenoid valve and limit
switches, which means that additional pneumatic accessories are needed. For
example, if the process requires precise valve opening or closing stroke times,
these cannot be guaranteed by using only a solenoid valve; but there is also a
need for some extra accessories such as throttle valves.
10.11Onshore
Condition Monitoring of Offshore Valve Assemblies - Niklas Lindfors and
Jarkko Räty - Especially in the offshore sector, there is strong emphasis on
minimizing the number of staff working in hazardous offshore environments,
without impacting on reliability. At the same time, it is expected that the
availability of production and the life cycle costs of process equipment should
be optimised. These requirements create the need to improve the capability to
analyse control-valve data from offshore applications - to focus and plan
service actions well in advance. In other words, to enhance the utilization of
existing technologies and increase the use of specialist know-how in order to
enable offshore personnel to carry out the required tasks effectively, safely
and with minimal labour and disturbance to the process itself. (Go to page 4 to
access this information)
11.11Valves/Actuator
Combinations - Rens Wolters - In 2010 a new revision of the
IEC 61508 was formally published. The previous version dated back to 1998 and
since then it is used in the Oil and Gas industry for over-pressure protection
systems. This paper focuses on the modifications in the IEC 61508 related to the
final elements and as example an application in the Oil and Gas industry is used
- from Mokveld and TUV.
The Following links are compliments of ICEweb sponsor Emerson Process Management.
Verifying
the operation of ESD valves -
The operation of many industrial processes involves
inherent risk. Instrumented Protection Systems are specifically designed to
reduce the severity of the impact of an emergency event. These systems, such as
Safety Instrumented Systems (SIS) and others, are designed to monitor a process
for potentially dangerous conditions. During an emergency event, the SIS
activates the valve to move the process to a safe state. What
happens if the valve does not move when an emergency event occurs? Personnel
safety, equipment damage, and environmental protection could be at serious risk.
Smart
Positioners in Safety Instrumented Systems - Riyaz
Ali and LeRoy Jero - A review of the way microprocessor-based digital valve
controllers – otherwise “smart positioners” – can improve the
capabilities of safety systems in detecting potential risks and heading them off
before they become a danger.
Smart
Positioners to Predict Health of ESD Valves - Riyaz Ali
and Dr. William Goble - Safety Instrumented Systems (SIS) involve final control
elements such
as emergency shutdown valves, emergency venting valves, emergency isolation
valves, etc. These valves are not continually moving like a typical control
valve, but are normally expected to remain static in one position and then
reliably operate only when an emergency situation arises. Valves which remain in
one position for long periods of time are subject to becoming stuck in that
position and may not operate when needed. This could result in a dangerous
condition leading to an explosion, fire, and/or a leak of lethal chemicals and
gases to the environment.
Predicting
Health of Final Control Element of Safety Instrumented System by Digital Valve
Controller - Riyaz Ali -
This paper will discuss testing final control element of SIF loop, on-line,
while plant is running, by using smart positioners to perform partial stroke
test to detect dangerous failures, which would have remain undetected, if
testing were not done.
4.11
Process
ESD Systems - This power point presentation is a large
9.48 Mb download but contains some really useful information on ESD systems and
ESD Valves - from ICEweb sponsor Emerson
Process Management and Centralian Controls.
The Following links are compliments of ICEweb sponsor Samson Controls.
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). 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.
Other Links
Assessment
of Valve Failures in the Offshore Oil & Gas Sector - John Peters
- This comprehensive report describes the findings of an assessment study
of data-set information regarding valve problems in the UK Offshore Oil &
Gas Industry. It was undertaken by the National Engineering Laboratory, on
behalf of the Offshore Division of Health & Safety Executive, as part of a
wider initiative to reduce hydrocarbon releases. From the UK HSE.
Emergency
Shutdown Valve Study - Industry Operating Experiences and Views; The Way
Forward- John Peters - An older study but still very relevant. From the UK HSE.
Partial
Stroking on Fast Acting Applications-Willem-Jan
Nuis, Rens Wolters - Partial stroking: This is a widely used method to
avoid sticking of a ball valve when it is not operated for some time. It is also
used to reduce the actuator size and thus the total cost of the valve +
actuator. From safetyusersgroup.com.|
Double
Whammy: The benefits of Valve Signatures and Partial Stroke Testing -by Paul
Gruhn and
Derek Essam - Many papers have been written over the past five years on
the benefits of partial stroke valve testing (see refs1-6). There are many
techniques for performing such testing, most of which are mentioned in the draft
ISA technical report TR84.0.03. Partial stroke valve testing is one of the most
effective techniques for enabling a single valve to achieve high SIL
performance. One aspect of testing, however, has not been covered – that of
valve signatures.-Thanks to Valve World
Need
for an industry standard for ESD valves from an engineering and safety
point of view -Meghdut Manna - Tahakum East -Since the Piper Alpha
disaster in the North Sea, design of ESD valves has been given top priority and
remains to be of great concern for plant safety management. Constant
improvements have been made to ensure the integrity of the ESD valves.
Essentially, ESD valves should perform their duty (usually closure of valves)
under plant demand condition. To meet the production bottom-line, these valves
are required to remain open for months, even years, which leads to build up or
corrosion in the valve internals. Final control element is the weakest link in
the SIS. From the safety users group.
9.10
The
Striking Role of Partial Valve Stroke Testing to meet Safety Integrity Levels
- Bert Knegtering - Partial Valve Stroke Testing or PVST, is a concept to
automatically increase the performance of Safety Instrumented Systems. PVST is a
concept where safety-related valves like ESD valves and shut-off valves are
automatically tested concerning failure modes that are related to valve sticking
and slowing down operation. Current trends in the industry show an upcoming
number of dedicated technical PVST solutions by various automation and
instrumentation vendors. The added value of PVST within the process industries
is a significant reduction of the frequency of required manual periodic valve
proof tests, its related manual test cost and reduced spurious trips due to
manual errors. Partial testing is performed by additional automated test
instrumentation, which can easily be initiated and controlled by the
safety-instrumented systems’ logic solver such as the safety-related PLC. This
paper discusses practical examples of Partial Valve Stroke Testing in which it
appears that SIL 1 rated valves can be upgraded to SIL 2, and off-line proof
test intervals which can be extended from 2 to 5 years. Thanks to Honeywell and www.safetyusersgroup.com
Firesafe Actuators
- An essential part of equipment safety is to be able to maintain the
fail-safe position when a fire breaks out. In case of pneumatic linear
actuators, the fail-safe position must be assumed and maintained when air supply
fails or the diaphragm ruptures. Usually, springs are used to perform this task.
They force the valve to move to the fail-safe position when dangerous situations
emerge or damages occur. On failure of air supply, the Actuator springs act
against the pressure of the process medium on the plug to move the valve to the
fail-safe position and keep it there. From ICEweb Sponsor Samson
Controls.
ESD
Valve Fire Shelter - This is a neat idea, these
cabinets will provide the valve actuators with a minimum of 30 minutes of
protection against fire, so that the plant's emergency shut down systems
and services can quickly isolate and minimise damage, to protect
employees, assets and environment.
Pressure
Relief Valves and HIPPS systems - From ICEweb - These
systems have been utilised in Germany for over 20 years and are proven to be
extremely reliable in very rapid isolation of pipelines. However the technology
is still developing to a point where the required reliability meets all users
needs. They are so reliable that the need for other safety related devices such
as Safety Relief Valves can be minimised. They have the following advantages
- Negating the need for flare systems to be sized for the case of a well failing
to close.
- Production piping downrating, giving potential cost benefits of more than 25%.
- Fast inventory isolation within two seconds.
- Huge capital cost savings.
Valve Actuators - This is ICEweb's Technical Information on Control and Quarter Turn Valve Actuators.
Looking for Safety Instrumented
Systems Technical Information? See ICEweb's SIS
page.
Wish to learn more about Safety Instrumented Systems? Our valued sponsors Abhisam Software and Triconex run excellent courses.