Continuous Valve Monitoring for Product Loss Prevention, Emission Reduction and
ROI
Background
Pressure relief valves have been identified as a significant source of emissions and product loss in petroleum
refineries. Isolation valves and vent valves also contribute to unplanned and undesirable product loss and
pollution. A number of states with non-attainment challenges for airborne pollutants have implemented programs
requiring strict monitoring of valves venting directly to atmosphere. Virtually all states have controls for
monitoring major sources of emissions including smoke stacks and flare systems. Current practice involves
capital intensive flare gas recovery systems to use product lost through accumulated leakage as fuel or return to
processing when appropriate. While this mitigates emissions and waste to some degree, prevention of loss is a
much more effective solution.
There is highly attractive ROI achievable with continuous monitoring systems that prevent loss and reduce
emissions with the associated penalties. The benefits of reducing unplanned discharge due to leakage is typically
are millions of dollars per year in product savings alone. These savings can be realized using wireless sensor
systems with total investment paybacks measured in months or weeks versus years. As emission reduction
emphasis increases due to current climate change policy, the ROI will become even more compelling.
One of the challenges that companies have faced in implementation of continuous monitoring systems is the lack
of infrastructure for sensing and data collection. The devices to be monitored are widely dispersed throughout
plants with large areas, have no existing power or signal transmitting wire infrastructure, so the capital costs
associated with the power and communication services have historically prohibited continuous monitoring.
Continuous Emission Monitory Systems (CEMS) have been mandated for major sources of emissions including
flares, but identifying sources of base load flows remains restricted by infrastructure and manpower.
EPA Investigation Alert
An Environmental Protection Agency National Enforcement Investigations Center Alert published in October of
1999 reported that plant audits revealed the number of leaking valves was up to 10 times greater than reported by
certain refineries. The EPA estimated that leaks not found and repaired could be resulting in additional VOC
emissions of 80 million pounds annually at just a few plants.
Valves are usually the single largest source of fugitive emissions. The emissions from any single piece of
equipment are usually small, however a few valves can be responsible for a very high percentage of the total
leakage at any plant. Because of the large number of devices, cumulative emissions can be substantial. Fugitive
emissions accounted for 22% of all emissions from non-refineries, but account for more than 55% of all refinery
emissions. Fugitive emissions can be reduced by up to 90 percent if leaks are detected and repaired in a timely
manner.
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Valve Monitoring Regulations
At least 2 high profile jurisdictions have implemented mandatory monitoring of individual sources of emissions,
including pressure relief and other valves that discharge directly to atmosphere.
California Rule 1173 (Amended February 6, 2009) 1173 - 10
(h) Atmospheric Process PRD (Pressure Relief Device) Requirements
(1) The operator … shall continuously monitor atmospheric PRDs located on process equipment
by installing tamper-proof electronic valve monitoring devices capable of recording the
duration of each release and quantifying the amount of the compounds released …
Texas Commission on Environmental Quality
Chapter 115 - Control of Air Pollution from Volatile Organic Compounds
Each vent gas stream … must be tested …to establish maximum potential highly-reactive volatile organic
compound (HRVOC) hourly emission data … to demonstrate compliance with the control requirement of
… this title (relating to Site-wide Cap and Control Requirements).
(b) Alternatives to the testing requirements of subsection (a) of this section, for vent gas streams that are
not controlled by a flare, include the following.
(1) The vent gas stream may be equipped with a continuous emissions monitoring system
(CEMS)
(e) Any pressure relief device which has vented to the atmosphere shall be monitored (with a hydrocarbon
gas analyzer) and inspected within 24 hours after actuation and the results reported in accordance with
§115.786 of this title.
An as alternate to periodic testing, TEQ allows installation of continuous monitoring instrumentation.
Benefits of Continuous Monitoring
Many of the companies impacted by the above regulations used wireless sensor systems to comply with the valve
monitoring aspects of the rules.
Recently, a number of companies have initiated energy conservation and emission reduction projects to conserve
cash and limit preventable capital investments associated with mandated compliance such as piping atmospheric
vents to flare gas recovery systems.
Some examples of dramatic cost benefits include:
European refinery – selected 19 valves for continuous monitoring and detected major leak source
resulting in cost saving of $1.1 million product value for investment of $38,000.
Refinery in Northwest USA – implemented system for continuous monitoring of 50 PRV for product loss
reduction in 2004. Based on results, system was scaled up to 100 units 2006-2007.
Gulf Coast Chemical Plant – evaluated 50 permanent and 100 temporary devices for in-situ monitoring.
Payback expected in 6 weeks with accumulating benefits thereafter.
West Coast Refinery – installed 250 PRV monitors with plan to expand to 400 points.
Ethylene terminal and pipeline – expects to save $1 million per year in lost product for investment of less
than $50,000.
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Adaptive Wireless Solutions
577 Main Street, Hudson MA 01749
Ph: (978) 875 6000 Fax: (978) 562-2563
www.AdaptiveWirelessSolutions.com
West coast Refinery spent over $1,000,000 for hard wired solution to comply with regulation while
wireless sensing solution cost was less than $50,000
Current Best Practice
Pressure relief valves are inspected and tested on a periodic basis as part of plant safety policy. Today’s best
practice is typically based on a time interval inspection program, with the interval being determined by inspection
history of a particular valve. On a macro basis, between 30 and 40% of pressure relief valves do not pass the
recommended seat leakage criteria during routine testing. Because the tests are conducted in controlled shop
environments, inspectional intervals are extended as long as possible and can be up to 5 years. The duration of
leaking condition is not known but ranges from weeks to years, depending on inspection interval and operating
conditions.
When valves are known to be leaking or have been lifted due to a pressure excursion, they are normally tested and
repaired at the first practical opportunity. Maximum time delay for repair of leaking valves from time of
detection is proscribed in EPA regulations. Post excursion tests result in considerable lower percentage of leak
detection that is discovered at routine tests (usually about 10%), indicating that this element of best practice is not
effective at identifying sources of leakage to flare or atmosphere.
Although it is verified that many valves leak a small amount, a few valves leak profusely and are significant
sources of lost product and emissions. Early detection of these sources can lead to appreciable reduction in cost
and pollution. Continuous monitoring using wireless sensors effectively identifies leaking valves, including
inaccessible units, with immediate response. When flare system base load increases, it is often due to sources of
this type that are difficult to pinpoint.
New Best Practice
Each plant has initiatives to improve safety, reliability and efficiency. Valve inspection and repair records plus
mass balance measured product loss can provide quantifiable details to establish a clear understanding of the
opportunity for gains to be earned through continuous monitoring. Creating new best practices using available
wireless sensor technology results in rapid ROI and produces ongoing benefits. Portable wireless sensor systems
are easy to deploy, do not require power or signal wire infrastructure and enable responsible personnel to focus
their inspection and repair efforts on identified actions that have immediate results.
Rather than remove valves for inspection after pressure excursions, it is possible to conduct in-situ leak tests that
do not impact operations and 90% of the time will result in validation that the valve can remain in service.
Immediate indication of leak initiation will direct maintenance personnel to valves that require attention and will
result in measurable loss prevention. In the short term, the number of valves removed for repair that fail leak
criteria will increase while valves removed for routine operational testing will pass, validating improved
effectiveness of the new best practice. EPA inspection data verifies that 90% of valve leakage can be eliminated
if valve leaks are detected and repaired in a timely manner. It is possible to extend the periodic inspection interval
based on new data collected by the wireless sensor network.
In its report titled “Industrial Wireless Technology for the 21st Century”, the US Department of Energy quotes the
President’s advisors on science and technology assertion that development of wireless sensor technology could
improve industrial production efficiency by 10% and reduce emissions by more than 25%. These are compelling
gains that can be achieved by adopting available technology as part of new best practices including continuous
valve monitoring.
3
Adaptive Wireless Solutions
577 Main Street, Hudson MA 01749
Ph: (978) 875 6000 Fax: (978) 562-2563
www.AdaptiveWirelessSolutions.com