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2016 VMA Technical SeminarFugitive emission testing and certification
of valves – What we will have to do next?
David Bayreuther
March 10, 2016
OutlineSources of emissions
History of legislation
Review of standards
Inconsistency in standards
What is next?
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• Primary types of sources:
- equipment leaks
- process venting
- evaporation losses
- flaring
- accidents and equipment failures
• Methane (CH4)
- predominant greenhouse gas emitted
by the oil and gas sector
- more than 20x the global warming
potential of carbon dioxide
- detrimental to public health
Sources of fugitive emissionsRefineries and chemical plants
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EPA reports 11% decrease since 1990...but will increase by 2030 if no action taken
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History of legislationFugitive emissions
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• Air pollution control act 1955
• Clean air act 1963
• CAA amended in 1970
• CAA amended in 1990 to include
LDAR
• Late 1990s, under-reporting facilities
assign dedicated management
• Late 2000s, consent decrees revised
to require low leak packing technology
• Focus is on plants to monitor and
repair
• Plants look to SDOs for help
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• ANSI / ISA S93.00.01
• ANSI / FCI 91-1
• TA-Luft VDI 2440
• ISO-15848-1 and -2
• Shell SPE 77/300
• Shell SPE 77/312
• ChevronTexaco
• API-622
• API-624
• API-641 (pending)
Numerous emission test standards are writtenFugitive emission test standards
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And more to follow…isn’t this too much already….why?
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• Different tests for various valve types
• Emphasis on accuracy of the test
• What is an appropriate test method
- Measurement method(s)
- Helium vs. Methane
- Units of measure
- Test temperature
- Temperature range
- Number of thermal cycles
- Test pressure
- Packing adjustment allowed?
- Static vs. dynamic leakage
• Lets review some of these issues in
more detail
Confusion in the standards committeesHow do we prove performance through testing?
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• Global methods
- Vacuum
- Flushing
- Bagging
Which measurement method?Global versus local method
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• Local method
- Sniffing
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• Methane
- Limited laboratories
- Non-toxic but extremely flamable
- Explosive when mixed with air
- AIT limits maximum test
temperature
• Helium
- All laboratories
- Readily available
- Not flamable
- No limit to maximum test
temperature
Testing with Helium or Methane?Safety and other considerations
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• Methane
- Units are ppmv
• Helium
- Volumetric flow units are mbar-l/s per
mm of stem diameter
- Ranges from 1,78x10-7 to 1,78x10-4
or
- Mass flow units are mg/s per meter of
stem diameter
- Ranges from 10-5 to 10-2
Units of measureCan you correlate to actual in-service results?
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Not possible to correlate Helium to Methane…. or mbar-l/s-mm to ppmv
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• Goal is to verify that the seal
design will remain tight through
entire valve temperature rating
• Typically, the internal fluid
establishes the operating temp.,
and the packing and seals are
closer to ambient
• Using local heat sources the
packing box does not reach the
full test temp.
• Test in an oven and the entire
valve achieves the test temp.
• ISO-15848-1 versus API
Test temperatureIs it acceptable if the packing does not reach the test temperature?
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• ISO-15848-1
• Can require 2 tests to cover the
temperature range
• Test at room temp qualifies valve
from -29C to +40C
• Problem example with ISO-15848
Test temperature rangeWhat is ambient temperature?
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• Thermal cycles establish time
needed to complete test
• Reason for a thermal cycle
• Min. per ISO-15848 is 2 cycles
• Some standards require up to 5
• Examples of test results
Number of thermal cyclesHow many are necessary?
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• Valve rating at the test
temperature?
• API standards use 600 psig or the
valve body rating, whichever is
less
• Challenges in achieving full valve
rating
Test pressureWhat is the appropriate value?
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• Yes - it simulates the real
operating environment
• Yes – but only once after the 1st
thermal cycle
• No - it indicates a problem with the
valve design
• ISO allows one adjustment per
stage of testing
• API allows none
Is packing adjustment during test allowed?The opinions vary
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• One successful test in a laboratory
is no guarantee of future results
• Success in a laboratory does not
equal success in the plants
• Factors not address in laboratory
test:
- thermal stress
- pipe stress
- flow erosion
- vibration
- effects of corrosion (both within the
system and from outside conditions)
- mechanical wear
- aging
- environment
Despite all the work, test results are not definitiveOther factors to consider
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• Comparison between different
standards is nearly impossible
• Standards do not take into account
the process conditions
• The number of tests within the
standards is practically unlimited
- For a valve manufacturer it is
impossible to have all the
combinations covered
Summary on testingEmissions testing standards are a confusing mess....
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But we have excellent results
Significant improvements to packing and seal materials, and
installation techniques, leading to lower fugitive emissions
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What does the future bring?
• Latest legislation changes
- Announced strategy to reduce
Methane emission in 2014
- In 2015, announced new goal to cut
Methane emissions from oil & gas
sector by 40 – 45% by 2025
• EPA is seeking expert input on
how to update and modernize the
LDAR program
• API developing a new standard for
rotary valves
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More change....