January 2009
Sealing the deal on clean air
ISA93, the Sealing Technologies committee, is ramping back up after a nine-year lull to dedicate itself to issues surrounding the Clean Air Act and industries focused on reducing fugitive emissions. The committee originally started in 1993 with a focus on on-off industrial valves. Valves, especially valve stem seals, were a priority for significant improvement in emissions reductions. Early assessments categorized valve stem seals as a major contributor to fugitive emissions.
“Experience has shown this estimate was very accurate,” said Chairman Rich Davis of Universal Products Biz in Conroe, Tex. “Data collected over several years from various petrochemical companies and petroleum refiners revealed industrial valves accounted for 60% of emissions sources in typical process units. Testing of valves and stem seals became a high priority for sealing products manufacturers, the valve manufacturers, and the user community,” he said.
The rush to test led to quite a few testing protocols. Lacking a recognized industry testing standard, the manufacturers and users faced all the usual obstacles with one quite significant difference—the EPA Clean Air Act instilled financial penalties and the possibility for individual prosecution for noncompliance.
Since published in 1999, ANSI/ISA SP93.00.01 has served as a guidepost for the development of other industry standards, including ISO 15848-1 Industrial Valves – Measurement, Test and Qualification Procedures for Fugitive Emissions and the API-622, Type Testing of Process Valve Packing for Fugitive Emissions. The standard gained a large following inside the user community, but with exceptions.
“As chairman of the committee, I see an opportunity to revisit the original standard using lessons learned, updated technology, and incorporation of time-tested end-user experience,” Davis said.
Some of the new technology includes instrumentation used to measure leakage for methane, which “has become more precise during the years since we originally wrote the standard,” Davis said. “We have gained a great deal of knowledge about the influence of how the mechanical attributes of valves will influence the test results. We have also gained more understanding surrounding the number of thermal and mechanical cycles needed to develop meaningful data. Comments from some labs have indicated the formula presently provided in the standard, establishing a corollary between methane and helium leakage, is not defendable and needs to be removed.”
The basic strategy for the committee is to update the roster, recruit some new members, and then start re-working the current standard: 93.00.01-1999 Standard Method for the Evaluation of External Leakage of Manual and Automated On-Off Valves.
Classifying valves
The standard applies to the classification of valve design and provides the methods for the testing of valve stems and body seals. It is not intended for production testing and excludes control valves. The results of the test methods will classify valve designs to performance levels in test temperature, pressure rating, concentration and parts per million of leakage, number of mechanical cycles, number of thermal cycles, adjustments to seals, or number of adjustments.
The purpose of the standard is to establish a uniform process for assuring manual and automated on-off valves tests using uniform methods and will meet user needs in complying with volatile organic compounds fugitive emissions requirements. The test method is not intended to be pass-fail criteria.
Test methods in the standard will apply only to valves with these stem motion designs: rotating and rising, rotating and non-rising, and non-rotating and rising. The classification will apply only to the stem motion design of 1.2. The test results of a particular valve may see use to extend the classification to other valves following these guidelines:
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Valves with identical stems and body seals material, geometry, and loading characteristics, when the stems and body seals diameters are within ±25% of the tested diameters
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Valves otherwise identical, meeting the criteria of 1.4a, which are applied below the tested temperature, down to ambient temperature
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Valves otherwise identical, meeting the criteria of 1.4.a, which are of a lower pressure rating
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Valves intended for vacuum service are beyond the scope of this standard.
The revamped committee’s first meeting was in Houston at ISA EXPO 2008. The next meeting is planned for some time in February.
For more information, contact Chairman Richard Davis at richd1@earthlink.net.
Ellen Fussell Policastro (efussellpolicastro@isa.org) writes and edits Standards.
Sensors back in lineISA97 is about standardizing the in-line dimensions of flowmeters to promote interchangeability of same type and different types across different manufacturers products, said committee chair Brian Smith of Eneos Nova in Sarnia, Ontario, Canada. “The idea was conceived by Ian Verhappen as an enhancement of the Fieldbus interchangeability concept,” he said. “The benefit would be to reduce or eliminate the need for piping changes when a flowmeter replacement is required. Users could interchange flowmeters without limitations resulting from the current differences in flow meter in-line dimensions.” The scope of this revamped standard is to prepare a series of standards to specify the process connection dimensions of sensing devices and thus promote innovation in sensor technology and interchangeability of similar devices. “Our purpose is to create a series of standards on process connection dimensions for the various types of sensors, such as flowmeters, pressure sensors, and discrete devices,” he said. “All users in all industries could use flowmeters that meet this standard to change one brand for another,” Smith said. “They can also use them to change a vortex flowmeter with a magnetic flowmeter and any other suitable flowmeter having the same in-line (face-to-face dimensions).” Compatible end connections are also required such as DIN, ANSI, etc. The revised draft standards for flanged and wafer style vortex flowmeters have been balloted, and the committee is now working to resolve comments. “We will schedule our next meeting as required depending on the results of this effort,” Smith said. For more information, contact Brian Smith at brian.smith@ineos-nova.com. |
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