09 Nov API 622: Valve Packing Standards for Fugitive Emissions
We rely on valves to stop and seal the flow of media in its various forms: solids, liquids, and gases. Leakage of solids or liquids is relatively easy to spot, but some gas leakage isn’t something that can be detected by the naked eye.
With the help of testing, we are made aware of the failure of a valve to sufficiently stop gases from escaping. With this knowledge, we can improve our processes by upgrading problem valves.
The Importance of Test Standards Organizations
Quality standards for valve and packing tests are set by industry organizations such as ANSI, API, ISO, MESC, and TA-LUFT.
Today, we’ll focus on API pressure testing standards. The American Petroleum Institute (API) was founded in 1919 after World War I. The war raised awareness of the vital role the petroleum industry holds in the United States, so the API was formed to bolster and secure domestic oil and gas production. Over 700 API standards have been put in place to promote efficiency, sustainability, and safety for both operations and the environment.
3 Types of API Valve Testing
- API 622 – Tests process valve packing for levels of fugitive emissions.
- API 624 – Tests rising stem valves equipped with graphite packing for any fugitive emissions.
- API 641 – Tests quarter-turn valves for levels of fugitive emissions.
Because API 622 is the first in the series of embedded low E valve and packing standards, it’s what we’ll cover today. For valves tested at API 641, packing must first qualify for the API 622 test. Also, for the packing used in an API 624 test, the valve must have been tested with API 622 first.
Why Are Fugitive Emission Tests Necessary?
Depending on what is leaked, fugitive emissions can be costly. There is concern surrounding methane gas emissions because this gas is flammable, considered to be harmful to the environment, and is a commodity. Not only is fugitive methane emission an environmental concern, but it’s also a financial loss when seeping valuable methane or incurring costly governmental fines.
With valves being to blame for over 50% of fugitive emissions, they are the main focus for testing. The Natural Resources Defense Council estimates that leak monitoring and repair could potentially account for 18% of methane emission reduction. When plant operations call for fugitive emissions monitoring, LDAR (leak detection and repair) is typically part of a monthly testing protocol.
The good news is that as natural gas production has increased, emissions from this production continue to decrease. These improvements are due to voluntary action, compliance with regulations, or both. Advancements in technology along with improved testing are how we continue to mitigate fugitive emissions.
API 622 Performance Test
API 622 has three iterations. The first was established in 2006, the second in 2011, and the latest in 2018.
This most recent edition further restricts emissions leakage by lowering the number to 100 parts per million volumetric (ppmv) and it also does away with the allowance of a gland bolt adjustment. In addition to the 1/4-inch packing (as part of the earlier test versions), the third edition involves a 1/8-inch packing sample test. This rectifies a problem with the previous tests iterations.
API 622 is fundamentally a performance test. The following explains the weaknesses the valves tests are checking for.
For the purpose of leak detection, the fugitive emission test for API 622 is not a pass/fail test. It’s a 6-day stress test to see how many thermal cycles the valve can take before emissions exceed a certain threshold (previously 500 ppm and now 100 ppm).
Testing is a 6-day process that amounts to 1500 cycles. Because methane gas is used for this testing, it is best that this procedure happens outdoors. Each day, the valve is tested at 150 cycles in ambient temperature, then for another 150 cycles at 500°F. Components cool overnight for another day of testing. If by day five the valve holds up, it has its final trial on day six with ambient temperature cycles increased by 10.
For this test to prove successful, the leakage cannot exceed 100 ppm and unlike prior versions of this test, the gland cannot be readjusted to correct for leakage.
Like the fugitive emissions test, this is also not a pass/fail assessment. It monitors for pitting in the metal to observe how well the packing sticks to the stem. It also evaluates the overall quality of the packing.
This metal testing involves soaking and compressing the packing 30,000 megapascals. This packing is then wrapped around the metal. Different valve stems can be tested according to the different metals involved.
Different from the fugitive emission and corrosive testing, material health testing is pass/fail. It examines the material properties of the packing including lubrication content, polytetrafluoroethylene content, chemical leaching, plus weight and density.
For this component of testing, valve standards are not met if:
- The graphite foil loses an excess of 15% of its weight at a temperature of 1000°F
- Graded packing loses more than 50% of its weight.
Gaining the API certification seal is a complex and thorough process, but it gives us in the industry the peace of mind that the valves we use are effective for minimizing fugitive emissions.
Contact Butterfly Valves & Controls Today
The truth is that faulty valves do carry the potential to affect your bottom line, especially when your processes include the containment of materials that are considered to be environmental pollutants.
While valves are designed to stop media from passing through channels, they ended up being the culprit for over half of fugitive emissions. Rigorous testing and technology advancement is how we address and improve upon this known issue.
Butterfly Valves & Controls takes the guesswork out of choosing the most efficient and environmentally responsible valves. Contact us with any questions you have about what valve certifications you may need for your industry. When you need an upgrade for your valves, reach out to us for a free quote.