An article in the October 2013 issue of Pumps & Systems discussed how to minimize leaks by applying proper design and material-selection standards. This article details new codes that have been established because the International Organization for Standardization (ISO) is currently updating certain standards, including ISO 15848 Parts 1 and 2.
American Petroleum Institute (API) 624 was updated in February 2014. A summary of the standards and their test methods are shown in Table 1.
The standards are strong. However, the community has hesitated to apply them across all businesses. While the change in the Environmental Protection Agency’s (EPA) policy is in review, business is moving forward in the rest of the world, except North America, which is actively pushing toward green and clean air pacts.
Valve emissions have been reduced in North America. However, they have increased or have been minimally changed in the rest of the world.
Current EPA guidelines have helped reduce valve emissions by handling issues such as:
- Leaks greater than 10,000 parts per million (ppm) are being eliminated.
- Leakage to 500 ppm maximum is being limited.
- New API 624 (released February 2014) has moved toward allowable leakages of 100 ppm or lower.
- Awareness of environmental initiatives in North America has grown tremendously, and such initiatives have given visibility to projects such as the Keystone XL Pipeline.
- Hydraulic fracturing is being examined more closely and codes and regulations in this space have been updated.
- Policy makers are becoming strict and inspectors are imposing fines when necessary.
End users are working closely with the standards organizations to develop mandatory requirements on API 622 and API 624, such as the following:
- Maximum stem to seal tolerance allowance (finishing)
- Criteria on leakage rates
- Maximum temperatures
- Minimum temperatures
- Leakage class
In fugitive emission testing, braided packing has been successful, which is cost effective for retrofitting existing and stock valves. Braided packing can be installed during shutdown or replaced during a valve refurbishment program.
These packings have been in use since the 1990s. The testing of fugitive emissions on braided packings is achievable on higher temperatures and longer test duration compared to standard packing materials (resulting in loss of binders at temperatures higher than 200 C).
The use of braided packings for new valves is not commercially viable or practical compared to traditional die-formed graphite lantern rings. The alternative packings (specially engineered) for new valves are limited to API 602 forged steel valves (valves less than 2 inches).
With regulation requirements, users must now determine the costs and the best way to be compliant. It requires additional cost to provide an engineered solution (such as special braided packing) in combination with managing production requirements because the cost impact is about 25 percent on special braided packing valves.
The majority of users have accepted these costs because of:
- The total cost of the valve
- Maintenance, shutdown and reliability costs
- The manpower required
- Meeting corporate safety and regulations
- Their industry image to be green and a clean producer
Because the requirements may be interpreted differently depending on the end users’ locations, the industry is still in partial acceptance of fugitive emission requirements and the use of braided packings for controlling these emissions.
The debate continues about the development of fugitive emissions regulations from the EPA, API, ISO, International Society of Automation (ISA), National Association of Corrosion Engineers (NACE), American Society of Mechanical Engineers (ASME) and many other organizations. End users are also requesting consistent research and improvement on current practices, including testing and approvals.
One way to ensure compliance is for the industry to conduct a survey of all valve manufacturers across the globe to validate that they have met the fugitive emissions requirements during the design phase with proper allowable code dimensions and the use of braided packing.