In addition to the health and safety risks, fugitive emissions also result in significant production and economic loses. Concerns over greenhouse gasses and climate change are leading to more restrictive governmental regulations on allowable emissions. Plant owners are being forced to spend more time and money to stay in compliance with the lower emission mandates. There have been several reports stating 50 to 60% of emissions from a plant are attributed to external leakage from valves. In an attempt to reduce emission from valves, numerous standards were developed, such as ISO-15848-1 and -2, TA-Luft, EPA Method 21, and several more to establish a test methods and guidelines for allowable emission levels. In addition, unsatisfied with the concessions made during development of these standards, big international companies have developed their own internal standards to be followed. So are we any closer to a solution to the problem of complying with the regulations?
Testing the standards
The fugitive emission standards vary significantly from each other, because they are based on the individual experience and perceived needs of different industrial sectors or players. As fulfilling these standards requires careful laboratory setup and time consuming testing, it represents very high cost to our industry, in both expense and time. Moreover, the standards are not comparable, as the test requirements, measurement methods and approval criteria differ from one standard to another – and even inside one standard there may be several different test setups that are disparate. There is also a debate on the indicator gas used: although methane is predominant type of greenhouse gas emitted as a fugitive emission in the oil and gas sector, helium is frequently the gas used in emission tests.
Compliance with the standards or with clean air regulations?
Nonetheless, the most serious issues with believing that compliance with the standards will result in compliance with clean air regulations is that the problem of fugitive emissions is not tackled in a proper way: a passed test does not guarantee the success in real service where process conditions, such as thermal stresses, vibrations, mechanical wear and corrosion will have a huge impact. Ultimately, emissions to the environment are controlled by the plant operators – manufacturers can only assist by providing designs that initially, are capable of remaining tight when subjected to the thermal, pressure, and mechanical forces and cycles a valve may experience in service. Therefore, the belief that certification of compliance to the current emission standards will ensure compliance with ever-tightening regulations is flawed. The basis of these standards should be revised and simplified to reflect the limited role the valve design has in emissions performance, and compliance with environmental regulations ensured more thoroughly than nowadays.