Emissions Valve Packing Technology Evolves to Reduce ...

1 118 SEALING SENSE. Emissions Valve Packing Technology Evolves to Reduce methane Leaks By Ron Frisard FSA Member M. ethane (CH4) is the limits for miles per gallon (mpg) was the lack of a unified testing second largest source of of automobiles from 1990 levels of standard. Twenty-five years ago, greenhouse gas emitted to 2,750 mpg. many refineries and Packing in the In 2013, CH4 accounted One of the main challenges manufacturers used their own for about 10 percent of all the industry needed to overcome testing standards with varying greenhouse gas Emissions from human activities. methane 's half- life in the atmosphere is much shorter than that of carbon dioxide (CO2); however, it is significantly more efficient at trapping radiation. Pound for pound, the comparative impact of CH4 on climate change is 25 times greater than that of CO2. during a 100-year period. One area responsible for contributing to the increase in CH4.

2 Is leaking equipment in the oil and gas sector. A major contributor to this leakage is valves that leak CH4. and sub-derivatives called volatile organic compounds (VOC) from the gland. During the last 30 years, governmental agencies have worked with industry leaders to address these leaks by increasing the implementation of new Technology . This focus has prompted Packing manufacturers to ramp up research and development of new materials. State and federal agencies have also tightened standards for maximum leak rate measurements of VOC values from 10,000 parts per million (ppm) 20 years ago to 100 ppm in most places in the today. As a comparison, that is like changing the Corporate Average Fuel Economy (CAFE) Image 1. Valve testing (Image and graphic courtesy of FSA). Oc t ober 2 0 1 5 | Pumps & S y st e m s 119. media (nitrogen, helium or methane 260 degrees C (500 F) with 1,510 to assume that all valves will at different concentrations), mechanical cycles.

3 Thermal cycles exhibit the same performance temperature ranges and thermal are completed once per day and with the same Packing . This is cycles. These variations made it are divided into 300 mechanical because all valves have their own difficult to compare the effectiveness cycles (150 at ambient and 150 unique design characteristics that of Valve emission Packing . A few at 260 C). A final 10 mechanical affect overall sealing, primarily standard organizations created tests cycles are completed at ambient tolerances and unique Valve for Valve Emissions addressing temperature, where the final design features. As a result, API. this issue. leakage measurement is taken. created a testing protocol API. The American Petroleum This test requires a large number 624 that focused on Emissions Institute (API) was one of mechanical and thermal cycles capability by Valve design and Valve organization that specifically and is designed to challenge manufacturer (see Image 1).

4 Focused on a detailed testing Packing manufacturers to improve One other significant standard procedure for Packing performance development. to note for Valve testing is in methane . The standard, API At the 2015 ISA Leak Detection International Organization for 622, has become a benchmark for and Repair (LDAR) Symposium, Standardization (ISO) 15848. Packing performance in the a paper by Buzz Harris from Sage Originally specifying helium for a variety of reasons, including Environmental focused on emission as a test gas and mass flow rate the Environmental Protection factors of leakage in refineries. His as a measuring protocol, the Agency's (EPA) insistence that main focus was comparing testing standard was modified earlier Packing performance testing be data from API 622 to current this year to include testing with conducted using methane instead common limits. He concluded methane gas using a concentration of other gases.

5 This standard that, in refining gas and vapor measuring method. became the catalyst for research service, the emission factor would API standards often complement and development efforts to create be reduced from x 10 -2 to x each other and build on previous Valve Packing that could meet a less 10 -5 kg/hour/source a decrease of work. In the case of API 624, one than 100 ppm requirement. more than a 1,000 times. of the prerequisites is that the Using methane as a test gas, API One important point is that Packing used has already been 622 requires five thermal cycles API 622 is not a Valve test but a tested to the API 622 standard. from ambient temperature to Packing test. It would be a mistake This is one reason the API 624. has fewer thermal cycles and Figure 1. Valve design considerations stem actuations than API 622. (the 624 test procedure requires 310 mechanical cycles and three thermal cycles to 260 C [500 F]).

6 API has also published design standards for other types of valves (API 600 and 602, for example). These standards are living documents that, as they are reviewed, will also reference the API 622 and API 624 standards for low-emission valves . This is significant in helping the petroleum industry Reduce overall methane Emissions . Some of the lessons learned from API 624 have focused on the machining tolerances of components. methane molecules are relatively small and leak rapidly p u m p s a n d s y s te ms . co m | O cto b er 2015. 120 SEALING SENSE. through small gaps compared accuracy of the gland load on the manufacturers and the Valve with steam and other media. Packing . Lubrication is critical, and industry have completed has served This means that users should new bolts (as compared with used to Reduce methane Emissions . not use standard gland and Valve bolts) can drastically affect how New Packing materials and dimensioning for steam service in the Valve seals operate.

7 Depending formulations, new testing Emissions applications. The main on the condition of the bolts, a standards and Valve design areas of concern are stem and user may not be getting the correct improvements have allowed box size tolerance, the Packing gland load. This is because, in most the industry to lower their gland clearance to the stuffing cases, the applied gland load is only environmental footprint by box and stem, and the stem to the assessed by torque, a measurement minimizing Emissions . inside diameter of the bottom of not of tension but of force over the stuffing box clearance. All of the threads and nut. When using Next Month: Insulating Over these dimensions are critical to unlubricated used bolts compared Rubber Expansion Joints: A Good successful Emissions sealing (see with new bolts, the same torque or Bad Idea? Figure 1). will result in a much lower tension We invite your suggestions for article topics as Another often overlooked area of and an under-loaded gland.

8 One well as questions on sealing issues so we can concern that is critical for sealing way to mitigate this problem is to better respond to the needs of the industry. methane is the bolting on the Valve use a load indicator, such as disc Please direct your suggestions and questions to gland. One of the most important springs height, which measures issues that testing confirmed is specific tension on the connection. that the condition of the bolts can The work the petroleum industry, have a significant effect on the regulatory agencies, Packing NEW: Hydraulic Institute's Wastewater Treatment Plant Pumps Guidebook U N M AT C H A B L E E X P E R I E N C E. This new guide provides the I N F L OW C O N T RO L. guidance necessary to select TRANSACTIONS. pump types, pump materials, and auxiliary components so the wastewater pumping system Jordan, Knauff & Company is a knowledgeable and experienced provider of a comprehensive line of performs effectively, efficiently, investment banking services to the pump, Valve and and reliably in various plant PXVEXMSR MRHYWXVMIW *PS[ 'SRXVSP.]

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