Alternate Monitoring Plan for DTM Valves

1. 10th LDAR SymposiumMay 19-20, 2010San Antonio, Texas Alternate Monitoring Plan for DTM Valves Making the AWP Work for at Least One Niche Area By Buzz Harris, Heather Hedgren, Ann Landry, and Joe Wilwerding

2. Overview • Background • Alternate Work Practice • DTM vs. NTM Populations • Leak Characteristics for DTM vs. NTM Valves • Mean Time Between Leaks for DTM vs. NTM Valves • Projected Emissions from DTM Valves on Annual vs. More Frequent Monitoring • Proposed Alternate Monitoring Plan for DTM Valves • Conclusions and Path Forward

3. Background • Valves are present in refineries and chemical plants in large numbers • Valves can be found at ground level and on OSHA-compliant platforms (normal-to-monitor, NTM) • Valves can also be found on the sides of towers/vessels and in pipe racks (difficult-to-monitor, DTM) • EPA defines DTM valves as those where the monitoring personnel must be elevated by 2 meters or more • Method 21 monitoring frequency differs: • NTM valves must be monitored quarterly • DTM valves must be monitored annually

4. DTM Valves • DTM valves can be generally accessed by: • Ladders • Man Lifts • Scaffolds • Crane Buckets • Monitoring time (labor cost) is higher for all these DTM access methods and there are additional out-of-pocket costs for man lifts, scaffolds, and crane buckets • There are safety implications increasing the risk of serious injury through falls when accessing DTM valves • Site safety programs are trending towards requiring scaffolds rather than allowing pipe rack work with a fall arrest system

5. Alternate Work Practice (AWP) • The AWP, which uses optical imaging to detect leaks, was highly anticipated as a means to reduce the high labor cost of Method 21 monitoring • Since optical imaging allows leak detection without close approach to a component, it held great possibilities as a way to monitor DTM components, however: • A requirement was inserted between proposal and final rule to require an annual Method 21 for all regulated components • For DTM valves, the AWP offered no relief from the current regulations, but instead required the addition of 5 optical surveys per year to the annual Method 21 monitoring that is already required

6. Relative Populations • Most valves are installed so that they will be NTM • Some NSPS and HON-style rules require that newly designed units have less than 3% of total valves as DTM • Sage has been keeping benchmarking information on DTM valves for 118 facilities:

7. Relative Leak Frequencies • There has been an argument within the LDAR community almost since there has been an LDAR community: • Do DTM valves leak less frequently because they are operated less frequently? • OR... • Do DTM valve leak more frequently because they receive less frequent leak inspections and preventive maintenance? • The monitoring data to answer this question have long been available, but it is more fun to argue based on conjecture than to run database reports to support your argument, and even if you did it would only be for your particular facility.

8. Detailed Look at Six Facilities • All are petroleum refineries • Total valves average about 29,500 • Range of total valves was from about 11,000 to 46,000 valves • DTM valves averaged 3.72% • DTM valves ranged from 1.28% to 14.15% • All these facilities were under Consent Decree mandating a 500 ppm leak definition for valves • Sage had access to complete monitoring data for up to 5 years for these facilities, from which we were able to examine leaks at various concentration levels • One refinery performed quarterly monitoring on most of the valves designated DTM

9. Relative Leak Frequency Data

10. Leak Rate Observations • The percent leaking for DTM valves is fairly close to the percent leaking for normal access valves • Overall average % leaking at 500 ppm is 1.63% for DTM vs. 1.96% for normal access • Overall average % leaking at 10,000 ppm is 0.36% for DTM vs. 0.30% for normal access • There appear to be slightly more frequent leaks above 10,000 ppm for DTM than for NTM valves • The facility that performs quarterly monitoring on most DTM valves showed lower leak percentage for DTM than NTM valves • This could be evidence that the longer time for leaks to propagate between monitoring events with annual monitoring allows more leaks to reach 10,000 ppm

11. Mean Time Between Leaks (MTBL)

12. MTBL Observations • There is little difference between MTBL for DTM and NTM valves • The average MTBL for DTM is 3.32 quarters vs. 3.18 quarters for NTM • Four of the six facilities actually show a lower MTBL for DTM valves (likely because of leaks found on two monthly follow-up monitoring events under NSPS) • All these figures are based only on valves that leaked twice during the span of data available, so the overall MTBL would be lower if there were data for the valves that had zero or one leak in the time span of this data • This suggests that we can use NTM valve leak frequencies, which are much more robust with greater numbers of observations, as a predictor for DTM valve leak frequencies

13. DTM Leak Emission Estimates by Size Based on 10K Pegged Emission Factor, Petroleum Industry Valves, 0.064 kg/hr/source Based on <10K Screening Range EF, Petroleum Industry Valves, blend of LL and GV

14. Emission Rate Observations • The large (>10,000 ppm) leaks from DTM valves account for 93.5% of the total DTM valve emissions • Finding those large DTM valve leaks earlier could reduce overall emissions from DTM valves • Demonstration studies showed success in optically imaging 10,000 ppm plus leaks at a distance with the 50 mm lens on the FLIR GasFindIR • Six refinery data show an average MTBL for DTM valves that leak multiple times of 3.32 quarters or about 10 months • An Alternate Monitoring Plan that emulates the AWP 60 day monitoring frequency would likely cut the time before detection of big leaks by as much as 8 months per DTM valve leak found • This could reduce the emissions for DTM valve large leakers to by as much as 80%

15. Alternate Monitoring Plan Proposal • Include AWP sections by reference that specify requirements for daily instrument check, surveys, and recordkeeping • It may be difficult to get approval of an AMP based only on optical imaging, because the smaller portion of emissions that come from 500 to 9999 ppm leaks might increase and be more significant over time • An Alternative Monitoring Plan based on optical imaging every 60 days plus Method 21 once every three to five years should control the growth of lower leak rates and reduce emissions by finding larger leaks earlier, while reducing monitoring cost and reducing fall potential during DTM valve monitoring

16. AMP Load-Leveling Schedule Need to adjust for facilities with less than 18 units or uneven multiples of 18

17. Conclusions • A review of DTM vs. NTM valve leak characteristics at six refineries indicates that leak frequencies and mean time between leaks are more similar than different • The emissions from large DTM valve leaks (>10,000 ppm) account for about 93.5% of total DTM valve emissions • More frequent monitoring to discover the large leakers earlier should reduce total DTM emissions • Less frequent Method 21 monitoring could reduce cost and safety risks

18. Path Forward • Sage has done the entry level work to show that an Alternate Monitoring Plan for DTM valves could be a win-win situation • The regulated community will need to provide financial backing if we are to refine these rough estimates to the level needed to convince EPA to approve an AMP • Optical imaging is a technology with great promise, but with little or no LDAR application several years after promulgation of the AWP • DTM valves are nearly the perfect application for optical imaging: reducing emissions, cutting costs, and improving safety • Help us make something useful of the AWP!