p.1 

OAR Box 1168 

Prepped by Ollie Stewart 

Document Number: 

104) ll-C-33 

Docket Number: 

A-89-10 

Printed 4/29/2008 11:23:20 AM Sheet 104 of 131 
7 P.2 

% 

u a 

D STATES ENVIRONMENTAL PROTECT 

Office of Air Quality Planning and Stan 

Research Triangle Park/North Carolina 

A-89-10 II-C-33 

Dear Reg Neg Committee: 

As promised in Phil's note of 10/31, enclosed for your review and 

comment is a revised draft of the preamble section on the use of the data. 

This section is being circulated for early review to ensure it reflects the 

Committee's thinking and because of interest expressed by several members. 

This draft has been revised to reflect, with one exception, the comments we 

received from Committee members. The exception deals with the comment that we 

need to verify the "accuracy" of the data in Table 1. Due to time demands of 

other issues, it has not been possible to check Table 1. Again in this draft, 

we have focused primarily on the principle basis for the provisions and have 

not attempted to ensure that all numbers are correct and consistent. These 

details will be addressed shortly. 

Work is continuing on the preamble and if you have any questions on 

progress feel free to call me or Rick. 

Sincerely, 

Jan Meyer 

Y > * 
P.3 

The Data and Information Considered 

Background and Summary of Information 

In the late 1970's and early 1980's, EPA conducted several studies to 

evaluate and quantify emissions from equipment leaks in refinery operations 

and in chemical plants. In these studies, EPA collected data and evaluated 

leak frequency, mass emissions, and methods and effectiveness of leak 

prevention. These studies showed that equipment leaks were a significant 

source of emissions and that the majority of emissions were associated with 

equipment leaks measured at concentrations greater than 10,000 ppm. These 

studies also demonstrated that a program consisting of inspection of equipment 

and maintenance of the leaking equipment was an effective means of reducing 

emissions. The control measures identified at that time were estimated to 

achieve overall a 60 to 70 percent reduction in emissions from equipment 

leaks. The data and conclusions from these studies served as a basis for 

EPA's equipment leak regulations and guidelines that were issued in the early 

1980's. 

Information obtained in these studies also showed that leak frequencies 

varied widely among process units and source types and that factors that 

affect leak frequencies were not well understood. Specifically, studies such 

as EPA's study of 24 chemical process units (24-Unit Study) showed that the 

frequency of leaks greater than 10,000 ppm ranged from 0 to approximately 30 

percent among 15 different chemical processes. Similar chemical processes also 

showed large differences in leak frequencies; for example, the leak 

frequencies for gas valves varied from 0 to 18 percent for 3 ethylene 

dichloride units. In subsequent studies, EPA evaluated leak frequency as a 

1 
P.4 

function of process parameters and equipment design and identified no single 

factor that determined leak frequency. Leak frequencies are believed to be a 

function of component design, construction, material, and age, component 

design specifications, quality and frequency of maintenance, operating and 

training practices used by the company, diligence, and other unidentified 

factors. The current EPA rules and guidelines do not require sources to 

achieve particular performance levels or to install low emission design 

equipment. As such, the residual emissions will vary among process units and 

best controlled units will emit less than typically controlled units. 

In the last three years, EPA has received information that shows 

significantly lower leak frequencies at 10,000 ppm for some chemical processes 

than was representative for the industry as a whole in the early 1980's. This 

information was one consideration in EPA's decision to develop a new 

regulatory approach for equipment leaks through the regulatory negotiation 

process. The information is briefly summarized in the paragraphs below. In 

addition, where sufficient information is available, these data are included 

in Table 1 which compares leak frequency by component type with the previously 

calculated SOCMI average leak frequency. In general, these data were 

collected following the procedures specified in Reference Method 21, and the 

results represent a single monitoring survey conducted over a discrete time 

period. 

Units subject to the Benzene Equipment Leak NESHAP. During EPA's 

reconsideration of the benzene equipment leak NESHAP (54 FR 38044), EPA 

examined compliance reports from 1987 and 1988 for a randomly selected sample 

of 25 facilities subject to the standard, which requires a 10,000 ppm leak 

detection and repair program. This review showed that many facilities had no 
P.5 

valves or pumps exceeding 10,000 ppm and no facilities had more than 1.5 

percent valves or more than 12.5 percent pumps exceeding 10,000 ppm. The 

average frequencies of sources exceeding 10,000 ppm were 0.27 percent for 

valves and 2.3 percent for pumps. These frequencies, in general, are lower 

than the average frequencies of 3 to 5 percent for valves and approximately 10 

percent for pumps exceeding 10,000 ppm which had been expected under the 

standard. 

Acrolein process units. In 1989 EPA received screening data and process 

information on two acrolein process units. These data were collected 

voluntarily by the company to provide better emission estimates than could be 

obtained using the SOCMI average factors. The monitoring data represented 

eight types of equipment (gas valves, light liquid valves, light liquid pumps, 

flanges and other connectors, pressure relief valves, sample points, openended lines and compressors). These monitoring data were collected following 

the procedures specified in "Protocols for Generating Unit-Specific Emission 

Estimates for Equipment Leaks of VOC and VHAP", (Protocols) EPA-450/3-88-010. 

In general, particular care was taken in measurements of equipment with near 

zero or less than 200 ppm emissions. In addition, one of the units had 

approximately 60 percent sealed bellows valves and the other unit had no 

sealed bellows valves. 

The screening data indicated average leak frequencies of 0.26 to 0.09 

percent for valves and of 0.13 to 0 percent for flanges and other connectors 

at leak definitions of 100, 1,000, and 10,000 ppm. These data also 

demonstrated that both conventional and sealed bellow valve designs achieve 

very good performance. Pump leak frequencies were less than 4 percent at 100, 

1000, and 10,000 ppm. Of all the components screened, more than 98 percent had 
P.6 

screening values below 10 ppm. These leak frequencies are substantially below 

the levels found by EPA in studies conducted in the early 1980's. 

Amine Unit W.VA. In 1987, EPA received monitoring data for two process 

units handling amines. These units were selected for testing because of the 

relatively severe service conditions (i.e., temperature and pressure) and high 

vapor pressures of the process materials. One unit (unit 1) was characterized 

as handling relatively nontoxic and innocuous substances and the other unit 

(unit 2) was characterized as handling a more toxic compound, one with a 

threshold limit value (TLV) of 10 ppm, which was capable of causing a public 

nuisance. These data were collected voluntarily by the company to calculate a 

unit specific emission estimate using EPA's leak/no leak emission factors. 

Monitoring data were provided for pumps, valves, and flanges and other 

connectors. 

The monitoring data for unit 1 showed 33 percent of the pumps, 16 

percent of the light liquid valves, 27 percent of the gas valves, and 0.4 

percent of the flanges and other connectors exceeding 10,000 ppm. Unit 2 had 

5.6 percent of the pumps, 0.8 percent of the light liquid valves, 1 percent of 

the gas valves, and 0.1 percent of the flanges and other connectors exceeding 

10,000 ppm. The data for unit 2 indicate that technology is available to 

reduce leaks and suggest that health and safety considerations are important 

factors affecting use of better technologies and maintenance practices. 

Ethvlbenzene/Stvrene (EB/S) Unit Tx. Limited information was received 

on screening values measured at this facility's ethylbenzene/styrene process 

unit, which is subject to the benzene equipment leak NESHAP. Screening data 

were provided for a total of approximately 2500 valves and pumps. The data 

were provided as time aggregated summaries of screening valves for a one year 
P.7 

period from 1987 to 1988. These data indicated that 99 percent of the time 

the valves and 90 percent of the time the pumps had screening values less than 

500 ppm. Information submitted for compliance with the benzene equipment leak 

NESHAP showed on an annual average basis 0.04 percent of the valves and 3.6 

percent of the pumps exceeded 10,000 ppm. No description was provided of the 

procedures used in the data collection, other than Reference Method 21 was 

used. 

Chemical Manufacturers Association Studies of Butadiene (BD). Ethylene 

Oxide (EO). and Phosgene Process Units. In addition to the preceding 

information, comprehensive screening data were also provided to EPA on 33 

butadiene (BD), ethylene oxide (E0), and phosgene production process units. 

The monitoring data represented eight types of equipment (gas valves, light 

liquid valves, light liquid pumps, flanges and other connectors, pressure 

relief valves, sample points, open-ended lines and compressors) at essentially 

all BD, EO, and phosgene producers operating in the United States. These data 

were collected voluntarily by the CMA committees to provide EPA with better 

industry-wide estimates of emissions from equipment leaks at these process 

units than could be obtained using EPA average factors for SOCMI. These 

monitoring data were collected following the procedures specified in the 

Protocol. These studies provide the most comprehensive equipment screening 

data available that document the full range of leak frequencies for large 

numbers of process units used for the production of specific chemicals. 

Conditions in the equipment surveyed spanned a wide range of temperatures and 

pressures (50 F to 550 F and 5 to 500 psig). 

The screening data indicated that most process units at these facilities 

are characterized by equipment leak frequencies far below levels found by EPA 
P.8 

in studies conducted in the 1970's and 1980's. In addition, the data base 

indicated much lower leak frequencies at the phosgene process units than at 

the EO and BD units, and the EO units in general had lower leak frequencies 

than the BD units. Table 1 presents the plant-specific leak frequency data by 

component type, at various leak definitions for the three processes. The data 

shown in Table 1 are the screening data that were judged to be consistent with 

proper calibration and use of the test equipment. The screening values for 

the ten BD and nine EO process units were also adjusted for the instrument 

response factor to represent more accurately the screening concentration of 

equipment in BD or EO service. The data presented in Table 1 represent 

process units in various stages of control and operations. Some plants 

operated using formal LDAR programs and others did not; some units were 

screened just before a shutdown for maintenance and others were screened just 

after startup following a scheduled maintenance shutdown. 

Texas Air Control Board Data. Additional data from three plant sites 

were provided by the Committee member representing the Texas Air Pollution 

Control Board. These plants are subject to a Texas regulation that requires 

leak detection and repair (LDAR) with directed maintenance at a 500 ppmv leak 

definition. This requirement has been applied as part the permit program for 

new and modified sources. Data were provided for cumene, phenol/acetone, and 

butyraldehyde/butanol process units which had been operating a 500 ppm LDAR 

program for one to six quarters. These units had average leak frequencies at 

500 ppm for valves ranging from 0 to 3.6 percent, for pumps of 3.6, 4, and 5 

percent, and for flanges of 0 and 2 percent. These data show for several 

chemicals that a 500 ppm LDAR program is effective and will significantly 

decrease leak frequency. 

6 
P.9 

The above information, when compared with the earlier studies and 

analyses shows that the performance of available technology is better than 

that expected from a 10,000 ppm LDAR program. Moreover, like earlier studies, 

these studies do not identify any one single factor or technology as being 

responsible for the better performance. Rather, the recent data confirm that 

effective leak control involves a combination of factors. For example, 

statistical analysis of the recent EO and BD data failed to identify specific 

process parameters or equipment designs that alone significantly affected leak 

frequencies. 

In addition to considering the available screening data, the Committee 

visited 3 integrated chemical plants; 1 large integrated chemical plant had 20 

operating units including a phosgene unit, a toluene diisocyanate unit, and a 

hydrogen fluoride unit. One conclusion drawn from these visits was that the 

acute toxicity of phosgene and toluene diisocyanate has resulted in the 

routine use of a number of effective leak control practices in these process 

units. Measures taken to prevent and minimize leaks in phosgene and 

isocyanate units include design to minimize the number of components, 

stringent quality assurance/control programs, bench testing of equipment for 

leaks, and careful management and extensive continuous monitoring of the unit 

to detect leaks and problems. In addition,,phosgene and isocyanate units are 

shut down for immediate repair whenever any leak is detected. Immediate 

shutdown is possible because phosgene and isocyanate process units are small 

and are not operated as part of an integrated process. In units where less 

acutely toxic compounds are used or produced, such measures were not observed 

and the units are not immediately shut down for repair whenever a leak is 

detected. Rather, these units are typically operated for a fixed time period 
P.10 

before they are shut down for maintenance and repair. Representative 

operating times between scheduled shutdowns range from 6 months to several 

years, with typical time between turnarounds of approximately 3 years. 

The Committee also concluded that equipment design and an on-going 

quality control/assurance program has a significant role in achieving low leak 

frequencies. This conclusion was supported by-remarks made to the Committee 

by a chemical industry representative who described his company's recent 

experience with two ethylene oxide production units. Following completion of 

a screening study, the company undertook a program to reduce the leak 

frequency and emissions from the units. Steps taken consisted of component 

inspection, complete or partial replacement of over 700 valves and 2000 

gaskets, modification of design to reduce leaks, and regular monitoring and 

inspection for leaks. The company reported that there was an overall 

reduction of about 80 percent in the number of leaking components following 

completion of this project. 

Committee Analysis and Consideration of the Data 

The Committee considered the data and information described in the 

preceding section and concluded that the EO, BD, and Phosgene data should 

serve as the principle basis for establishing the performance of MACT for 

SOCMI processes. The EO, BD, and Phosgene data, however, were considered in 

light of the broader data; especially, the Texas 500 ppm LDAR program and the 

site visits. On this basis, the Committee agreed that phosgene units are not 

similar in design, operation, and maintenance to most SOCMI processes. Some of 

the maintenance and operating practices for phosgene units control programs 

went beyond maximum available control technology (MACT) for other SOCMI 

processes. Specifically, the practice of immediate shut down is economically 

8 
P.11 

and technically infeasible for other processes because shut down of the one 

unit would require shut down of all the integrated operations at the site and 

it would be impractical to clear large volumes of chemicals in short time 

frames. In some cases, emissions from clearing process material from part or 

all of the units could greatly exceed the emissions that would result from the 

leaking equipment. Therefore, while the phosgene units performance did 

provide an indication of the potential for leak reduction, the Committee 

concluded that the EO and BD units are more representative of the range of 

processes in SOCMI than are phosgene or toluene diisocyanate units. The 

Committee did recognize, as indicated by the framework and the performance 

levels, that very low leak frequencies are generally achievable and that the 

rule should encourage attaining low emissions. 

From the data and observations, the Committee also concluded that low 

emission performance results from combinations of monitoring (or 

surveillance), repair of leaking equipment, use of quality assured and quality 

controlled equipment suitable for the process operating conditions, and a 

quality controlled maintenance and repair program. The Committee concluded 

that such combinations are MACT for SOCMI processes. The information 

available did not identify any single factor, such as particular equipment 

design or specific work practices or maintenance programs that by itself would 

guarantee low emission performance in all cases. Furthermore, the Committee 

did not identify the results at any one specific process unit or performance 

level as representing MACT performance because there is no apparent break 

point that represents a limit of what is achievable with a combination of 

technologies that are available. Thus, the Committee identified the best 

performing EO process units, the EB/S unit, the Texas 500 ppm units, and 
P.12 

possibly the best performing BD process units as reflecting the performance of 

MACT for toxic chemical processes. 

Regulatory Approach 

Because available information indicated that best performance for 

equipment leaks could not be defined or reflected in a single numerical 

standard, type of technology, or group of work practices, the Committee 

focused on developing a regulatory framework that, when combined with 

performance levels, would reflect MACT. Key principles that evolved and that 

led to the regulatory framework are: 

(1) Motivation is a major factor determining performance. Incentives 

should be included in the standard to reward good performance and prescribed 

corrective actions should be included to ensure poor performance is corrected 

in a timely manner. 

(2) Flexibility in achieving specified results is important. This is 

necessary to allow consideration of process to process variations in operating 

conditions and equipment specifications and to provide incentives for 

identifying the most effective combination of equipment and practices. 

(3) Time has to be provided for sources to identify, implement, and 

design systems to meet the specified results. Effective control requires 

continual analysis and adjustment and may involve several technologies which 

cannot be identified or applied at one time or in one step. 

(4) More frequent monitoring and maintenance or a prescribed program 

should be employed, at a minimum, for those process units that do not achieve 

the specified results through a program of their own design or through 

quarterly inspection and maintenance alone. 

(5) There is insufficient information available to set a not-to-be10 
P.13 

exceeded standard. The existing information is too limited in scope to 

predict what level of performance could be achieved by processes for which no 

data were available. 

The majority of the Committee deliberations concerned development of a 

regulatory framework and performance levels that would incorporate the above 

key principles, while reflecting the performance of MACT. These deliberations 

primarily focused on developing provisions for valves, pumps, and flanges 

because these emission sources offered the greatest potential for emission 

reductions. The Committee used the existing LDAR program as a starting point 

for development of the framework for these sources. Early-on, the Committee 

recognized the need for a phased-in approach for valves and pumps that would 

provide time for plants to develop and implement effective programs and to 

focus on larger emission sources first. The agreed approach defines MACT for 

valves and pumps as consisting of three phases of increasing stringency. The 

phase-in approach is necessary because effective control requires continual 

analysis and adjustment of programs as experience is gained. Therefore, each 

phase, as it occurs reflects the performance of MACT for units in that phase. 

The Committee also deliberated on several methods of linking monitoring 

frequency with performance and of providing incentives to use low emission 

equipment or to reduce the amount of equipment in VHAP service. The final 

decision was to link reduced monitoring frequency with lower leak frequencies, 

and to give credit for removal of equipment or use of low leak design 

equipment. This approach is consistent with the data which indicate that 

there are combinations of technology, maintenance practices, and quality 

assurance programs that can achieve very low leak frequencies while using less 

frequent monitoring intervals. 

11 

•.• 
P.M 

The Committee also debated whether to require shut down of process units 

for repair of leaking equipment whenever performance deteriorates below some 

performance level. The Committee ultimately concluded that process units 

should not be shut down to meet a performance level. It was generally agreed 

that clearing of process materials could cause greater emissions than delaying 

repairs until the next scheduled shutdown. 

The Committee also agreed to retain the existing equipment standards for 

pressure relief devices, sample points, open-ended lines, product accumulator 

vessels, and compressors. The existing standards for these items of equipment 

require installation of equipment or control devices and essentially eliminate 

emissions from equipment leaks. The Committee considered these requirements 

to be MACT. 

For the valve, pump, and connector standards, the Committee primarily 

used the data from the better performing EO units, the best performing BD 

units, the Texas 500 ppm units, and the EB/S unit to establish the performance 

levels for the monitoring frequency. A major consideration in the selection 

of performance levels was the understanding.that the levels are interrelated 

with the framework and phasing and are not necessarily the levels that would 

have been chosen for a not-to-be-exceeded framework. In the case of the valve 

standard, the selection of the performance levels was also influenced by the 

inclusion of provisions that provide an alternative to monthly monitoring. 

Referred to as the Quality Improvement Program (QIP), this program ensures 

that plants subject to these provisions install low emission performing 

replacement equipment (during normal replacement) and implement a quality 

assurance/control program to ensure that all elements of MACT are utilized. 

Also, the QIP was included in the framework to allow those process units that 

12 
P.15 

do use all elements of MACT but do not achieve the specified numerical 

performance levels for less frequent monitoring to remain on a quarterly 

monitoring schedule. 

The basis for the specific provisions and performance levels selected 

for each type of equipment is discussed below. 

Valves. For valves the Committee initially considered both equipment 

standards and LDAR programs and ultimately agreed upon a three phase LDAR 

program. Initially, the Committee considered requiring the use of equipment 

such as sealed bellows valves because the equipment is often believed to have 

zero emissions. This option was not selected for several reasons. First, 

these valves are not suitable for use in all operating conditions and services 

encountered in SOCMI processes. Specifically, these valves can not be used in 

corrosive streams, with gritty materials, or in extremely high pressure or 

temperature conditions. Second, sealed bellows valves can leak internally, 

and will eventually fail. When failure occurs, there is potential for massive 

leaks. Due to this possibility for leaks, monitoring of these valves is 

necessary. Considering this, the Committee thought that the leak detection, 

repair, and performance standards framework described above would best reflect 

MACT. This approach allows and would give credit for any low emission 

performing valve regardless of its' design. 

The Committee considered several LDAR programs which tied monitoring 

frequency to the performance level achieved and created a framework that 

consists of several combinations of work practices and performance levels. In 

determining the maximum monitoring frequencies for Phase III, the Committee 

considered requiring weekly monitoring and monthly monitoring. The weekly 

monitoring program was rejected as being impractical and unreasonable. The 

13 
Committee agreed that a monthly program was the maximum frequency that would 

be generally feasible, and would reduce emissions, while being sufficiently 

costly to cause sources to identify more cost-effective approaches. For plants 

that do not achieve the performance level for quarterly monitoring, the 

standard requires monthly monitoring or participation in the QIP program for 

valves. In addition, the Committee also decided to allow less frequent 

monitoring to provide an incentive to achieve better performance than that 

required for the base quarterly monitoring program. Annual and semi-annual 

frequencies were selected for the incentive programs. 

In selecting the performance level and leak definition, the Committee 

considered the performance of the better performing EO units (and possibly the 

best BD units) and the performance of the units subject to the Texas 500 ppm 

standard. Using these data, the Committee considered leak definitions in the 

range of 50 to 1000 ppm and performance levels from 1 to 5 percent leaking 

valves. These data and the fact that, in practice, low leak frequencies were 

achieved by a 500 ppm LDAR program alone supported the practicality and 

achievability of a performance limit for a quarterly LDAR program of 2 percent 

leaking valves at a 500 ppm leak definition. Leak definitions lower than 500 

ppm were not selected due to uncertainties about the practical ability to 

measure and repair smaller leaks. Concentrations greater than 500 ppm were 

not selected in light of data demonstrating the practicality of a 500 ppm LDAR 

program. The Committee also agreed that units with less than 1 percent leaking 

valves could monitor the valves semiannually and those with less than 0.5 

percent leaking valves could monitor annually. These performance levels were 

selected considering the Committee had previously agreed to exclude 

nonrepairable valves (up to a maximum of one percent of the total valve pool) 

14 
P.17 

from the calculation of percent leaking- see section E.3 of this notice for 

discussion of the basis for the nonrepairable provision. These performance 

levels have been demonstrated by the better performing EO process units, the 

EB/S unit, and by the plants subject to the Texas 500 ppm regulation. The 

Committee considered these levels to reflect the best performance of 10 

percent of the units and to represent the performance of MACT. 

Pumps. In deliberations on the standard, the Committee considered the 

data summarized in Table 1, additional analyses of the EO/BD data, and the 

comments of pump seal manufacturers. The EO/BD data showed pump leak 

frequencies and overall performance to be highly variable with leak 

frequencies ranging from 0 to 50 percent at a 1000 ppm leak definition. 

Additional analyses were done to compare the performance of dual mechanical 

seal (DMS) and single mechanical seal (SMS) pumps. These comparisons showed 

that, in general, DMS pumps screened at 0 ppm and that SMS pumps performance 

varied widely among the process units. In some cases, the SMS pumps screened 

at less than 100 ppm and could be viewed as having comparable performance to 

that of DMS pumps. For the majority of SMS pumps screening at less than 10,000 

ppm, the screening values were fairly uniformly distributed from 100 to 9100 

ppm. Thus, the data did not provide a clear indication of the performance 

level that can be achieved by SMS without incurring high maintenance costs. 

From its consideration of the available data, the Committee generally 

concluded that,, as a group, pumps equipped with DMS have lower leak 

frequencies than those equipped with SMS. Consequently, the Committee 

deliberated at great length on whether MACT is reflected by an equipment 

standard for DMS on all pumps or by a performance standard. The Committee 

decided not to establish an equipment standard because DMS are not suitable 

15 
P.18 

Table 1: Summary of Equipment Screening Data 

Unit ID 

EO 1 

EO 2 

EO 3 

EO 4 

EO 5 

EO 6 

EO 7 

EO 8 

EO 9 

BD 1 

BD 3 

BD 4 

BD 5 

BD 6 

BD 7 

BD 8 

BD 10 

BD 11 

BD 12 

Acrolein 

TACB 

A 

B 

C 

Average 

SOCMI 

at 10,000 

Valves % 

250 

0.6 

2.8 

1.4 

2 

0.4 

1.6 

1.2 

2.9 

5.3 

10.7 

5.6 

7.3 

11 

7.5 

2.2 

21.9 

25 

11.3 

5.9 

0.1 

ppm 

500 

0.4 

2.2 

1.1 

1.3 

0.2 

1.4 

1.2 

2.5 

4.5 

8.8 

4.8 

6.3 

7.7 

5.4 

2.2 

18.4 

19.8 

10.1 

4.5 

0.1 

3.6 

0 

0.7 

11.5 

Leakers 

1000 

0.3 

1.1 

1.1 

0.9 

0.2 

1.3 

1.2 

1.5 

4 

7.5 

4.2 

5.4 

5 

3.3 

2.2 

15.1 

17.1 

8 

3.7 

0.1 

Pumps % 

500 

0 

23 

36 

0 

0 

6 

25 

24 

2.9 

50 

33 

n/a 

58 

0 

16.7 

10 

4 

4 

4 

5 

1000 

0 

18 

27 

0 

0 

0 

25 

21 

0 

n/a 

50 

0 

16.7 

10 

4 

Leakers 

2000 

0 

14 

9 

0 

0 

0 

25 

15 

0 

n/a 

41.7 

0 

16.7 

10 

4 

9 

5000 

0 

9 

9 

0 

0 

0 

25 

13 

0 

n/a 

41.7 

0 

16.7 

10 

4 

Connectors % 

250 

0 

0.9 

3.2 

2.8 

0 

4.1 

0 

2.5 

7.6 

0 

0.7 

10 

3.4 

n/a 

0 

7.4 

5.1 

1.4 

0.6 

0.1 

500 

0 

0.9 

3.2 

1.5 

0 

4.1 

0 

2.5 

5.9 

0 

0.7 

8.6 

1.5 

n/a 

0 

6.7 

2.5 

1.4 

0.6 

0.1 

0 

n/a 

2 

2.1 

Leakers 

1000 

0 

0.9 

3.2 

0.7 

0 

4.1 

0 

2.5 

4.9 

0 

0.7 

7.1 

1.1 

n/a 

0 

5.9 

1.9 

0.7 

0.6 

0.1 
P.19 

for use in all cases and because a DMS equipment standard would be very costly 

and would preclude effective lower cost options. Dual mechanical seals can not 

be used with materials where leakage of the barrier fluid would affect product 

purity, with polymerizing monomers, or on reciprocating pumps. Also, the pump 

casing of some existing packed seal and SMS pumps does not allow installation 

of a DMS assembly. In such cases, a DMS equipment standard would require 

replacement of the entire pump. The cost of a DMS equipment standard was 

considered only in a general sense; estimates of the cost of pump replacements 

and the cost of installation of DMS systems were not the subject of Coiranittee 

discussions. The opinion that a DMS equipment standard would be very costly 

was based on general knowledge and the experience of some Committee members. 

However, to give all Committee members some perspective on the potential 

costs, EPA provided an estimate of the annualized cost for retrofitting an 

existing pump with a DMS system. This estimate showed the cost would be 

approximately $2,200/year (1990 dollars) for each pump. In previous 

rulemakings, EPA has estimated that a requirement of DMS on pumps has an 

incremental cost effectiveness over a 10,000 ppm LDAR program of 

$5,600/megagram of total VOC (1978 dollars), which is comparable to 

approximately $15,000/megagram in current dollars. Some Committee members 

expressed an additional concern that a DMS equipment standard would have 

significant economic effects on small producers. Since the Committee thought 

a performance standard could be developed for pumps, the expected costs of a 

DMS equipment standard were not evaluated. 

To establish a performance standard that would reflect MACT for pumps, 

the Committee considered the performance capabilities of SMS (and packed 

seals) compared to the performance, applicability, and cost of DMS. 

16 
Discussions among the Committee members, chemical industry representatives, 

and pump seal manufacturers lead to the conclusion that it is not possible to 

identify precisely best performance levels achievable by SMS and that, 

although advances in technology could reasonably be expected over the next 5 

years, the limits on these advances could not be established. Because of 

technical limitations on the use of DMS on pumps in food/medical service and 

the use of mechanical seals on pumps handling polymerizing monomers, the 

Committee agreed to establish separate performance standards for pumps in 

those two services. 

For pumps in general service, the Committee agreed that 1000 ppm 

represented a performance target reflecting MACT and that repair of pumps with 

a leak rate less than 2000 ppm would result in significant and costly 

maintenance, without any attendant emission reduction. Therefore, 2000 ppm 

was established as the concentration at which repair is required. The 

Committee also concluded that a 10 percent leak frequency (or 3 leaking pumps) 

is the appropriate point to impose a quality improvement program that includes 

a mandatory replacement provision. On balance, it was believed that this 

combination of requirements would provide the time and incentive needed to 

achieve best performance from SMS, would allow use of SMS where they can 

achieve low emissions, and would allow use of both SMS and DMS pumps, as 

appropriate, to achieve the standard. 

For pumps in food/medical service, the Committee selected 2000 ppm and 

10 percent leak frequency as the performance level. The leak definition was 

set at 2000 ppm to account for the limited applicability of DMS pumps and the 

uncertainty that SMS seals could achieve lower performance levels without 

excessive replacements in this service. The Committee also agreed that 

17 
P.21 

processes with pumps in food/medical service that exceed 10 percent leaking 

pumps would not be subject to the mandatory replacement provisions in the 

quality improvement program. 

For pumps handling polymerizing monomers, the Committee selected 5000 

ppm and 10 percent leak frequency for the performance level. This decision was 

based on the lack of data and uncertainties on tbe limits of performance of 

SMS or packed seals in this service. It was also agreed that facilities that 

exceed 10 percent leak frequency would not be subject to the mandatory 

replacement provision of the quality improvement program. 

Connectors. Provisions for a LDAR program for connectors were developed 

after the Committee generally agreed that connectors could be a significant 

source of emissions at a well-controlled plant and that emissions could be 

reduced. In the development of these provisions, the Coiranittee considered the 

data summarized in Table 1 and the contribution of connector emissions to 

total emissions for several EO/BD process units. These data showed connector 

leak frequencies as high as 3 percent, at a leak definition of 10,000 ppm, and 

contribution the majority of the total emissions. Because some EO/BD units 

had 0 percent leaking connectors at various leak definitions, including 250 

and 10,000 ppm, the Committee concluded that connector leaks can be controlled 

to low levels. The general view was that the relatively high leak rates 

observed at some process units was a result of infrequent or no inspections 

and maintenance. A LDAR program was established to ensure that low leak 

frequencies are attained. 

In development of these provisions, the Committee agreed that LDAR can 

reduce connector leak frequencies and that assuring MACT performance requires 

less frequent monitoring than is necessary for pumps or valves. Less frequent 

18 
monitoring is needed because flanges and other connectors have no moving parts 

and once repaired they should remain leak free for extended periods. 

Information provided by industry members on the Committee indicated that a 

number of actions can be taken to reduce or eliminate leaks. In most cases, it 

was expected that tightening the flange bolts would eliminate the leak. It was 

also expected that in other cases it may be necessary to replace the gasket or 

to correct faulty alignment of surfaces. These latter cases are expected to be 

relatively infrequent. The Committee, therefore, decided that an annual base 

program was the maximum frequency that was reasonable. The Committee also 

concluded that process units that demonstrate sustained performance at the 

level of the standard should be allowed to monitor less frequently than 

annually. This concept is similar to the skip-period provisions for valves in 

the existing equipment leak regulations. This approach is consistent with 

quality control principles and the Committee concluded that this approach will 

ensure MACT performance. 

The Committee selected the performance level and leak definition 

considering the data from the EO/BD units, the Texas 500 ppm LDAR units, and 

the general conclusions drawn from the Committee's discussions. These data 

and the fact that, in practice, low leak frequencies were achievable persuaded 

the Committee that a leak definition of 500 ppm and a performance limit of 0.5 

percent leaking connectors would reflect MACT. Process units that have 0.5 

percent, or greater, leaking connectors are required to implement an annual 

LDAR program for connectors. Process units that have less than 0.5 percent 

leaking connectors are allowed to monitor all connectors in a biennial or 

quadrennial program. 

19 

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