p.1 

OAR Box 1168 

Prepped by Ollie Stewart 

Document Number: 

102) ll-C-31 

Docket Number: 

A-89-10 

Printed 4/29/2008 11:23:20 AM Sheet 102 of 131 
P.2 

,rosr'% 

*"( OR0*<t 

A-89-10 

UNITED STATES ENVIRONMENTAL PROTECT 

Office of Air Quality Planning and Star 

Research Triangle Park, North Carolina __//"!. 

OCT 1 2 1990 

II-C-31 

Dear Reg Neg Committee: 

Enclosed for your review and comment is the draft preamble section on 

the use of the data and the outline for the advance notice of proposed 

rulemaking (ANPR). This section is being circulated for early review to ensure 

it reflects the Committee's thinking and because of interest expressed by 

several members. 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 in the next week. 

As noted in the September 27 mailout, we are aiming to complete the 

entire ANPR in November. Consequently, we would appreciate receiving your 

comments on this section of the ANPR no later than OCTOBER 22. If you have any 

questions on the draft section or on progress, please don't hesitate to call. 

Sincerely, 

Jan/Meyer 
P.3 

/0li*-/9o 

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 
P.4 

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

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, and motivation, quality, and other 

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

achieve particular performance levels or to install new 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. 

These data are 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. 

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 many facilities had no 

leaking valves or pumps and no facilities had more than 1.5 percent leaking 

valves or more than 12.5 percent leaking pumps. The average leak frequencies 

were 0.27 percent for valves and 2.3 percent for pumps. These leak 
P.5 

frequencies, in general, are lower than the average frequencies of 3 to 5 

percent for valves and approximately 10 percent for pumps 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 

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 
P.6 

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 average leak frequencies of 33 

percent for pumps, 16 percent for light liquid valves,.27 percent for gas 

valves, and 0.4 percent for flanges and other connectors. The data for unit 2 

showed leak frequencies of 5.6 percent for pumps, 0.8 percent for light liquid 

valves, 1 percent for gas valves, and 0.1 percent for flanges and other 

connectors. The data for unit 2 indicate that technology is available to 

reduce leaks and suggest that motivation is an important factor 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 process units subject to the 

benzene equipment leak NESHAP. Screening data were provided for roughly 2500 

components. These data showed an average percent leaking valves, percent 

leaking pumps and percent leaking flanges at a leak definition of 10,000 

ppm. This facility consists of an ethylbenzene/styrene process unit, and 

is approximately years old. 
P.7 

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 (EO), and phosgene production process units, 

he 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 1ines 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. In general, particular care was taken in measurements of equipment 

with near zero or less than 200 ppm emissions. These data are the most 

comprehensive data available that document the full range of leak frequencies 

for large numbers of process units used for the production of specific 

chemicals. 

The screening data indicated that most process units at these facilities 

are characterized by equipment leak frequencies far below levels found by EPA 

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 leak definitions of 50, 500, 1000, and 10,000 ppm for the 

three processes. Table 1 does not include data for E0 and BD process units 

! 
P.8 

that were judged by the Committee to be inconsistent with proper calibration 

and use of the test equipment. The data presented in Table 1 represents plants 

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 

scheduled maintenance shutdown. 

Texas Air Control Board Data. Additional data from 3 plants 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. These plants had previously been subject to a 10,000 ppm LDAR 

program. The data provided were 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. More particularly, these data 

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

decrease leak frequency across a range of chemicals. 

The above data, when compared with the earlier studies and analyses show 

that the performance of available technology is better than that expected from 

a 10,000 ppm LDAR program. However, 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 E0 and BD data failed to identify specific process parameters or 
P.9 

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 observation made from these visits was that the 

much greater motivation to control leaks in phosgene and isocyanate units has 

resulted in the routine use of a number of effective leak control practices in 

these 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 

shutdown for immediate repair whenever any leak is detected. In units where 

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

observed and the units are not immediately shutdown for repair whenever a leak 

is detected. Rather, these units are typically operated for a fixed time 

period before they are shutdown 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 
P.10 

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

inspection, replacement of over 700 valves and 2000 gaskets, modification of 

design to reduce leaks, and regular monitoring and inspection for leaks. 

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 E0, BD, and Phosgene data should 

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

SOCMI processes. The E0, 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 shutdown is economically 

and technically infeasible for other processes because shutdown of the one 

unit would require shutdown of all the integrated operations at the site and 

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

frames. Therefore, while the phosgene units performance did provide an 

indication of the potential for leak reduction, the Committee concluded that 

the E0 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 

8 
P.11 

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 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. 
(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) 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-beexceeded 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 

10 
P.13 

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. 

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 "state of art" or MACT. 

For the valve, pump, and flange standards, the Committee used the data 

from the better performing EO 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-to11 
P.M 

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 protect those process units that do use all elements of MACT 

but do not achieve the specified numerical performance levels required 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 leaks. 

Due to this possiblity 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 

12 
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 

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

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

costly to motivate 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 provide incentives for 

better performance than the base limit for quarterly monitoring. The 

incentives provided are annual and semi-annual monitoring frequencies, for 

achieving specified performance levels. 

In selecting the performance level and leak definition, the Committee 

considered the performance of the better performing EO and BD units and the 

performance of the units subject to the Texas 500 ppm standard. Using this 

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 

13 

LMI 
P.16 

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 the 

demonstrated 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 have been demonstrated by the better 

performing E0 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 T, 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. 

14 
P.17 

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 

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

and would preclude effective lower cost options. Examples of cases where DMS 

are not suitable for use with materials where leakage of the barrier fluid 

could affect product purity, with polymerizing monomers, or on reciprocating 

pumps. In cases where DMS can be used, the cost of installation of the dual 

seals and degassing vents is estimated to be $8,200 (1989) for an existing 

pump and $7,600 (1989) for a new pump. The annualized cost is estimated to be 

$2,200/yr for an existing pump and $l,800/yr for a new pump. This control 

would reduce emissions by approximately 0.1 Mg/yr beyond that achieved by a 

10,000 ppm LDAR program and would have an incremental cost effectiveness of 

approximately $14,500 to $17,500/Mg for new and existing pumps (Note: These 

numbers are preliminary and represent the incremental cost from a 10,000 ppm 

LDAR program to roughly a 500 ppm program. We are still considering how this 

incremental C/E should be calculated.). The additional emission reduction 

achievable through use of DMS pumps is typically very small (e.g.less than 5 

percent) relative to the total emissions from the process unit. 

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. 

15 
P.18 

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 

limitations on the applicability of DMS, the Committee agreed to establish 

separate performance standards for pumps in food/medical service and for pumps 

handling polymerizing monomers. 

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 be 

used with low emissions, and would allow use of both SMS and DMS pumps at 

those facilities where some processes are incompatible with DMS pumps. 

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 

uncertainty that SMS seals could achieve lower performance levels without 

excessive replacements in this service. The Committee also agreed that 

16 
P.19 

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

leaking pumps limitation 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 the 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. 

Flanges. Provisions for a LDAR program for flanges were developed after 

the Committee concluded that flanges could be a significant source of 

emissions at a well-controlled plant and emissions could be reduced. In the 

development of these provisions, the Committee considered the data summarized 

in Table 1 and the contribution of flange emissions to total emissions for 

several EO/BD process units. These data showed flange leak frequencies as high 

as 3 percent, at a leak definition of 10,000 ppm, and up to -- percent of the 

total unit from flange emissions. Because some EO/BD units had 0 percent 

leaking flanges at 100 and at 10,000 ppm leak definitions, the Committee 

concluded that flange 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. 

In development of these provisions, the Committee agreed that control 

measures are available for flange leaks and that assuring MACT performance 

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

frequent monitoring is needed because flanges have no moving parts and once 

17 
P.20 

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 less frequent monitoring should be allowed for sources that 

demonstrate sustained performance at the level of the standard. 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 Coiranittee 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 fron the Committee's discussions. These data 

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

the Committee to define a leak as 500 ppm and to set a performance limit of 

0.5 percent leaking flanges reflected MACT. Process units that have 0.5 

percent, or greater, leaking flanges shall implement an annual LDAR program 

for flanges. Process units that have less than 0.5 percent leaking flanges 

shall monitor all flanges in a biennial or quadrennial program. 

18 
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 

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 

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 

% 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 

Table 1 

Pimps % 

500 

0 

23 

36 

0 

0 

6 

25 

24 

2.9 

50 

33 

n/a 

58 

0 

16.7 

10 

1000 

0 

18 

27 

0 

0 

0 

25 

21 

0 

n/a 

50 

0 

16.7 

10 

Sunmary of 

Leakers 

2000 

0 

14 

9 

0 

0 

0 

25 

15 

0 

n/a 

41.7 

0 

16.7 

10 

5000 

0 

9 

9 

0 

0 

0 

25 

13 

0 

n/a 

41.7 

0 

16.7 

10 

Equipment Sa 

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 

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 

reening Da 

% 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 

Acrolein 0.1 0.1 0.1 0.1 0.1 0.1 

TRCB 

A 

B 

C 

3.6 

0 

0.7 

0 

n/a 

2 

Average 

SOCHI 

at 10,000 ppm 

11.5 2.1 

ho 
P.22 

• z^- R££ MEfi

 m^ OUTLINE 

I. Summary 

Brief suRonary of purpose of ANPR. 

II. Docket 

III. Further Information Contacts 

IV. Supplementary Information 

A. Summary of Standards 

B. Background 

1.Overview of equipment leaks significance and history of 

regulations 

2. Legal framework under Clean Air Act of 1990 

3. Brief description of the HON 

This will describe the overall scope of the HON and explain that the 

Negotiated rule is one of several for the 5 emission points. 

4. History of the Negotiation Coiranittee 

5. Coiranittee members 

C. Scope and Applicability 

1. Chemicals and processes 

2. Equipment 

Equipment covered by the rule 

Discussion of body flanges and why not covered 

3. API limitations language 

D. Data and Information Considered in the Development of the Negotiated 

Rule 

E. Basis for Negotiated Standard 

1. Applicablity 

Tints in use 

Percent VHAP cutoff 

Pilot Plants 

/ 

; 

_•___•_____• 
•• p 

^=$©w versus existing plants 

2. Compliance Dates (staggered implementation) 

3. Valve standard 

This will summarize the phases of the standard, the performance 

levels, etc that were explained in Section D. It will explain the basis for 

the other provisions in the valve standard. 

4. Pump standard 

This will be organized similarly to the discussion of the valve 

standard. 

i 

i 

5. Quality Improvement Program 

Valves 

Pumps 

6. Flanges and other connectors 

7. Other equipment 

Compressors 

OELs 

PRVs 

Sample 1ines 

Closed vent systems and control devices 

Agitators 

Instrumentation systems 

8. Alternative standards 

Equivalency 

Batch processes 

Enclosed evacuated building 

9. Test Methods and Procedures 

10. Delay of repair 

11. Recordkeeping and Reporting 

__________•