Leak Detection and Repair 

A Best Practices Guide 
United States 

Environmental Protection Agency 

Office of Compliance 

Office of Enforcement and Compliance Assurance 

1200 Pennsylvania Avenue, NW 

(mail code) 

Washington, DC 20460 
Disclaimer 

The U.S. Environmental Protection Agency (EPA) has reviewed this document and approves it for publication. This 

document does not constitute rulemaking by the EPA and may not be relied on to create a substantive or procedural right 

or benefit enforceable at law or in equity, by any person. The EPA may take actions at variance with this document and its 

internal procedures. 

Contents 

1.0 	 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1


2.0 	 Why Regulate Equipment Leaks? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2


3.0 	 Sources, Causes And Control Of Equipment Leaks . . . . . . . . . . . . . . . . . . . . . 3


3.1 	 How are emissions from equipment leaks reduced? . . . . . . . . . . . . . . . 3


3.2 	 What regulations incorporate LDAR programs? . . . . . . . . . . . . . . . . . . . 6


4.0 	 What Are the Benefits of an LDAR Program? . . . . . . . . . . . . . . . . . . . . . . . . . . 7


4.1 	 Reducing Product Losses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8


4.2 	 Increasing Safety for Facility Workers and Operators . . . . . . . . . . . . . . . 8


4.3 	 Decreasing Exposure for the Surrounding Community . . . . . . . . . . . . . . 8


4.4 	 Potentially Reducing Emission Fees . . . . . . . . . . . . . . . . . . . . . . . . . . 8


4.5 	 Avoiding Enforcement Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8


5.0 	 Elements of an LDAR Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9


6.0 	 What Compliance Problems Have Been Found With Current LDAR


Programs? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15


7.0 	 Model LDAR Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19


7.1 	 Written LDAR Program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20


7.2 	 Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20


7.3 	 LDAR Audits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21


7.4 	 Contractor Accountability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22


7.5 	 Internal Leak Definition for Valves and Pumps . . . . . . . . . . . . . . . . . . 22


7.6 	 More Frequent Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23


7.7 	 Repairing Leaking Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23


7.8 	 Delay of Repair Compliance Assurance . . . . . . . . . . . . . . . . . . . . . . . 24


7.9 	 Electronic Monitoring and Storage of LDAR Data . . . . . . . . . . . . . . . . 24


7.10 	 QA/QC of LDAR Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25


7.11 	 Calibration/Calibration Drift Assessment . . . . . . . . . . . . . . . . . . . . . . 25


7.12 	 Records Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26


8.0 	 Sources of Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Tables 

Table 3.1 Sources of equipment leaks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4


Table 3.2 Equipment component counts at a typical refinery or chemical plant. . . . 5


Table 3.3 Uncontrolled VOC emissions at a typical facility. . . . . . . . . . . . . . . . . . 5


Table 4.1 Control effectiveness for an LDAR program at a chemical process unit 


and a refinery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Leak Detection and Repair Compliance Assistance Guidance—A Best Practices Guide


Appendices 

Appendix A Federal Regulations That Require a Formal LDAR Program 

With Method 21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29


Appendix B Federal Regulations That Require the Use of Method 21 


But Do Not Require a Formal LDAR Program . . . . . . . . . . . . . . . . . . . 30


Appendix C Method 21 General Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31


Appendix D Method 21—Determination of Volatile Organic Compound Leaks . . . . . 32


Appendix E Summary of NEIC Comparative Monitoring Results of 


Leaking Valves at 17 Refineries . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39


Appendix F Enforcement Alert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40


Leak Detection and Repair—A Best Practices Guide


1.0 Purpose 

In general, EPA has found signifi cant widespread 

noncompliance with Leak Detection and Repair 

(LDAR) regulations and more specifi cally, noncompliance with Method 21 requirements. In 1999, EPA 

estimated that, as a result of this noncompliance, 

an additional 40,000 tons of VOCs are emitted annually from valves at petroleum refi neries alone. 

This document is intended for use by regulated 

entities as well as compliance inspectors to identify 

some of the problems identified with LDAR programs focusing in on Method 21 requirements and 

describe the practices that can be used to increase 

the effectiveness of an LDAR program. Specifi cally, 

this document explains: 

• 	The importance of regulating equipment 

leaks; 

• 	The major elements of an LDAR program; 

• 	 Typical mistakes made when monitoring to 

detect leaks; 

• 	 Problems that occur from improper management of an LDAR program; and 

• 	 A set of best practices that can be used to 

implement effective an LDAR program. 

Some of the elements of a model LDAR program, 

as described in Section 7.0, are required by current 

Federal regulations. Other model LDAR program 

elements help ensure continuous compliance although they may not be mandated from a regulatory standpoint. Furthermore, State or local requirements may be more stringent than some elements 

of the model LDAR program, such as with leak 

definitions. Prior to developing a written LDAR 

program plan, all applicable regulations should be 

reviewed to determine and ensure compliance with 

the most stringent requirements. 

1

According to EPAs 2002 National Emissions 

Inventory (NEI) database, 125,000 tons per year 

(tpy) of VOC are emitted from petroleum refiner

ies. It is estimated that over 49,000 tpy of VOC 

from refineries are equipment leak emissions.

Of the 165,000 tpy of VOC emissions from 

chemical manufacturing facilities, 21,000 tpy is 

attributable to equipment leaks.

Leak Detection and Repair—A Best Practices Guide


2.0 Why Regulate Equipment Leaks?


EPA has determined that leaking equipment, such 

as valves, pumps, and connectors, are the largest 

source of emissions of volatile organic compounds 

(VOCs) and volatile hazardous air pollutants 

(VHAPs) from petroleum refineries and chemical 

manufacturing facilities. The Agency has estimated 

that approximately 70,367 tons per year of VOCs 

and 9,357 tons per year of HAPs have been emitted 

from equipment leaks. Emissions from equipment 

leaks exceed emissions from storage vessels, wastewater, transfer operations, or process vents. 

VOCs contribute to the formation of ground-level 

ozone. Ozone is a major component of smog, and 

causes or aggravates respiratory disease, particularly in children, asthmatics, and healthy adults 

who participate in moderate exercise. Many 

areas of the United States, particularly those areas 

where refineries and chemical facilities are located, 

do not meet the National Ambient Air Quality 

Standard (NAAQS) for ozone. Ozone can be transported in the atmosphere and contribute to nonattainment in downwind areas. 

Some species of VOCs are also classified as VHAPs. 

Some known or suspected effects of exposure to 

VHAPs include cancer, reproductive eff ects, and 

birth defects. The highest concentrations of VHAPs 

tend to be closest to the emission source, where 

the highest public exposure levels are also often 

detected. Some common VHAPs emitted from refineries and chemical plants include acetaldehyde, 

benzene, formaldehyde, methylene chloride, naphthalene, toluene, and xylene. 

’ 

-

2

Leak Detection and Repair—A Best Practices Guide 

3.0 Sources, Causes And Control Of Equipment Leaks


A typical refinery or chemical plant can emit 600­

700 tons per year of VOCs from leaking equipment, 

such as valves, connectors, pumps, sampling connections, compressors, pressure-relief devices, and 

open-ended lines. 

Table 3.1 shows the primary sources of emissions 

from components subject to equipment leak regulations. In a typical facility, most of the emissions 

are from valves and connectors because these are 

the most prevalent components and can number in 

the thousands (Table 3.2). The major cause of emissions from valves and connectors is seal or gasket 

failure due to normal wear or improper maintenance. 

Previous EPA studies have estimated that valves 

and connectors account for more than 90% of emissions from leaking equipment with valves being the 

most significant source (Table 3.3). Newer information suggests that open-ended lines and sampling 

connections may account for as much as 5-10% of 

total VOC emissions from equipment leaks. 

3.1 	 How are emissions from equipment leaks 

reduced? 

Facilities can control emissions from equipment 

leaks by implementing a leak detection and repair 

(LDAR) program or by modifying/replacing leaking equipment with “leakless” components. Most 

equipment leak regulations allow a combination of 

both control methods. 

• 	 Leaks from open-ended lines, compressors, 

and sampling connections are usually fi xed 

by modifying the equipment or component. 

Emissions from pumps and valves can also be 

reduced through the use of “leakless” valves 

and “sealless” pumps. Common leakless 

valves include bellows valves and diaphragm 

valves, and common sealless pumps are diaphragm pumps, canned motor pumps, and 

magnetic drive pumps. Leaks from pumps 

can also be reduced by using dual seals with 

or without barrier fl uid. 

• 	 Leakless valves and sealless pumps are effective at minimizing or eliminating leaks, 

but their use may be limited by materials 

of construction considerations and process 

operating conditions. Installing leakless and 

sealless equipment components may be a 

wise choice for replacing individual, chronic 

leaking components. 

LDAR is a work practice designed to 

identify leaking equipment so that 

emissions can be reduced through repairs. A component that is subject to LDAR requirements must be 

monitored at specified, regular intervals to determine 

whether or not it is leaking. Any leaking component 

must then be repaired or replaced within a specified 

time frame. 

3

Leak Detection and Repair—A Best Practices Guide


Table 3.1 – Sources of equipment leaks.


Pumps are used to move fluids from one point to 

another. Two types of pumps extensively used in petroleum refineries and chemical plants are centrifugal 

pumps and positive displacement, or reciprocating 

pumps. 

Valves are used to either restrict or allow the movement of fluids. Valves come in numerous varieties and 

with the exception of connectors, are the most common piece of process equipment in industry. 

Connectors are components such as flanges and 

fittings used to join piping and process equipment 

together. Gaskets and blinds are usually installed 

between flanges. 

Sampling connections are utilized to obtain samples 

from within a process. 

Compressors are designed to increase the pressure of 

a fluid and provide motive force. They can have rotary 

or reciprocating designs. 

Pressure relief devices are safety devices designed 

to protect equipment from exceeding the maximum 

allowable working pressure. Pressure relief valves and 

rupture disks are examples of pressure relief devices. 

Open-ended lines are pipes or hoses open to the 

atmosphere or surrounding environment. 

Leaks from pumps typically occur at the seal. 

Leaks from valves usually occur at the stem or gland 

area of the valve body and are commonly caused by a 

failure of the valve packing or O-ring. 

Leaks from connectors are commonly caused from 

gasket failure and improperly torqued bolts on 

fl anges. 

Leaks from sampling connections usually occur at the 

outlet of the sampling valve when the sampling line is 

purged to obtain the sample. 

Leaks from compressors most often occur from the 

seals. 

Leaks from pressure relief valves can occur if the 

valve is not seated properly, operating too close to the 

set point, or if the seal is worn or damaged. Leaks 

from rupture disks can occur around the disk gasket 

if not properly installed. 

Leaks from open-ended lines occur at the point of the 

line open to the atmosphere and are usually controlled by using caps, plugs, and flanges. Leaks can 

also be caused by the incorrect implementation of the 

block and bleed procedure. 

4

Leak Detection and Repair—A Best Practices Guide


Table 3.2 – Equipment component counts at a typical 

refinery or chemical plant. 

Component Range Average 

Pumps 10 – 360 100 

Valves 150 – 46,000 7,400 

Connectors 600 – 60,000 12,000 

Open-ended lines 1 – 1,600 560 

Sampling connections 20 – 200 80 

Pressure relief valves 5 – 360 90 

Source: “Cost and Emission Reductions for Meeting Percent Leaker Requirements for HON Sources.” Memorandum to Hazardous Organic NESHAP 

Residual Risk and Review of Technology Standard Rulemaking docket. Docket 

ID EPA-HQ-OAR-2005-0475-0105. 

Table 3.3 – Uncontrolled VOC emissions at a typical facility.


Component Average Uncontrolled 

VOC Emissions (ton/yr) Percent of Total Emissions 

Pumps 19 3 

Valves 408 62 

Connectors 201 31 

Open-ended lines 9 1 

Sampling connections 11 2 

Pressure relief valves 5 1 

Total 653 

Source: Emission factors are from Protocol for Equipment Leak Emission Estimates, EPA-453/R-95-017, Nov 1995, and equipment counts in Table 3.2. 

More recent data 

indicates that openended lines and 

sampling connections 

each account for approximately 5-10% of 

total VOC emissions. 

5

For a comprehensive discussion of equipment 

leak regulation applicability determinations, see 

Inspection Manual: Federal Equipment Leak 

Regulations for the Chemical Manufacturing 

Industry, Vol. 1: Inspection Manual, EPA/305/B98/011 (Dec 1998), Chapter 2.

Leak Detection and Repair—A Best Practices Guide


3.2 	 What regulations incorporate LDAR 

programs? 

LDAR programs are required by many New Source 

Performance Standards (NSPS), National Emission 

Standards for Hazardous Air Pollutants (NESHAP), 

State Implementation Plans (SIPs), the Resource 

Conservation and Recovery Act (RCRA), and other 

state or local requirements. There are 25 federal 

standards that require facilities to implement 

LDAR programs. Appendix A shows the 25 federal 

standards that require the implementation of a formal LDAR program using Method 21. Appendix B 

lists 28 other federal regulations that require some 

Method 21 monitoring, but do not require LDAR 

programs to be in place. 

• 	 NSPS (40 CFR Part 60) equipment leak 

standards are related to fugitive emissions of 

VOCs and apply to stationary sources that 

commence construction, modifi cation, or 

reconstruction after the date that an NSPS is 

proposed in the Federal Register. 

• 	 NESHAP (40 CFR Parts 61, 63, and 65) equipment leak standards apply to both new and 

existing stationary sources of fugitive VHAPs. 

• 	 RCRA (40 CFR Parts 264 and 265) equipment 

leak standards apply to hazardous waste 

treatment, storage, and disposal facilities. 

• 	 Many state and local air agencies incorporate 

federal LDAR requirements by reference, but 

some have established more stringent LDAR 

requirements to meet local air quality needs. 

A facility may have equipment that is subject to 

multiple NSPS and NESHAP equipment leaks standards. For example, a number of manufacturing 

processes listed in the Hazardous Organic NESHAP (HON) equipment leak standard (40 CFR 63, 

Subpart H) may utilize equipment for which other 

NESHAP or NSPS equipment leak standards could 

apply (such as 40 CFR 60, Subpart VV). In addition, one process line may be subject to one rule 

and another process line subject to another rule. 

Facilities must ensure that they are complying with 

the proper equipment leak regulations if multiple 

regulations apply. 

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Leak Detection and Repair—A Best Practices Guide


4.0 What Are the Benefits of an LDAR Program?


When the LDAR requirements were developed, EPA 

estimated that petroleum refineries could reduce 

emissions from equipment leaks by 63% by implementing a facility LDAR program. Additionally, 

EPA estimated that chemical facilities could reduce 

VOC emissions by 56% by implementing such a 

program. 

Table 4.1 presents the control effectiveness of an 

LDAR program for different monitoring intervals 

and leak definitions at chemical process units and 

petroleum refi neries. 

Emissions reductions from implementing an LDAR 

program potentially reduce product losses, increase 

safety for workers and operators, decrease exposure 

of the surrounding community, reduce emissions 

fees, and help facilities avoid enforcement actions. 

Example – Emissions reductions at a typical SOCMI 

facility. 

Applying the equipment modifications and LDAR 

requirements of the HON to the sources of uncontrolled 

emissions in the typical facility presented in Tables 3.2 and 

3.3 would reduce the emissions per facility by approximately 

582 tons per year of emissions, an 89% reduction. 

Table 4.1 – Control effectiveness for an LDAR program at a chemical process unit and a refinery.


Equipment Type and Service 

Control Effectiveness (% Reduction) 

Monthly Monitoring

 10,000 ppmv 

Leak Definition 

Quarterly Monitoring 

10,000 ppmv Leak Defi nition 

500 ppm 

Leak Definitiona 

Chemical Process Unit 

Valves – Gas Serviceb 87 67 92 

Valves – Light Liquid Servicec 84 61 88 

Pumps – Light Liquid Servicec 69 45 75 

Connectors – All Services 93 

Refi nery 

Valves – Gas Serviceb 88 70 96 

Valves – Light Liquid Servicec 76 61 95 

Pumps – Light Liquid Servicec 68 45 88 

Connectors – All Services 81 

Source: Protocol for Equipment Leak Emission Estimates, EPA-453/R-95-017, Nov 1995. 

a Control effectiveness attributable to the HON-negotiated equipment leak regulation (40 CFR 63, Subpart H) is estimated based on equipment-specific leak 

definitions and performance levels. However, pumps subject to the HON at existing process units have a 1,000 to 5,000 ppm leak definition, depending on the 

type of process. b Gas (vapor) service means the material in contact with the equipment component is in a gaseous state at the process operating conditions. c Light liquid service means the material in contact with the equipment component is in a liquid state in which the sum of the concentration of individual constituents with a vapor pressure above 0.3 kilopascals (kPa) at 20°C is greater than or equal to 20% by weight. 

7

Leak Detection and Repair—A Best Practices Guide


4.1 	 Reducing Product Losses 

In the petrochemical industry, saleable products 

are lost whenever emissions escape from process 

equipment. Lost product generally translates into 

lost revenue. 

4.2 	 Increasing Safety for Facility Workers and 

Operators 

Many of the compounds emitted from refi neries 

and chemical facilities may pose a hazard to exposed workers and operators. Reducing emissions 

from leaking equipment has the direct benefi t of 

reducing occupational exposure to hazardous compounds. 

4.3 	 Decreasing Exposure for the Surrounding 

Community 

In addition to workers and operators at a facility, the population of a surrounding community 

can be affected by severe, long-term exposure to 

toxic air pollutants as a result of leaking equipment. Although most of the community exposure 

may be episodic, chronic health effects can result 

from long-term exposure to emissions from leaking 

equipment that is either not identified as leaking or 

not repaired. 

4.4 	 Potentially Reducing Emission Fees 

To fund permitting programs, some states and local 

air pollution districts charge annual fees that are 

based on total facility emissions. A facility with an 

effective program for reducing leaking equipment 

can potentially decrease the amount of these annual fees. 

4.5 	 Avoiding Enforcement Actions 

In setting Compliance and Enforcement National 

Priorities for Air Toxics, EPA has identifi ed LDAR 

programs as a national focus. Th erefore, facilities 

can expect an increased number and frequency of 

compliance inspections and a closer review of compliance reports submitted to permitting authorities 

in an effort by the Agency to assess LDAR programs 

and identify potential LDAR problems. A facility with an effective LDAR program decreases the 

chances of being targeted for enforcement actions 

and avoids the costs and penalties associated with 

rule violations. 

Example – Cost of product lost. 

In previous rulemaking efforts, EPA has esti­


mated that the average value of product lost 


due to equipment leaks is $1,370 per ton.a


Applying this cost factor results in a potential 


savings of $730,000 per year per facility.


a 	 Source: Hazardous Air Pollutant Emissions From 


Process Units in the Synthetic Organic Chemical 


Manufacturing Industry-Background Information 


for Proposed Standards, Vol. 1C-Model Emission 


Sources. Emission Standards Division, US EPA, 


Office of Air and Radiation, OAQPS, Research 


Triangle Park, NC. Nov 1992.


8

Leak Detection and Repair—A Best Practices Guide


5.0 Elements of an LDAR Program


The requirements among the regulations vary, For each element, this section outlines the typical 

but all LDAR programs consist of five basic ele- LDAR program requirements, common compliance 

ments, which are discussed in detail in Sections 5.1 problems found through field inspections, and a 

through 5.5. set of best practices used by facilities with eff ective 

LDAR programs. 

Identifying Components 

Leak Definition


Monitoring Components 

Repairing Components 

Recordkeeping


9

Leak Detection and Repair—A Best Practices Guide


Current Requirements 

• 	Assign a unique identification (ID) number to each regulated component. 

• 	Record each regulated component and its unique ID number in a 

log. 

• 	Physically locate each regulated component in the facility, verify its 

location on the piping and instrumentation diagrams (P&IDs) or process flow diagrams, and update the log if necessary. Some states 

require a physical tag on each component subject to the LDAR 

requirements. 

Leak Definition • 	Identify each regulated component on a site plot plan or on a continuously updated equipment log. 

• 	Promptly note in the equipment log when new and replacement 

pieces of equipment are added and equipment is taken out of service. 

Monitoring Components Common Problems 

• 	Not properly identifying all regulated equipment components. 

• 	Not properly documenting exempt components (e.g., <300 hour 

exemption and <5 (or <10) weight % HAP). 

Repairing Components Best Practices 

• 	Physically tag each regulated equipment component with a unique 

ID number. 

• 	Write the component ID number on piping and instrumentation 

diagrams. 

• 	Institute an electronic data management system for LDAR data and 

records, possibly including the use of bar coding equipment. 

• 	Periodically perform a field audit to ensure lists and diagrams accurately represent equipment installed in the plant. 

Identifying Components 

Recordkeeping 

10

Leak Detection and Repair—A Best Practices Guide


Current Requirements 

• 	Method 21 requires VOC emissions from regulated components to 

be measured in parts per million (ppm). A leak is detected whenever the measured concentration exceeds the threshold standard 

(i.e., leak definition) for the applicable regulation. 

– 	Leak definitions vary by regulation, component type, service (e.g., 

light liquid, heavy liquid, gas/vapor), and monitoring interval. 

– 	Most NSPS have a leak definition of 10,000 ppm. Many NESHAP 

use a 500-ppm or 1,000-ppm leak definition. 

Leak Definition • Many equipment leak regulations also define a leak based on visual 

inspections and observations (such as fluids dripping, spraying, 

misting or clouding from or around components), sound (such as 

hissing), and smell. 

Note: The LDAR requirements specify weekly visual inspections of 

Monitoring Components pumps, agitators, and compressors for indications of liquids 

leaking from the seals. 

Identifying Components 

Repairing Components 

Common Problems 

• 	Using the wrong leak definition for a particular component due to 

confusion at facilities where multiple LDAR regulations apply. 

Best Practices 

• 	Utilize a leak definition lower than what the regulation requires. 

• 	Simplify the program by using the lowest leak definition when multiple leak definitions exist. Recordkeeping 

• 	Make the lowest leak definition conservative to provide a margin of 

safety when monitoring components. 

• 	Keep the lowest leak definition consistent among all similar component types. For example, all valves in a facility might have a leak 

definition of 500 ppm. 

11

Leak Detection and Repair—A Best Practices Guide


Identifying Components 

Leak Definition 

Monitoring Components 

Repairing Components 

Recordkeeping 

The monitoring interval is the frequency at 

which individual component monitoring is conducted. 

For example, valves are generally 

required to be monitored once a 

month using a leak detection instrument, but the monitoring interval may be extended (e.g. to once 

every quarter for each valve that 

has not leaked for two successive 

months for Part 60 Subpart VV, 

or on a process unit basis of once 

every quarter for process units 

that have less than a 2% leak rate 

for Part 63 Subpart H). 

Current Requirements 

• 	For many NSPS and NESHAP regulations with leak detection provisions, 

the primary method for monitoring to detect leaking components is EPA 

Reference Method 21 (40 CFR Part 60, Appendix A). 

• 	Method 21 is a procedure used to detect VOC leaks from process equipment using a portable detecting instrument. 

• 	Appendix C of this guide explains the general procedure and Appendix D 

presents the complete Method 21 requirements. 

• 	Monitoring intervals vary according to the applicable regulation, but are typically weekly, monthly, quarterly, and yearly. For connectors, the monitoring 

interval can be every 2, 4, or 8 years. The monitoring interval depends on 

the component type and periodic leak rate for the component type. 

Common Problems 

• 	Not following Method 21 properly. 

• 	Failing to monitor at the maximum leak location (once the highest reading is obtained by placing the probe on and around the interface, hold the 

probe at that location approximately two times the response rate of the 

instrument). 

• 	Not monitoring long enough to identify a leak. 

• 	Holding the detection probe too far away from the component interface. 

The reading must be taken at the interface. 

• 	Not monitoring all potential leak interfaces. 

• 	Using an incorrect or an expired calibration gas. 

• 	Not monitoring all regulated components. 

• 	Not completing monitoring if the first monitoring attempt is unsuccessful 

due to equipment being temporarily out of service. 

Best Practices 

• 	Although not required by Method 21, use an automatic (electronic) data 

logger to save time, improve accuracy, and provide an audit record. 

• 	Audit the LDAR program to help ensure that the correct equipment is being 

monitored, Method 21 procedures are being followed properly, and the 

required records are being kept. 

• 	Monitor components more frequently than required by the regulations. 

• 	Perform QA/QC of LDAR data to ensure accuracy, completeness, and to 

check for inconsistencies. 

• 	Eliminate any obstructions (e.g., grease on the component interface) that 

would prevent monitoring at the interface. 

• 	If a rule allows the use of alternatives to Method 21 monitoring, Method 

21 should still be used periodically to check the results of the alternative 

monitoring method. 

12

Leak Detection and Repair—A Best Practices Guide


Identifying Components 

Leak Definition 

Monitoring Components 

Repairing Components 

Recordkeeping 

Current Requirements 

• 	Repair leaking components as soon as practicable, but not later than a 

specified number of calendar days (usually 5 days for a first attempt at 

repair and 15 days for final attempt at repair) after the leak is detected. 

• 	First attempts at repair include, but are not limited to, the following 

practices where practicable and appropriate: 

• 	Tightening bonnet bolts 

• 	Replacing bonnet bolts 

• 	Tightening packing gland nuts 

• 	Injecting lubricant into lubricated packing 

• 	If the repair of any component is technically infeasible without a process 

unit shutdown, the component may be placed on the Delay of Repair 

list, the ID number is recorded, and an explanation of why the component cannot be repaired immediately is provided. An estimated date for 

repairing the component must be included in the facility records. 

Note: 	The “drill and tap” method for repairing leaking valves is generally considered technically feasible without requiring a process 

unit shutdown and should be tried if the first attempt at repair 

does not fix the leaking valve. See section 6.7 for a discussion of 

“drill and tap”. 

• 	The component is considered to be repaired only after it has been 

monitored and shown not to be leaking above the applicable leak definition. 

Common Problems 

• 	Not repairing leaking equipment within the required amount of time 

specified by the applicable regulation. 

• 	Improperly placing components on the Delay of Repair list. 

• 	Not having a justifiable reason for why it is technically infeasible to 

repair the component without a process unit shutdown. 

• 	Not exploring all available repair alternatives before exercising the Delay 

of Repair exemption (specifically as it pertains to valves and “drill and 

tap” repairs). 

Best Practices 

• 	Develop a plan and timetable for repairing components. 

• 	Make a first attempt at repair as soon as possible after a leak is detected. 

• 	Monitor components daily and over several days to ensure a leak has 

been successfully repaired. 

• 	Replace problem components with “leakless” or other technologies. 

13

Leak Detection and Repair—A Best Practices Guide


Identifying Components 

Leak Definit ion 

Monitoring Components 

Repairing Components 

Recordkeeping 

Current Requirements 

For each regulated process: 

• 	Maintain a list of all ID numbers for all equipment subject to an 

equipment leak regulation. 

• 	For valves designated as “unsafe to monitor,” maintain a list of ID 

numbers and an explanation/review of conditions for the designation. 

• 	Maintain detailed schematics, equipment design specifications 

(including dates and descriptions of any changes), and piping and 

instrumentation diagrams. 

• 	Maintain the results of performance testing and leak detection 

monitoring, including leak monitoring results per the leak frequency, 

monitoring leakless equipment, and non-periodic event monitoring. 

For leaking equipment: 

• 	Attach ID tags to the equipment. 

• 	Maintain records of the equipment ID number, the instrument and 

operator ID numbers, and the date the leak was detected. 

• 	Maintain a list of the dates of each repair attempt and an explanation 

of the attempted repair method. 

• 	Note the dates of successful repairs. 

• 	Include the results of monitoring tests to determine if the repair was 

successful. 

Common Problems 

• 	Not keeping detailed and accurate records required by the applicable regulation. 

• 	Not updating records to designate new components that are subject 

to LDAR due to revised regulations or process modifications. 

Best Practices 

• 	Perform internal and third-party audits of LDAR records on a regular 

basis to ensure compliance. 

• 	Electronically monitor and store LDAR data including regular QA/QC 

audits. 

• 	Perform regular records maintenance. 

• 	Continually search for and update regulatory requirements. 

• 	Properly record and report first attempts at repair. 

• 	Keep the proper records for components on Delay of Repair lists. 

14

Leak Detection and Repair—A Best Practices Guide


6.0 What Compliance Problems Have Been Found With Current 


LDAR Programs? 

Many regulatory agencies determine the compliance status of LDAR programs based on a review of 

submitted paperwork. Some conduct walk-through 

inspections to review LDAR records maintained 

on site and perform a visual check of monitoring 

practices. However, a records review will not show 

if monitoring procedures are being followed. Similarly, the typical walkthrough inspection will not 

likely detect improper monitoring practices since 

operators will tend to ensure that they are following 

proper procedures when they are being watched. 

EPA’s National Enforcement Investigations Center 

(NEIC) conducted a number of sampling investigations of LDAR programs at 17 petroleum refi neries. 

Appendix E summarizes the comparative monitoring results, and Appendix F contains a copy of the 

1999 Enforcement Alert that explains the monitoring results. The investigations consisted of records 

review and comparative leak monitoring (comparing the leak rate found by NEIC to the facility’s 

historic leak rate) at a subset of the facility’s total 

components. These investigations have shown 

a pattern of significantly higher equipment leak 

rates (5%) than what the refineries reported (1.3%). 

While there have been improvements since 1999, 

facility audits are still showing signifi cantly elevated leak rates, especially in the chemical manufacturing industries. 

The discrepancy in leak rates indicates that monitoring staff may not be complying with Method 21 

procedures. Failure to accurately detect leaks may 

be due to a lack of internal quality control oversight 

or management accountability for the LDAR programs regardless of whether the monitoring is done 

by contractors or in-house personnel. 

Each leak that is not detected and repaired is a lost 

opportunity to reduce emissions. In the October 

1999 Enforcement Alert, EPA estimates that an additional 40,000 tons of VOCs are emitted annually 

from petroleum refineries because leaking valves 

are not found and repaired. 

Several important factors contribute to failing to 

identify and repair leaking components: 

1. Not identifying all regulated components/units in inventory 

If a facility does not properly identify all of its 

regulated components, some leaks may go 

unidentified. Unidentified components may 

leak or have existing leaks that will worsen 

over time if the components are not properly 

identified, monitored and repaired. Facilities can fail to identify regulated components 

when new processes are constructed, existing process are modified, or new or revised 

equipment leak regulations are published. 

2. Not monitoring components 

In some cases, the number of components reported to have been monitored may indicate 

problems with monitoring procedures. What 

facility inspectors have found: 

• 	 A data logger time stamp showed valves 

being monitored at the rate of one per 

second with two valves occasionally be15

Leak Detection and Repair—A Best Practices Guide


ing monitored within the same 1-second 

period. 

• 	 At one facility, a person reported monitoring 8,000 components in one day (assuming an 8-hour work day, that represents 

one component every 3.6 seconds). 

• 	 Records evaluations showed widely varying component monitoring counts, suggesting equipment might not always be 

monitored when required. 

• 	 Equipment was marked “temporarily out 

of service” because the initial inspection 

attempt could not be performed. However, the equipment was in service for most 

of the period, and no subsequent (or prior) 

inspection attempts were performed to 

meet the monitoring requirement. 

However, even when records show a realistic 

number of components are being monitored, 

if there are no oversight or accountability 

checks, then there is no guarantee that components are actually being monitored. 

A well-trained LDAR inspection 

team (two people) can monitor 

approximately 500-700 valves 

per day. 

3. Insufficient time to identify a leak 

In other cases, facilities are not following 

proper monitoring procedures, resulting in a 

lower number of leaking components being 

reported. 

• 	 If a worker moves the probe around the 

component interface so rapidly that the 

instrument does not have time to properly 

respond, then a component may never be 

identified as leaking. 

• 	 If a worker fails to find the maximum leak 

location for the component and then does 

not spend twice the response time at that 

location, then the monitoring instrument 

will not measure the correct concentration of hydrocarbons and the leak may 

go undetected. Optical leak imaging 

shows the importance of identifying the maximum leak location, as 

hydrocarbons are quickly dispersed 

and diluted by air currents around the 

component. 

4. Holding the probe away from the component interface 

The probe must be placed at the proper 

interface of the component being analyzed. 

Placing the probe even 1 centimeter from the 

interface can result in a false reading, indicating that the component is not leaking, when 

in fact it is leaking. Eliminate any issues (e.g., 

grease on the component interface) that prevent monitoring at the interface (e.g., remove 

excess grease from the component before 

monitoring or use a monitor that won’t be 

impacted by the grease and is easy to clean. 

16

A California Bay Area Air Quality 

Management District rule effectiveness 

study showed that if an operator 

measured 1 centimeter (0.4 inches) 

from the component leak interface, the 

operator would find only 79% of valves 

leaking between 100 ppm and 500 

ppm and only 43% of the valves leaking 

above 500 ppm.

Source: Draft Staff Report, Regulation 8, 

Rule 18, Equipment Leaks, Bay Area Air 

Quality Management District, Jul 1997.

Leak Detection and Repair—A Best Practices Guide


For equipment with rotating shafts (pumps 


and compressors), Method 21 requires the 


probe be placed within 1 centimeter of the 


Typical TVA (Toxic Vapor 

Analyzer) response times are 

around 2 – 4 seconds. 

shaft-seal interface. Placing the probe at the 

surface of the rotating shaft is a safety hazard 

and should be avoided. 

5. Failing to properly maintain monitoring 

instrument 

Factors that may prevent the instrument 

from identifying leaks are: 

• 	 Not using an instrument that meets the 

specifications required in Method 21, section 6. 

• 	 Dirty instrument probes; 

• 	 Leakage from the instrument probes; 

• 	 Not zeroing instrument meter; 

• 	 Incorrect calibration gases used; and 

• 	 Not calibrating the detection instrument 

on a daily basis. 

6. Improperly identifying components as 

“unsafe” or “diffi cult” to monitor 

Components that are identified as being 

“unsafe to monitor” or “diffi cult to monitor” 

must be identified as such because there is a 

safety concern or an accessibility issue that 

prevents the component from being successfully monitored. 

All unsafe or diffi cult-to-monitor components must be included on a log with identification numbers and an explanation of why 

the component is “unsafe to monitor” or “difficult to monitor.” Monitoring can be deferred 

for all such components, but the facility must 

maintain a plan that explains the conditions 

under which the components become safe to 

monitor or no longer difficult to monitor. 

17

Leak Detection and Repair—A Best Practices Guide 

7. Improperly placing components/units 

on the “Delay of Repair” list 

Generally, placing a leaking component on 

the “Delay of Repair” list is permissible only 

when the component is technically infeasible 

to repair without a process unit shutdown 

(e.g., for valves the owner/operator must 

demonstrate that the emissions from immediate repair will be greater than waiting for 

unit shutdown). 

Repair methods may exist, such as “drill and 

tap” for valves, that allow leaks to be fi xed 

while the component is still in service. Failing to consider such repair methods before 

exercising the “Delay of Repair” list may constitute noncompliance with repair requirements (usually 15 days under federal LDAR 

standards). 

Components placed on the “Delay of Repair” 

list must be accompanied by their ID numbers and an explanation of why they have 

been placed on the list. Th ese components 

cannot remain on the list indefinitely – they 

must be repaired by the end of the next process unit shutdown. 

Drill and Tap is a repair method where 

a hole is drilled into the valve packing gland and tapped, so that a small 

valve and fitting can be attached to the gland. 

A packing gun is connected to this fitting and 

the small valve is opened allowing new packing 

material to be pumped into the packing gland. 

Many companies consider this a permanent 

repair technique, as newer, pumpable packing 

types are frequently superior to the older packing types they replace. Packing types can be 

changed and optimized for the specific application over time. 

18

Leak Detection and Repair—A Best Practices Guide 

7.0 Model LDAR Program 

Experience has shown that facilities with an eff ective record of preventing leaks integrate an awareness of the benefits of leak detection and repair into 

their operating and maintenance program. Th is 

section outlines some of the major elements of successful LDAR programs. These program elements 

were developed from: 

• 	 Evaluation of best practices identifi ed at 

facilities with successful LDAR programs, and 

• 	 Analysis of the root causes of noncompliance 

at facilities that were found to have recurring 

violations of LDAR regulatory requirements. 

LDAR programs that incorporate most or all of the 

elements described in the following sections have 

achieved more consistent results in their LDAR 

programs, leading to increased compliance and 

lower emissions. 

Written LDAR Program 

(Section 7.1) 

Training 

(Section 7.2) 

QA/QC of LDAR Data 

(Section 7.10) 

Calibration/Calibration 

Drift Assessment 

(Section 7.11) 

Electronic Monitoring 

and Storage of Data 

(Section 7.9) 

First Attempt at Repair 

(Section 7.7) 

More Frequent Monitoring 

(Section 7.6) 

LDAR Audits 

(Section 7.3) 

Contractor Accountability 

(Section 7.4) 

Internal Leak Definitions 

(Section 7.5) 

Records Maintenance 

(Section 7.12) 

Delay of Repair Compliance Assurance 

(Section 7.8) 

Model

LDAR

Program

19

Leak Detection and Repair—A Best Practices Guide


7.1 Written LDAR Program 

A written LDAR program specifies the regulatory 

requirements and facility-specific procedures for recordkeeping certifications, monitoring, and repairs. 

A written program also delineates the roles of each 

person on the LDAR team as well as documents all 

the required procedures to be completed and data 

to be gathered, thus establishing accountability. 

The plan should identify all process units subject 

to federal, state, and local LDAR regulations and 

be updated as necessary to ensure accuracy and 

continuing compliance. 

Elements: 

• 	An overall, facility-wide leak rate goal that will be a 


target on a process-unit-by-process-unit basis;


• 	A list of all equipment in light liquid and/or in gas/


vapor service that has the potential to leak VOCs 


and VHAPs, within process units that are owned 


and maintained by each facility;


• 	Procedures for identifying leaking equipment 


within process units;


• 	Procedures for repairing and keeping track of leak­


ing equipment;


• 	A process for evaluating new and replacement 


equipment to promote the consideration of install­


ing equipment that will minimize leaks or eliminate 


chronic leakers;


• 	A list of “LDAR Personnel” and a description 


of their roles and responsibilities, including the 


person or position for each facility that has the 


authority to implement improvements to the LDAR 


program; and


• 	Procedures (e.g., a Management of Change pro­


gram) to ensure that components added to each 


facility during maintenance and construction are 


evaluated to determine if they are subject to LDAR 


requirements, and that affected components are 


integrated into the LDAR program.


Within thirty (30) days after developing the written facility-wide LDAR program, submit a copy of 

the Program to EPA and to the appropriate state 

agency. 

7.2 Training 

A training program will provide LDAR personnel 

the technical understanding to make the written 

LDAR program work. It also will educate members 

of the LDAR team on their individual responsibilities. These training programs can vary according to 

the level of involvement and degree of responsibility 

of LDAR personnel. 

Elements: 

• 	Provide and require initial training and annual 


LDAR refresher training for all facility employees 


assigned LDAR compliance responsibilities, such 


as monitoring technicians, database users, QA/QC 


personnel, and the LDAR Coordinator;


• 	For other operations and maintenance personnel 


with responsibilities related to LDAR, provide and 


require an initial training program that includes 


instruction on aspects of LDAR that are relevant to 


their duties (e.g., operators and mechanics per­


forming valve packing and unit supervisors that 


approve delay of repair work). Provide and require 


“refresher” training in LDAR for these personnel at 


least every three years.


• 	Collect training information and records of contrac­


tors, if used.


20

Leak Detection and Repair—A Best Practices Guide


7.3 LDAR Audits 

Whether LDAR monitoring is done in house or 

contracted to third parties outside the company, 

the potential exists for LDAR staff not to adhere 

correctly to the LDAR program. Internal and 

third-party audits of a facility LDAR program are 

a critical component of effective LDAR programs. 

The audits check that the correct equipment is 

being monitored, Method 21 procedures are being 

followed, leaks are being fixed, and the required 

records are being kept. In short, the audits ensure 

that the LDAR program is being conducted correctly and problems are identified and corrected. 

Elements: 

• 	Review records on a regular cycle to ensure that all 

required LDAR-related records, logs, and databases 

are being maintained and are up to date. 

• 	Ensure and document that the correct equipment is 

included in the LDAR program and that equipment 

identified as leaking is physically tagged with the 

equipment ID number. 

• 	Observe the calibration and monitoring techniques 

used by LDAR technicians, in particular to ensure 

the entire interface is checked and the probe is held 

at the interface, not away from the interface. 

• 	Retain a contractor to perform a third-party audit of 

the facility LDAR program at least once every four 

(4) years. 

• 	Perform facility-led audits every four (4) years. 

– 	Use personnel familiar with the LDAR program 

and its requirements from one or more of the 

company’s other facilities or locations (if available). 

– 	Perform the first round of facility-led LDAR audits 

no later than two (2) years after completion of the 

third-party audits outlined above, and every four 

(4) years thereafter. 

– 	This rotation ensures that the facility is being 


audited once every two (2) years.


• 	If areas of noncompliance are discovered, initiate a 

plan to resolve and document those issues. 

• 	Implement, as soon as practicable, steps necessary 

to correct causes of noncompliance, and prevent, to 

the extent practicable, a recurrence of the cause of 

the noncompliance. 

• 	Retain the audit reports and maintain a written 

record of the corrective actions taken in response to 

any deficiencies identified. 

21

7.4 	Contractor Accountability 

Contractors performing monitoring are frequently 

compensated for the number of components they 

monitor, which might provide an incentive to rush 

through monitoring procedures and not adhere to 

Method 21 requirements for response time, monitoring distance, etc. If this happens, some equipment leaks may not be detected. To overcome this 

potential problem, facilities should have in place 

sufficient oversight procedures to increase the accountability of contractors. 

Elements: 

• 	Write contracts that emphasize the quality of 


work instead of the quantity of work only.


• 	Require contractors to submit documentation 


that their LDAR personnel have been trained on 


Method 21 and facility-specific LDAR proce­


dures.


• 	Ensure that the contractor has a procedure in 


place to review and certify the monitoring data 


before submitting the data to the facility.


• 	Review daily results of contractor work to en­


sure that a realistic number of components are 


being monitored.


• 	Perform spot audits in the field to ensure that 


Method 21 procedures are being followed. 


This can include spot-checking monitored 


components with another hydrocarbon analyzer 


or following LDAR personnel as they perform 


monitoring.


• 	Have periodic reviews of contractor perfor­


mance (e.g., quarterly or semi-annually) to 


resolve issues and correct problems.


Leak Detection and Repair—A Best Practices Guide 

7.5 	 Internal Leak Definition for Valves and 

Pumps 

The varying leak definitions that can apply to 

different process units and components can be 

confusing and lead to errors in properly identifying 

leaks. To counter this potential problem, operate 

your LDAR program using an internal leak defi nition for valves and pumps in light liquid or gas 

vapor service. The internal leak definition would be 

equivalent to or lower than the applicable defi nitions in your permit and the applicable federal, 

state, and local regulations. Monitoring against a 

uniform definition that is lower than the applicable 

regulatory definition will reduce errors and provide 

a margin of safety for identifying leaking components. The internal leak definition would apply to 

valves and pumps (and possibly connectors) in light 

liquid or gas vapor service. 

Elements: 

• 	Adopt a 500-ppm or lower internal leak definition 

for VOCs for all valves in light liquid and/or gas 

vapor service, excluding pressure relief devices. 

• 	Adopt a 2,000-ppm or lower internal leak definition 

for pumps in light liquid and/or gas/vapor service. 

• 	Record, track, repair, and monitor leaks in excess 

of the internal leak definition. Repair and monitor 

leaks that are greater than the internal leak definitions but less than the applicable regulatory leak 

definitions within thirty (30) days of detection. 

Consent Decrees between EPA and many chemical 

facilities subject to the HON require using a 250-ppm 

leak definition for valves and connectors and a 500­

ppm leak definition for pumps. 

Note: 	If a state or local agency has lower leak definitions, then the internal leak definition should 

be set to the lowest definition or even lower to 

include/allow for margin of error. 

22

Leak Detection and Repair—A Best Practices Guide 

7.6 More Frequent Monitoring 

Many regulations allow for less frequent monitoring (i.e. skip periods) when good performance (as 

defined in the applicable regulation) is demonstrated. Skip period is an alternative work practice 

found in some equipment leak regulations and 

usually applies only to valves and connectors. After 

a specified number of leak detection periods (e.g., 

monthly) during which the percentage of leaking 

components is below a certain value (e.g., 2% for 

NSPS facilities), a facility can monitor less frequently (e.g., quarterly) as long as the percentage 

of leaking components remains low. Th e facility 

must keep a record of the percentage of the component type found leaking during each leak detection 

period. 

Experience has shown that poor monitoring rather 

than good performance has allowed facilities to 

take advantage of the less frequent monitoring 

provisions. To ensure that leaks are still being 

identified in a timely manner and that previously 

unidentified leaks are not worsening over time, 

implement a plan for more frequent monitoring for 

components that contribute most to equipment 

leak emissions. 

Elements: 

• 	Monitor pumps in light liquid and/or gas vapor 


service on a monthly basis.


• 	Monitor valves in light liquid and/or gas vapor 

service – other than difficult-to-monitor or unsafeto-monitor valves – with no skip periods. 

Consent Decrees between EPA and many chemical facilities subject to the HON require semiannual 

monitoring of connectors. 

7.7 Repairing Leaking Components 

To stop detected leaks while they are still small, 

most rules require a first attempt at repair within 5 

days of the leak detection and a final repair within 

15 days. However, any component that cannot be 

repaired within those time frames must be placed 

on a “Delay of Repair” list to be repaired during the 

next shutdown cycle. 

First attempts at repair include, but are not limited 

to, the following best practices where practicable 

and appropriate: 

• Tightening bonnet bolts; 

• Replacing bonnet bolts; 

• Tightening packing gland nuts; and 

• Injecting lubricant into lubricated packing. 

Elements: 

• 	Schedule the “first attempt at repair” of those 

components that the monitoring personnel are not 

authorized to repair consistent with the existing 

regulatory requirements. 

• 	Monitor the component for which a “first attempt 

at repair” was performed no later than the next 

regular business day to ensure the leak has not 

worsened. 

• 	If the first attempt at repair has not succeeded then 

other methods, such as “drill and tap” should be 

employed where feasible. Drill and tap procedures 

are no longer considered extraordinary practices. 

23

7.8 	 Delay of Repair Compliance Assurance 

Any component that cannot be repaired during the 

specified repair interval must be placed on a “Delay 

of Repair” list to be repaired during the next shutdown cycle. Delay of repair compliance assurance 

procedures ensure that the appropriate equipment 

is justifiably on the “Delay of Repair” list and that 

facilities have a plan to fix these components. 

Elements: 

• 	Have the unit supervisor approve in advance 


and certify all components that are technically 


infeasible to repair without a process unit shut­


down.


• 	Continue to monitor equipment that is placed on 

the “Delay of Repair” list in the facility’s regular 

LDAR monitoring. For leaks above the internal 

leak definition rate and below the regulatory 

rate, put the equipment on the “Delay of Repair” 

list within 30 days. 

• 	Implement the following repair policies and 


procedures within 15 days of implementing the 


written LDAR program:


– 	For valves, other than control valves or pressure relief valves, that are leaking at a rate of 

10,000 ppm or greater and cannot be feasibly 

repaired without a process unit shutdown, 

use “drill and tap” repair methods to fix the 

leaking valve, unless you can determine and 

document that there is a safety, mechanical, 

or major environmental concern posed by 

repairing the leak in this manner. 

– 	Perform up to two “drill and tap” repair attempts to repair a leaking valve, if necessary, 

within 30 days of identifying the leak. 

Leak Detection and Repair—A Best Practices Guide 

7.9 	 Electronic Monitoring and Storage of LDAR 

Data 

Electronic monitoring and storage of LDAR data 

will help evaluate the performance of monitoring personnel (via time/date stamps), improve 

accuracy, provide an effective means for QA/QC, 

and retrieve records in a timely manner for review 

purposes. Incorporate and maintain an electronic 

database for storing and reporting LDAR data. Use 

data loggers or other data collection devices during 

all LDAR monitoring. 

Elements: 

• 	Use best efforts to transfer, on a daily basis, electronic data from electronic data logging devices to 

the database. 

• 	For all monitoring events in which an electronic 

data collection device is used, include a time and 

date stamp, operator identification, and instrument 

identifi cation. 

• 	Paper logs can be used where necessary or more 

feasible (e.g., small rounds, re-monitoring fixed 

leaks, or when data loggers are not available 

or broken), and should record, at a minimum, 

the monitoring technician, date, and monitoring 

equipment used. 

• 	Transfer any manually recorded monitoring data to 

the database within 7 days of monitoring. 

• 	Review records to identify “problem” components 

for preventative maintenance (repair prior to anticipated failure) or for replacement with “leakless” 

technology. 

24

Leak Detection and Repair—A Best Practices Guide 

7.10 QA/QC of LDAR Data 

QA/QC audits ensure that Method 21 procedures 

are being followed and LDAR personnel are monitoring the correct components in the proper manner. Develop and implement a procedure to ensure 

QA/QC review of all data generated by LDAR 

monitoring technicians on a daily basis or at the 

conclusion of each monitoring episode. 

Elements: 

Some QA/QC procedures include: 

• 	Daily review/sign-off by monitoring technicians 


of the data they collected to ensure accuracy 


and validity.


• 	Periodic review of the daily monitoring reports 


generated in conjunction with recordkeeping 


and reporting requirements.


• 	Quarterly QA/QC of the facility’s and contractor’s


monitoring data including:


– 	Number of components monitored per technician; 

– 	Time between monitoring events; and 

– 	Abnormal data patterns. 

7.11 Calibration/Calibration Drift Assessment 

Always calibrate LDAR monitoring equipment using an appropriate calibration gas, in accordance 

with 40 CFR Part 60, EPA Reference Test Method 

21. 

Elements: 

• 	Conduct calibration drift assessments of LDAR 

monitoring equipment at the end of each monitoring shift, at a minimum. 

• 	Conduct the calibration drift assessment using, at 

a minimum, approximately 500 ppm of calibration gas. 

• 	If any calibration drift assessment after the initial 

calibration shows a negative drift of more than 

10% from the previous calibration, re-monitor all 

valves that were monitored since the last calibration with a reading of greater than 100 ppm. 

Re-monitor all pumps that were monitored since 

the last calibration with a reading of greater than 

500 ppm. 

25

Leak Detection and Repair—A Best Practices Guide 

7.12 Records Maintenance 

Organized and readily available records are one 

potential indication of an effective LDAR program. 

Well-kept records may also indicate that the LDAR 

program is integrated into the facility’s routine 

operation and management. The equipment leak 

regulations specify recordkeeping and reporting 

requirements; incorporating the elements below 

will help ensure your facility LDAR records are 

thorough and complete. 

Elements: (4) The number of valves and pumps found 

leaking; Records to maintain: 

(5) The number of “difficult to monitor” pieces • A certification that the facility implemented the of equipment monitored; “first attempt at repair” program. 

(6) A list of all equipment currently on the • A certification that the facility implemented “Delay of Repair” list and the date each QA/QC procedures for review of data generated component was placed on the list; by LDAR technicians. 

(7) The number of repair attempts not com­ • An identification of the person/position at each pleted promptly or completed within 5 facility responsible for LDAR program perfor­ days; mance as defined in the written program. 

(8) The number of repairs not completed • A certification that the facility developed and within 30 days and the number of compo- implemented a tracking program for new nents not placed on the “Delay of Repair” valves and pumps added during maintenance list; and and construction defined in the written pro­

(9) The number of chronic leakers that do not gram.


get repaired.
 • A certification that the facility properly completed calibration drift assessments.	 • Records of audits and corrective actions. Prior 

to the first third-party audit at each facility, • A certification that the facility implemented the include in your records a copy of each audit “delay of repair” procedures. report from audits conducted in the previous 

• The following information on LDAR monitoring: calendar year and a summary of the actions 

(1) The number of valves and pumps present 	 planned or taken to correct all deficiencies 

in each process unit during the quarter; identified in the audits. 

(2) The number of valves and pumps moni-	 • For the audits performed in prior years, identored in each process unit; tification of the auditors and documentation 

(3) An explanation for missed monitoring if 	 that a written plan exists identifying corrective 

the number of valves and pumps present action for any deficiencies identified and that 

exceeds the number of valves and pumps this plan is being implemented.


monitored during the quarter;


26

Leak Detection and Repair—A Best Practices Guide 

8.0 Sources of Additional Information 

Inspection Manual: Federal Equipment Leak Regulations for the Chemical Manufacturing Industry, 

EPA/305/B-98/011, December 1998. 

http://cfpub.epa.gov/compliance/resources/publications/assistance/sectors/chemical/index.cfm 

Vol 1: Inspection Manual 

http://www.epa.gov/compliance/resources/publications/assistance/sectors/insmanvol1.pdf 

Vol 2: Chemical Manufacturing Industry Regulations (3 parts on the Internet) 

http://www.epa.gov/compliance/resources/publications/assistance/sectors/insmanvol2pt1.pdf 

http://www.epa.gov/compliance/resources/publications/assistance/sectors/insmanvol2pt2.pdf 

http://www.epa.gov/compliance/resources/publications/assistance/sectors/insmanvol2pt3.pdf 

Vol 3: Petroleum Refining Industry Regulations 

http://www.epa.gov/compliance/resources/publications/assistance/sectors/insmanvol3.pdf 

1995 Protocol for Equipment Leak Emission Estimates, EPA-453/R-95-017, Nov 1995.


http://www.epa.gov/ttnchie1/efdocs/equiplks.pdf


Enforcement Alert, EPA Office of Enforcement and Compliance Assurance, 


EPA 300-N-99-014, Oct 1999.


http://www.epa.gov/compliance/resources/newsletters/civil/enfalert/emissions.pdf


National Petroleum Refinery Initiative, EPA.


http://www.epa.gov/compliance/resources/cases/civil/caa/refi neryinitiative032106.pdf


Petroleum Refinery Initiative Fact Sheet, EPA.


http://www.epa.gov/compliance/resources/cases/civil/caa/petroleumrefi nery-fcsht.html


Petroleum Refinery National Priority Case Results.


http://www.epa.gov/compliance/resources/cases/civil/caa/oil/


Draft Staff Report, Regulation 8, Rule 18, Equipment Leaks, Bay Area Air Quality Management District, 


Jul 1997.


http://www.baaqmd.gov/pln/ruledev/8-18/1997/0818_sr_071097.pdf


Standards of Performance for Equipment Leaks of VOC in the Synthetic Organic Chemicals Manu­


facturing Industry; Standards of Performance for Equipment Leaks of VOC in Petroleum Refi neries; 


Proposed Rule, [EPA-HQ-OAR-2006-0699; FRL- ] RIN 2060-AN71.


http://www.epa.gov/ttn/oarpg/t3/fr_notices/equip_leak_prop103106.pdf


Industrial Organic Chemicals Compliance Incentive Program, EPA Compliance and Enforcement.


http://www.epa.gov/compliance/incentives/programs/ioccip.html


27

Leak Detection and Repair—A Best Practices Guide 

Leak Detection and Repair Program Developments. 


http://www.epa.gov/compliance/neic/fi eld/leak.html


Compliance and Enforcement Annual Results: Important Environmental Problems / National Priorities.


http://www.epa.gov/compliance/resources/reports/endofyear/eoy2006/sp-airtoxics-natl-priorities.html


Portable Instruments User’s Manual For Monitoring VOC Sources, EPA-340/1-86-015.


Inspection Techniques For Fugitive VOC Emission Sources, EPA 340/1-90-026a,d,e,f (rev May 1993) Course #380.


Environmental compliance assistance resources can be found at: 

http://cfpub.epa.gov/clearinghouse/


http://www.assistancecenters.net/


http://www.epa.gov/compliance/assistance/sectors/index.html


28

Leak Detection and Repair—A Best Practices Guide 

Appendix A 	 Federal Regulations That Require a Formal LDAR 

Program With Method 21 

Part 

40 CFR 

Subpart Regulation Title 

60 VV SOCMI VOC Equipment Leaks NSPS 

60 DDD Volatile Organic Compound (VOC) Emissions from the Polymer Manufacturing 

Industry 

60 GGG Petroleum Refinery VOC Equipment Leaks NSPS 

60 KKK Onshore Natural Gas Processing Plant VOC Equipment Leaks NSPS 

61 J National Emission Standard for Equipment Leaks (Fugitive Emission Sources) of 

Benzene 

61 V Equipment Leaks NESHAP 

63 H Organic HAP Equipment Leak NESHAP (HON) 

63 I Organic HAP Equipment Leak NESHAP for Certain Processes 

63 J Polyvinyl Chloride and Copolymers Production NESHAP 

63 R Gasoline Distribution Facilities (Bulk Gasoline Terminals and Pipeline Breakout 

Stations) 

63 CC Hazardous Air Pollutants from Petroleum Refi neries 

63 DD Hazardous Air Pollutants from Off-Site Waste and Recovery Operations 

63 SS Closed Vent Systems, Control Devices, Recovery Devices and Routing to a Fuel 

Gas System or a Process 

63 TT Equipment Leaks – Control Level 1 

63 UU Equipment Leaks – Control Level 2 

63 YY Hazardous Air Pollutants for Source Categories: Generic Maximum Achievable 

Control Technology Standards 

63 GGG Pharmaceuticals Production 

63 III Hazardous Air Pollutants from Flexible Polyurethane Foam Production 

63 MMM Hazardous Air Pollutants for Pesticide Active Ingredient Production 

63 FFFF Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing 

63 GGGGG Hazardous Air Pollutants: Site Remediation 

63 HHHHH Hazardous Air Pollutants: Miscellaneous Coating Manufacturing 

65 F Consolidated Federal Air Rule – Equipment Leaks 

264 BB Equipment Leaks for Hazardous Waste TSDFs 

265 BB Equipment Leaks for Interim Status Hazardous Waste TSDFs 

Note: Many of these regulations have identical requirements, but some have different applicability 

and control requirements. 

29 
Leak Detection and Repair—A Best Practices Guide 

Appendix B 	 Federal Regulations That Require the Use 

of Method 21 But Do Not Require a Formal 

LDAR Program 

40 CFR 

Regulation Title 

Part Subpart 

60 XX Bulk Gasoline Terminals 

60 QQQ VOC Emissions from Petroleum Refinery Wastewater Systems 

60 WWW Municipal Solid Waste Landfi lls 

61 F Vinyl Chloride 

61 L Benzene from Coke By-Products 

61 BB Benzene Transfer 

61 FF Benzene Waste Operations 

63 G Organic Hazardous Air Pollutants from SOCMI for Process Vents, Storage 

Vessels, Transfer Operations, and Wastewater 

63 M Perchloroethylene Standards for Dry Cleaning 

63 S Hazardous Air Pollutants from the Pulp and Paper Industry 

63 Y Marine Unloading Operations 

63 EE Magnetic Tape Manufacturing Operations 

63 GG Aerospace Manufacturing and Rework Facilities 

63 HH Hazardous Air Pollutants from Oil and Gas Production Facilities 

63 OO Tanks – Level 1 

63 PP Containers 

63 QQ Surface Impoundments 

63 VV Oil/Water, Organic/Water Separators 

63 HHH Hazardous Air Pollutants from Natural Gas Transmission and Storage 

63 JJJ Hazardous Air Pollutant Emissions: Group IV Polymers and Resins 

63 VVV Hazardous Air Pollutants: Publicly Owned Treatment Works 

65 G CFAR – Closed Vent Systems 

264 AA Owners and Operators of Hazardous Waste Treatment, Storage, and Disposal 

Facilities - Process Vents 

264 CC Owners and Operators of Hazardous Waste Treatment, Storage and Disposal 

Facilities - Tanks, Surface Impoundments, Containers 

265 AA Interim Standards for Owners and Operators of Hazardous Waste Treatment, 

Storage, and Disposal Facilities – Process Vents 

265 CC Interim Standards for Owners and Operators of Hazardous Waste Treatment, 

Storage, and Disposal Facilities - Tanks, Surface Impoundments, Containers 

270 B Hazardous Waste Permit Program – Permit Application 

270 J Hazardous Waste Permit Program – RCRA Standardized Permits for Storage 

Tanks and Treatment Units 

30

Leak Detection and Repair—A Best Practices Guide 

Appendix C Method 21 General Procedure


Failure of facilities to follow Method 21 can 

lead to them not properly identifying and subsequently repairing leaking components. It is 

critical for facilities to refer to the complete 

text of Method 21 (see Appendix D) for detailed explanations of each general procedure 

found below and how to properly perform 

each step. 

1. Evaluate Instrument Performance 

Performance criteria for the monitoring 

instrument: 

• 	 For each VOC measured, the response factor should be <10 unless 

specified in the applicable regulation. Response factor is the ratio of 

the known concentration of a VOC 

compound to the observed meter 

reading when measured using an 

instrument calibrated with the 

reference compound specified in the 

applicable regulation. 

• 	The calibration precision should be 

<10 percent of the calibration gas 

value. Calibration precision is the 

degree of agreement between measurements of the same known value, 

expressed as the relative percentage 

of the average diff erence between 

the meter readings and the known 

concentration to the known concentration. 

• 	The response time should be ≤30 

seconds. Response time is the 

time interval from a step change 

in VOC concentration at the input 

of the sampling system to the time 

at which 90% of the corresponding 

final value is reached as displayed on 

the instrument readout meter. 

2. Calibrate Instrument 

Before each monitoring episode: 

• 	 Let the instrument warm up. 

• 	 Introduce the calibration gas into 

the instrument probe. 

• 	 Adjust the instrument meter readout to match the calibration gas concentration value. 

3. Monitor Individual components 

When monitoring components: 

• 	 Place the probe at the surface of the 

component interface where leakage 

could occur. 

• 	 Move the probe along the interface 

periphery while observing the instrument readout. 

• 	 Locate the maximum reading by 

moving the probe around the interface. 

• 	 Keep the probe at the location of the 

maximum reading for 2 times the 

response factor. 

• 	 If the concentration reading on the 

instrument readout is above the 

applicable leak definition, then the 

component is leaking and must be 

repaired. 

31

Leak Detection and Repair—A Best Practices Guide 

Appendix D 	 Method 21—Determination of Volatile Organic 

Compound Leaks 

1.0 Scope and Application 

1.1 Analytes. 

Analyte CAS No. 

Volatile Organic Compounds (VOC).......... No CAS number assigned. 

1.2 Scope. This method is applicable for the 

determination of VOC leaks from process 

equipment. These sources include, but are not 

limited to, valves, flanges and other connections, pumps and compressors, pressure relief 

devices, process drains, open-ended valves, 

pump and compressor seal system degassing vents, accumulator vessel vents, agitator 

seals, and access door seals. 

1.3 Data Quality Objectives. Adherence to the 

requirements of this method will enhance the 

quality of the data obtained from air pollutant 

sampling methods. 

2.0 Summary of Method 

2.1 A portable instrument is used to detect 

VOC leaks from individual sources. Th e 

instrument detector type is not specifi ed, but 

it must meet the specifications and performance criteria contained in Section 6.0. A 

leak definition concentration based on a 

reference compound is specified in each applicable regulation. This method is intended 

to locate and classify leaks only, and is not to 

be used as a direct measure of mass emission 

rate from individual sources. 

3.0 Defi nitions 

3.1 Calibration gas means the VOC compound used to adjust the instrument meter 

reading to a known value. The calibration gas 

is usually the reference compound at a known 

concentration approximately equal to the 

leak defi nition concentration. 

3.2 Calibration precision means the degree 

of agreement between measurements of the 

same known value, expressed as the relative 

percentage of the average diff erence between 

the meter readings and the known concentration to the known concentration. 

3.3 Leak definition concentration means the 

local VOC concentration at the surface of a 

leak source that indicates that a VOC emission (leak) is present. The leak definition is an 

instrument meter reading based on a reference compound. 

3.4 No detectable emission means a local VOC concentration at the surface of a 

leak source, adjusted for local VOC ambient 

concentration, that is less than 2.5 % of the 

specified leak definition concentration. Th at 

indicates that a VOC emission (leak) is not 

present. 

32

Leak Detection and Repair—A Best Practices Guide 

3.5 Reference compound means the VOC species 

selected as the instrument calibration basis for 

specification of the leak defi nition concentration. 

(For example, if a leak definition concentration is 

10,000 ppm as methane, then any source emission 

that results in a local concentration that yields a 

meter reading of 10,000 on an instrument meter 

calibrated with methane would be classified as a 

leak. In this example, the leak defi nition concentration is 10,000 ppm and the reference compound is 

methane.) 

3.6 Response factor means the ratio of the known 

concentration of a VOC compound to the observed 

meter reading when measured using an instrument 

calibrated with the reference compound specifi ed 

in the applicable regulation. 

3.7 Response time means the time interval from a 

step change in VOC concentration at the input of 

the sampling system to the time at which 90 percent of the corresponding final value is reached as 

displayed on the instrument readout meter. 

4.0 Interferences [Reserved] 

5.0 Safety 

5.1 Disclaimer. This method may involve hazardous materials, operations, and equipment. Th is test 

method may not address all of the safety problems 

associated with its use. It is the responsibility of the 

user of this test method to establish appropriate 

safety and health practices and determine the applicability of regulatory limitations prior to performing this test method. 

5.2 Hazardous Pollutants. Several of the compounds, leaks of which may be determined by this 

method, may be irritating or corrosive to tissues 

(e.g., heptane) or may be toxic (e.g., benzene, methyl 

alcohol). Nearly all are fire hazards. Compounds in 

emissions should be determined through familiarity with the source. Appropriate precautions can 

be found in reference documents, such as reference 

No. 4 in Section 16.0. 

6.0 Equipment and Supplies 

A VOC monitoring instrument meeting the following specifications is required: 

6.1 The VOC instrument detector shall respond to 

the compounds being processed. Detector types 

that may meet this requirement include, but are 

not limited to, catalytic oxidation, fl ame ionization, 

infrared absorption, and photoionization. 

6.2 The instrument shall be capable of measuring 

the leak definition concentration specified in the 

regulation. 

6.3 The scale of the instrument meter shall be 

readable to ±2.5 % of the specified leak defi nition 

concentration. 

6.4 The instrument shall be equipped with an 

electrically driven pump to ensure that a sample 

is provided to the detector at a constant fl ow rate. 

The nominal sample flow rate, as measured at the 

sample probe tip, shall be 0.10 to 3.0 l/min (0.004 to 

0.1 ft 3 /min) when the probe is fitted with a glass 

wool plug or filter that may be used to prevent 

plugging of the instrument. 

6.5 The instrument shall be equipped with a probe 

or probe extension or sampling not to exceed 6.4 

mm ( 1/4 in) in outside diameter, with a single end 

opening for admission of sample. 

33

Leak Detection and Repair—A Best Practices Guide


6.6 The instrument shall be intrinsically safe for 

operation in explosive atmospheres as defined by the 

National Electrical Code by the National Fire Prevention Association or other applicable regulatory code 

for operation in any explosive atmospheres that may 

be encountered in its use. The instrument shall, at a 

minimum, be intrinsically safe for Class 1, Division 

1 conditions, and/or Class 2, Division 1 conditions, 

as appropriate, as defined by the example code. Th e 

instrument shall not be operated with any safety 

device, such as an exhaust flame arrestor, removed. 

7.0 Reagents and Standards 

7.1 Two gas mixtures are required for instrument 

calibration and performance evaluation: 

7.1.1 Zero Gas. Air, less than 10 parts per million by 

volume (ppmv) VOC. 

7.1.2 Calibration Gas. For each organic species that 

is to be measured during individual source surveys, 

obtain or prepare a known standard in air at a concentration approximately equal to the applicable 

leak defi nition specified in the regulation. 

7.2 Cylinder Gases. If cylinder calibration gas mixtures are used, they must be analyzed and certifi ed 

by the manufacturer to be within 2 % accuracy, and 

a shelf life must be specified. Cylinder standards 

must be either reanalyzed or replaced at the end of 

the specified shelf life. 

7.3 Prepared Gases. Calibration gases may be 

prepared by the user according to any accepted 

gaseous preparation procedure that will yield a 

mixture accurate to within 2 percent. Prepared 

standards must be replaced each day of use unless 

it is demonstrated that degradation does not occur 

during storage. 

7.4 Mixtures with non-Reference Compound Gases. 

Calibrations may be performed using a compound 

other than the reference compound. In this case, 

a conversion factor must be determined for the alternative compound such that the resulting meter 

readings during source surveys can be converted to 

reference compound results. 

8.0 	Sample Collection, Preservation, Storage, 

and Transport 

8.1 Instrument Performance Evaluation. Assemble 

and start up the instrument according to the manufacturer’s instructions for recommended warmup 

period and preliminary adjustments. 

8.1.1 Response Factor. A response factor must be 

determined for each compound that is to be measured, either by testing or from reference sources. 

The response factor tests are required before placing the analyzer into service, but do not have to be 

repeated at subsequent intervals. 

8.1.1.1 Calibrate the instrument with the reference 

compound as specified in the applicable regulation. Introduce the calibration gas mixture to the 

analyzer and record the observed meter reading. Introduce zero gas until a stable reading is obtained. 

Make a total of three measurements by alternating 

between the calibration gas and zero gas. Calculate 

the response factor for each repetition and the average response factor. 

8.1.1.2 The instrument response factors for each 

of the individual VOC to be measured shall be less 

than 10 unless otherwise specified in the applicable 

regulation. When no instrument is available that 

meets this specification when calibrated with the 

reference VOC specified in the applicable regula34

Leak Detection and Repair—A Best Practices Guide 

tion, the available instrument may be calibrated 

with one of the VOC to be measured, or any other 

VOC, so long as the instrument then has a response 

factor of less than 10 for each of the individual VOC 

to be measured. 

8.1.1.3 Alternatively, if response factors have been 

published for the compounds of interest for the 

instrument or detector type, the response factor 

determination is not required, and existing results 

may be referenced. Examples of published response 

factors for flame ionization and catalytic oxidation 

detectors are included in References 1–3 of Section 

17.0. 

8.1.2 Calibration Precision. The calibration precision test must be completed prior to placing the 

analyzer into service and at subsequent 3-month 

intervals or at the next use, whichever is later. 

8.1.2.1 Make a total of three measurements by 

alternately using zero gas and the specifi ed calibration gas. Record the meter readings. Calculate the 

average algebraic difference between the meter 

readings and the known value. Divide this average difference by the known calibration value and 

multiply by 100 to express the resulting calibration 

precision as a percentage. 

8.1.2.2 The calibration precision shall be equal to or 

less than 10 % of the calibration gas value. 

8.1.3 Response Time. The response time test is required before placing the instrument into service. If a 

modification to the sample pumping system or fl ow 

configuration is made that would change the response 

time, a new test is required before further use. 

8.1.3.1 Introduce zero gas into the instrument 

sample probe. When the meter reading has stabilized, switch quickly to the specifi ed calibration 

gas. After switching, measure the time required to 

attain 90 % of the final stable reading. Perform this 

test sequence three times and record the results. 

Calculate the average response time. 

8.1.3.2 The instrument response time shall be equal 

to or less than 30 seconds. The instrument pump, 

dilution probe (if any), sample probe, and probe 

filter that will be used during testing shall all be in 

place during the response time determination. 

8.2 Instrument Calibration. Calibrate the VOC 

monitoring instrument according to Section 10.0. 

8.3 Individual Source Surveys. 

8.3.1 Type I—Leak Definition Based on Concentration. Place the probe inlet at the surface of the 

component interface where leakage could occur. 

Move the probe along the interface periphery while 

observing the instrument readout. If an increased 

meter reading is observed, slowly sample the interface where leakage is indicated until the maximum 

meter reading is obtained. Leave the probe inlet at 

this maximum reading location for approximately 

two times the instrument response time. If the 

maximum observed meter reading is greater than 

the leak definition in the applicable regulation, 

record and report the results as specified in the 

regulation reporting requirements. Examples of 

the application of this general technique to specifi c 

equipment types are: 

8.3.1.1 Valves. The most common source of leaks 

from valves is the seal between the stem and housing. Place the probe at the interface where the stem 

exits the packing gland and sample the stem circumference. Also, place the probe at the interface 

of the packing gland take-up flange seat and sample 

35

the periphery. In addition, survey valve housings of 

multipart assembly at the surface of all interfaces 

where a leak could occur. 

8.3.1.2 Flanges and Other Connections. For welded 

flanges, place the probe at the outer edge of the 

flange-gasket interface and sample the circumference of the flange. Sample other types of nonpermanent joints (such as threaded connections) with 

a similar traverse. 

8.3.1.3 Pumps and Compressors. Conduct a circumferential traverse at the outer surface of the 

pump or compressor shaft and seal interface. If 

the source is a rotating shaft, position the probe 

inlet within 1 cm of the shaft-seal interface for the 

survey. If the housing configuration prevents a 

complete traverse of the shaft periphery, sample all 

accessible portions. Sample all other joints on the 

pump or compressor housing where leakage could 

occur. 

8.3.1.4 Pressure Relief Devices. Th e confi guration 

of most pressure relief devices prevents sampling 

at the sealing seat interface. For those devices 

equipped with an enclosed extension, or horn, 

place the probe inlet at approximately the center of 

the exhaust area to the atmosphere. 

8.3.1.5 Process Drains. For open drains, place the 

probe inlet at approxima tely the center of the area 

open to the atmosphere. For covered drains, place 

the probe at the surface of the cover interface and 

conduct a peripheral traverse. 

8.3.1.6 Open-ended Lines or Valves. Place the probe 

inlet at approximately the center of the opening to 

the atmosphere. 

Leak Detection and Repair—A Best Practices Guide 

8.3.1.7 Seal System Degassing Vents and Accumulator Vents. Place the probe inlet at approximately 

the center of the opening to the atmosphere. 

8.3.1.8 Access door seals. Place the probe inlet at 

the surface of the door seal interface and conduct a 

peripheral traverse. 

8.3.2 Type II—“No Detectable Emission”. Determine the local ambient VOC concentration around 

the source by moving the probe randomly upwind 

and downwind at a distance of one to two meters 

from the source. If an interference exists with this 

determination due to a nearby emission or leak, the 

local ambient concentration may be determined 

at distances closer to the source, but in no case 

shall the distance be less than 25 centimeters. Th en 

move the probe inlet to the surface of the source 

and determine the concentration as outlined in 

Section 8.3.1. Th e difference between these concentrations determines whether there are no detectable emissions. Record and report the results as 

specified by the regulation. For those cases where 

the regulation requires a specific device installation, or that specified vents be ducted or piped to 

a control device, the existence of these conditions 

shall be visually confirmed. When the regulation 

also requires that no detectable emissions exist, 

visual observations and sampling surveys are required. Examples of this technique are: 

8.3.2.1 Pump or Compressor Seals. If applicable, determine the type of shaft seal. Perform a survey of 

the local area ambient VOC concentration and determine if detectable emissions exist as described 

in Section 8.3.2. 

8.3.2.2 Seal System Degassing Vents, Accumulator 

Vessel Vents, Pressure Relief Devices. If applicable, 

36

Leak Detection and Repair—A Best Practices Guide 

observe whether or not the applicable ducting or 

piping exists. Also, determine if any sources exist in 

the ducting or piping where emissions could occur 

upstream of the control device. If the required ducting or piping exists and there are no sources where 

the emissions could be vented to the atmosphere 

upstream of the control device, then it is presumed 

that no detectable emissions are present. If there 

are sources in the ducting or piping where emissions could be vented or sources where leaks could 

occur, the sampling surveys described in Section 

8.3.2 shall be used to determine if detectable emissions exist. 

8.3.3 Alternative Screening Procedure. 

8.3.3.1 A screening procedure based on the formation of bubbles in a soap solution that is sprayed on 

a potential leak source may be used for those sources that do not have continuously moving parts, that 

do not have surface temperatures greater than the 

boiling point or less than the freezing point of the 

soap solution, that do not have open areas to the 

atmosphere that the soap solution cannot bridge, 

or that do not exhibit evidence of liquid leakage. 

Sources that have these conditions present must be 

surveyed using the instrument technique of Section 

8.3.1 or 8.3.2. 

8.3.3.2 Spray a soap solution over all potential leak 

sources. The soap solution may be a commercially 

available leak detection solution or may be prepared using concentrated detergent and water. A 

pressure sprayer or squeeze bottle may be used to 

dispense the solution. Observe the potential leak 

sites to determine if any bubbles are formed. If 

no bubbles are observed, the source is presumed 

to have no detectable emissions or leaks as applicable. If any bubbles are observed, the instrument 

techniques of Section 8.3.1 or 8.3.2 shall be used 

to determine if a leak exists, or if the source has 

detectable emissions, as applicable. 

37

Leak Detection and Repair—A Best Practices Guide 

9.0 Quality Control 

Section	 Quality control measure Effect


8.1.2....................................... Instrument calibration Ensure precision and accuracy, 

precision check. respectively, of instrument 

response to standard. 

10.0........................................ Instrument calibration. 

10.0 Calibration and Standardization 

10.1 Calibrate the VOC monitoring instrument as 

follows. After the appropriate warmup period and 

zero internal calibration procedure, introduce the 

calibration gas into the instrument sample probe. 

Adjust the instrument meter readout to correspond 

to the calibration gas value. 

Note: If the meter readout cannot be adjusted to 

the proper value, a malfunction of the analyzer 

is indicated and corrective actions are necessary 

before use. 

11.0 Analytical Procedures [Reserved] 

12.0 Data Analyses and Calculations [Reserved] 

13.0 Method Performance [Reserved] 

14.0 Pollution Prevention [Reserved] 

15.0 Waste Management [Reserved] 

16.0 References 

1. Dubose, D.A., and G.E. Harris. Response 

Factors of VOC Analyzers at a Meter Reading of 10,000 ppmv for Selected Organic 

Compounds. U.S. Environmental Protection 

Agency, Research Triangle Park, NC. Publication No. EPA 600/2–81051. September 1981. 

2. 	Brown, G.E., et al. Response Factors of VOC 

Analyzers Calibrated with Methane for 

Selected Organic Compounds. U.S. Environmental Protection Agency, Research Triangle 

Park, NC. Publication No. EPA 600/2–81–022. 

May 1981. 

3. 	DuBose, D.A. et al. Response of Portable 

VOC Analyzers to Chemical Mixtures. U.S. 

Environmental Protection Agency, Research 

Triangle Park, NC. Publication No. EPA 

600/2–81–110. September 1981. 

4. Handbook of Hazardous Materials: Fire, Safety, 

Health. Alliance of American Insurers. Schaumberg, 

IL. 1983. 

17.0 Tables, Diagrams, Flowcharts, and Validation Data [Reserved] 

38

Leak Detection and Repair—A Best Practices Guide 

Appendix E 	 Summary of NEIC Comparative Monitoring Results of Leaking Valves at 17 Refi neries 

Refineries Total NEIC Total 

Valves Monitored 170,717 47,526 

Number of Leaks 2,266 2,372 

Leak Rate (%) 1.3 5.0 (avg) 

Emissions Rate (lb/hr) 1,177.0 2,775.5 

Potential Emissions 

from Undetected Leaks (lb/ 

hr)a 

1,598.5 

Source: Enforcement Alert – Proper Monitoring Essential to Reducing ‘Fugitive Emissions’ Under 

Leak Detection and Repair Programs, EPA 300-N-99-014. US EPA Office of Enforcement and 

Compliance Assurance. Vol. 2, No. 9, Oct 1999. 

a Potential Emissions from Undetected Leaks (lb/hr) = NEIC Total Emissions Rate (lb/hr) 

– Refineries Total Emissions Rate (lb/hr) 

39

Leak Detection and Repair—A Best Practices Guide


Appendix F Enforcement Alert


40

Leak Detection and Repair—A Best Practices Guide


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Leak Detection and Repair—A Best Practices Guide


42

Leak Detection and Repair—A Best Practices Guide


43

United States 

Environmental Protection 

Agency 

Office of Compliance 

Office of Enforcement and Compliance Assurance 

(mail code) 

EPA-305-D-07-001 

October 2007 

www.epa.gov/compliance