Partner Reported Opportunities (PROs) PRO Fact Sheet No. 602 for Reducing Methane Emissions 

Test and Repair Pressure Safety Valves 

Technology/Practice Overview 

Description 

If a pressure surge in a compressor,

pipeline, or pressure vessel exceeds the 

maximum operating pressure for the 

system, pressure safety valves (PSVs, or

pressure relief valves, PRVs) will open 

and vent excess gas to the atmosphere. 

Over time, the valve seats wear or 

become fouled with debris, and will leak 

gas. Small leaks will grow larger as the 

leak point erodes or is subject to 

corrosion. 

Gas STAR Partners find that pipeline

valves, connections, compressor valves 

and open-ended lines are major sources 

of fugitive methane emissions. A study

of fugitive emissions in four gas

processing plants found that only 0.4 

percent of leaking equipment

components were pressure relief valves, 

yet they contributed 3.5 percent of the 

total fugitive emissions. 

EPA’s Natural Gas Star Partners report 

a practice of regularly screening PSVs 

for leakage, and repairing them as 

needed. A proactive testing and repair 

program can dramatically reduce 

fugitive methane losses. Some partners 

include screening of PSVs in a directed

inspection and maintenance (DI&M) 

program. 

Estimated 

Gas Price 

Annual 

Methane 

Savings 

Value of 

Annual Whole 

Gas Savings* 

Estimated 

Implementation 

Cost 

Incremental 

Operating Cost 

Payback 

(months) 

$7.00/Mcf 124 — 

2500 Mcf $923 — $18,000 $250 Data not available 3 months — immediate 

$5.00/Mcf 124 — 

2500 Mcf $660 — $13,300 $250 Data not available 5 months — immediate 

$3.00/Mcf 124 — 

2500 Mcf $395 — $7800 $250 Data not available 8 months —  1 month 

Economic and Environmental Benefits 

Economic Evaluation 

 Gas savings and reducing methane emissions 

 Improved operational readiness and equipment safety 

Additional Benefits: 

Estimated annual methane emission reductions 124 Mcf – 2,500 Mcf per leaking PSV 

Methane Savings 

* Whole gas savings are calculated using a conversion factor of 94% methane in pipeline quality natural gas. 

Compressors/Engines 

Dehydrators 

Directed Inspection & 

Maintenance 

Pipelines 

Pneumatics/Controls 

Tanks 

Valves 

Wells 

Other 

Applicable Sector(s) 

Production 

Processing 

Transmission 

Distribution 

Other Related Documents: 

Replace Burst Plates with 

Secondary Relief Valves, 

PRO No. 605 

Conduct DI&M at Remote 

Facilities, 

PRO No. 901 
 

 

 

 

 

Source: U.S. EPA, Natural Gas STAR Program 

PRO Fact Sheet No. 602 Continued 

Test and Repair Pressure Safety Valves (Cont’) 

Schematic Showing a Pressure Relief Valve on Compressor Piping 

Compressor 

Drain Valve 

Pressure Relief Valve 

Dehydrator 

Controllers 

Operating Requirements 

While PSVs are in service, screening to locate leaking 

valves can be accomplished with an organic or toxic 

vapor analyzer (OVA,TVA), acoustic and ultrasound leak

detection, or optical imaging using an infrared camera. 

If leaks are detected, options available to quantify the

leak volume include a high volume sampler, bagging

techniques or a rotameter. Additionally, acoustic and 

ultrasonic leak detectors often include an estimation 

algorithm which enables calculation of emission volumes 

based on the device’s reading. Once quantified, leaks are 

fixed, or tagged and prioritized for future repair. 

Applicability 

Partners find that infrared imaging is an efficient 

approach to identify leaking valves, providing a real time

visual image of the leaks. Optical techniques also offer 

qualitative assessment of leak size for inaccessible areas 

by simply viewing them. Partners report that the highvolume sampler is often the most effective tool for 

quantifying leaks and identifying cost-effective repairs. 

This approach of rapidly screening, evaluating and 

repairing leaks can be applied to pressure safety valves 

on all types of equipment in all natural gas industry 

sectors. 

Methane Emissions 

The volume of fugitive

methane emissions from PSVs 

will depend on the age of the

equipment, operating pressure 

and equipment maintenance.

An industry study1 estimated 

average annual methane 

emissions from leaking PSVs 

in gas processing plants to be

844 Mcf per valve; Gas STAR 

partners report a wide range 

of methane emissions 

depending on their operations. 

One partner screened 

approximately 100 pressure 

relief valves and found 25 

percent to be leaking. Twenty 

-five valves were repaired

yielding total methane savings 

of 500 Mcf, approximately 20

Mcf per PSV. A distribution 

partner repaired 4 pressure 

safety valves on compressor discharge lines for savings of 

124 Mcf per valve. Another distribution partner 

repaired two compressor discharge relief valves, saving 

467 Mcf per valve. Two gate station pressure safety

valves with a history of leaking were replaced, producing

total savings of 5000 Mcf. 

In high pressure applications, leaking PSVs can be a

major source of methane emissions. One partner

reported that a leaking one-inch pressure relief valve 

emitted almost 36,744 Mcf/year. Five man-hours of 

labor and $125 of material eliminated the leak, 

producing annualized savings of more than $110,000 at 

$3.00/Mcf. 

The average methane content of natural gas varies by natural gas 

industry sector. The Natural Gas STAR Program assumes the 

following methane content of natural gas when estimating methane savings for Partner Reported Opportunities. 

Production 79 % 

Processing 87 % 

Transmission and Distribution 94 % 

Methane Content of Natural Gas 

2 
 

 

 

 

 

PRO Fact Sheet No. 602 Continued 

Test and Repair Pressure Safety Valves (Cont’) 

Economic Analysis 

Basis for Costs and Savings 

Typical total repair costs (labor and materials) for 

leaking PSVs are expected to range from approximately 

$75 to $250 per valve in current dollars.2 The cost of 

complicated repairs that require significant labor will

likely be higher. This analysis assumes a range of 

Partner-reported annual emissions savings from 124 Mcf 

to 2500 Mcf, and the high-end estimated repair cost of 

Pressure Relief Valves on Separators at a Production Site 

Source: Advanced Resources International 

$250 per valve. At gas prices ranging from $3.00 to

$7.00, the PSV repairs pay back almost immediately for 

the large leak example (2500 Mcf), and within 3 to 8

months for the small leak example (124 Mcf). 

Discussion 

Testing and repair of leaking pressure safety valves 

provides cost-effective methane savings across a range of 

leak rates, repair costs, and likely gas prices. Depending 

on the age, operating pressure, and equipment 

components of a facility, regular screening and repair of 

leaking PSVs can be part of the facility’s directed 

inspection and maintenance (DI&M) program. Emissions 

from a leaking valve can be substantial for PSVs on high

pressure equipment. If no facility DI&M program is in 

place, a monitoring and repair effort targeting only PSVs 

would be cost-effective and could reduce methane losses 

significantly. 

1.	 Clearstone Engineering, 2002, Identification and Evaluation of Opportunities to 

Reduce Methane Losses at Four Gas Processing Plants.
 

2.	 Ananthakrishna, S. and C. Henderson, 2002, Cost-effective emissions reductions 

through leak detection and repair, Hydrocarbon Processing, May 2002.
 

EPA provides the suggested methane emissions estimating methods contained 

in this document as a tool to develop basic methane emissions estimates only. 

As regulatory reporting demands a higher-level of accuracy, the methane emission estimating methods and terminology contained in this document may not 

conform to the Greenhouse Gas Reporting Rule, 40 CFR Part 98, Subpart W 

methods or those in other EPA regulations. 

2011
 

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