Fugitive Emissions

GBH Enterprises, Ltd.

Manufacturing & Engineering Guide:
GBHE-OE-007

Fugitive Emissions
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Fugitive Emissions

CONTENTS

0

INTRODUCTION

1

SCOPE

2

DEFINITIONS
2.1

3

Fugitive Emission

REDUCTION OF FUGITIVE EMISSIONS
3.1
3.2

3.3
3.4

4

Valves
Machine Seals
3.2.1 Pumps
3.2.2 Compressors
Remakable Joints
Pressure Relief Devices

MONITORING OF FUGITIVE EMISSIONS
4.1

5

Management System

FURTHER INFORMATION
5.1
5.2

Related External Publications
Related Internet Sites


0

INTRODUCTION

The four main sources of Fugitive Emissions on most plants are valves, machine
seals, re-makable joints and pressure relief devices. Other possible sources
include open-ended lines, sampling connections, drains and vents.
Sometimes special precautions are taken to minimize Fugitive Emissions, for
example the use of bellows seal valves. However, generally no special
precautions are taken and the subsequent Fugitive Emissions to atmosphere
represent a significant amount of plant losses.
Regulatory requirements covering Fugitive Emissions exist in many countries
and therefore a leak reduction program should be implemented. Fugitive
Emissions also represent financial losses to the business as well as potential
damage to the environment.

1

SCOPE

The purpose of this Information is to provide Engineers with guidance on the
reduction and monitoring methods for Fugitive Emissions.
This document does not summarize legal requirements; however, the relevant
regulatory requirements that apply should be complied with.

2

DEFINITIONS

2.1

Fugitive Emission

Any chemical or mixture of chemicals in any physical form that represents an
unanticipated or spurious leak from anywhere on an industrial site.

3

REDUCTION OF FUGITIVE EMISSIONS

The possibility of Fugitive Emissions can be reduced if consideration is given to
the following generic points when maintenance work is being carried out.
(a)
(b)
(c)
(d)

Ensure the correct specification of the equipment.
Follow the installation procedures and relevant good practices.
Ensure the correct level of competence of personnel.
Ensure the correct start-up procedures are adhered to.


The following measures can be taken to further reduce Fugitive Emissions.
3.1

Valves

Valve gland leaks represent the largest source of Fugitive Emissions in process
areas.
The contribution of individual valves varies widely; those operated most
frequently (control valves, actuated valves) will usually have the highest leak
rates. Rising stem valves such as gate and globe valves are generally worse
than quarter turn valves such as ball or plug valves. Remotely located valves,
whose maintenance and monitoring are difficult, tend to have high leak rates.
The highest emission rates recorded are on valves in gaseous service, followed
by valves on light liquid service. Valves on heavy liquid service usually have very
small losses.
Fugitive Emissions can be practically eliminated with a sealed metal bellows and
a downstream safety gland or equivalent sealing systems and effectively reduced
with modern packing materials such as PTFE, aramid or graphite. The material
needs to be suitable for use with the process conditions (e.g. pressure,
temperature, fluid handled).
It is normal to re-tighten the gland at least two or three times before the valve
needs re-packing, however, to prevent damage to the packing or valve ensure
the glands are:
(a)
(b)

Tightened gradually and evenly.
Not over tightened.

3.2

Machine Seals

3.2.1 Pumps
Fugitive Emissions from pumps can be controlled effectively with the aid of:
(a)
(b)
(c)
(d)
(e)

Canned motor pumps.
Magnetic drive pumps.
Multiple mechanical seals with quench or buffer media.
Multiple mechanical seals with a dry seal on the atmosphere side.
Hermetically tight PD pumps such as diaphragm and bellows pumps.


The effectiveness of a buffer media system should be monitored, with leakage
losses discharged to a closed system.
Secondary containment seals can include low technology solutions such as
packing rings, lip seals and throttle bushings and high technology solutions such
as dry-running contacting mechanical seals, pressure-activated stand-by
mechanical seals and non-contacting mechanical seals.
Fugitive Emissions from pump seals can be kept to a minimum by ensuring:
(a)
(b)
(c)

Vibration and cavitation are avoided.
Correct operation of buffer / barrier systems.
Buffer / barrier fluid circulation is established prior to starting the pump.

Correct installation has a profound influence on the life and performance of shaft
seals.
3.2.2 Compressors
Fugitive Emissions from compressors can be reduced effectively with multiple
sealing systems. In this case the emission of product from wet sealing systems
is prevented by a buffer liquid and from drying sealing systems, for instance, by
using an inert gas quenching medium or extracting the leaking product into a gas
collection system.
3.3

Remakable Joints

In remakable joints the seal is static and therefore they have a low leak
frequency. The combination of high population and low leak frequency means
that it may not be cost effective to introduce a systematic inspection and
maintenance program. For instance, most US regulations require the repair of a
leaking connection when discovered, but do not mandate periodic inspection to
find leaks.
Stress relaxation of gaskets can occur as a result of time, pressure, temperature
or creep. Occasionally, the bolts may loosen as a result of vibration. As a result
flanged joints should be routinely inspected and re-torqued or remade as
appropriate.
To reduce Fugitive Emissions from flanged joints good jointing practice should be
adopted.


3.4

Pressure Relief Devices

Pressure relief devices are an often-overlooked source of Fugitive Emissions as
they are designed to release process fluid under certain conditions. However, it is
wrongly assumed that this is the only time when emissions occur. The potential
causes of leakage from relief valves are chattering or popping (a condition that
occurs when the system pressure comes close to the set pressure of the valve);
improper re-seating of the valve after a relieving operation; and corrosion or
degradation of the valve seat.
To reduce Fugitive Emissions from safety relief valves, a suitably specified
bursting disc should be installed in the inlet line to the safety relief valve.
Consideration should be given to venting safety relief valves in gaseous service
to recovery or flare

4

MONITORING OF FUGITIVE EMISSIONS

Monitoring programs known as LDAR (Leak Detection and Repair) are
considered good practice (and a legal requirement in some countries). To display
a level of compliance, these programs are as a minimum, required to
demonstrate that:
(a)

A register of potential leak sources is maintained, and existing leak
sources are tagged.

(b)

Monitoring is undertaken at regular, defined intervals and recorded in the
register.

(c)

Action is taken to reduce leakage.

A method of weatherproof tagging should be used on any equipment found to be
leaking. The tag should correspond with information logged in the register of
potential leak sources, such as the equipment’s ID number, the part leaking, ppm
and date found. The tag should remain in place until the equipment is repaired,
after which it should be removed and the date repaired recorded in the register of
potential leak sources. A ‘two-tag’ system is not critical but can be used to
differentiate between equipment with existing leaks and equipment that
frequently leaks and requires more frequent monitoring.
Further information on leak monitoring can be found on the US Environmental
Protection Agency (EPA) website www.epa.gov

Minimum suggested monitoring intervals:
(1)

Accessible components should be inspected quarterly.

(2)

Inaccessible components should be inspected annually.

(3)

Pressure relief devices should be inspected within 14 days after every
functional pressure release.

The inspection frequency for accessible components, except pumps and
compressors, may be changed from quarterly to annually provided the equipment
in question has given leak free service for 1 year.
4.1

Management System

A management system is key to a successful reduction of Fugitive Emissions. A
recommended system would be a database which would allow downloading of
emissions data, generation of maintenance work orders for leaking components,
accurate and timely reports indicating compliance within guidelines and
regulations.

5

FURTHER INFORMATION

5.1

Related External Publications

EEMUA publication 195: Compendium of Information Sheets on Topics Related
to Pressure-Containing Equipment: Information Sheet 22 ''Fugitive Emissions
from Piping Systems and Other Equipment' .
Envirowise publication GG71: Guide for Cost-effective Reduction of Fugitive
Solvent Emissions.
EPA Code of Federal Regulations, Title 40, Part 60, Appendix A. Reference
Method 21 “Determination of volatile organic compound leaks”.
ESA European Emission Legislation: “A Guide to legislation covering the control
of fugitive emissions in Europe”. ESA Publication No 012/00.


5.2

Related Internet Sites

www.europeansealing.com
www.epa.gov

www.eemua.co.uk
www.environment-agency.gov.uk
www.envirowise.gov.uk

- European Sealing Association
(ESA) Homepage
- US Environmental Protection
Agency (EPA) Homepage
- EEMUA Homepage (Europe)
- Environment Agency Homepage (UK)
- Environmental Technology
Best Practice Program (UK).


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