Equipment leaks such as valves, connectors and pumps are the largest contributors of VOCs and
HAPs from petroleum and chemical processing plants. These are major contributors to ground-level ozone, which is a major component of smog and contributes to respiratory illnesses. Some
are known or suspected carcinogens.
Ninety percent of emissions come from valves and connectors, with valves being the worst offenders. The guide proposes the use of the LDAR program and best available sealing technologies.
A well-executed LDAR program was found to lower emissions, improve workplace and environmental safety and reduce non-compliance violations and penalties.
These include identifying leaking components; comparing leakage levels to compliance requirements; ongoing monitoring and measurement; repairs; and recording and maintaining data and
corrective actions.
Inspector audits indicated that Method 21 has not been consistently followed. EPA estimates that
undetected leaks account for an additional 40,000 tons of VOC emitted annually from refineries.
Table 2. Summary of EPA-305-D-07-001, Leak Detection and Repair—A Best Practices Guide
2.0) Why regulate equipment
leaks?
3.0) Sources, causes and control
of equipment leaks
4.0) What are the benefits of
an LDAR program?
5.0) Elements of LDAR program
6.0) What compliance problems
with current LDAR
programs?
7.0) Model LDAR program
The program needs to be written, communicated, audited and have assigned accountabilities.
gas imaging to find leaks through a
device that looks like a video camera and
has forward-looking infrared (FLIR),
which shows leaks as black trails of
vapor (Figures 2a and 2b), using the differential between the process stream and
the ambient background temperatures.
Table 3 lists key attributes of monitoring and compares the traditional
Method 21 work practice with AWP.
American Petroleum Institute (API)
Publication 310, November 2007, which
is entitled: “Analysis of Refinery Screening Data,” supports monitoring methods
for identifying large leaks. API notes
that just 0.13% of system components
are responsible for over 90% of the con-
trollable fugitive emissions. Of those,
most leak at levels high enough to be
detectable with infrared cameras.
Another study2, which was presented
at the 2008 American Institute of Chemical Engineers Spring National Meeting
by three ExxonMobil Chemical staff
members, reported that generally,
smaller leaks are not found to grow into
large ones. (The study was entitled
“Smart LDAR: Pipe Dream or Potential
Reality?” because it focused on high-leakage components rather than monitoring them all as required by Method
21; the AWP Method has come to be
known as “Smart LDAR.”)
The authors also found that more
© COPYRIGH T FLIR SYS TEMS
fugitive emissions were contained by
quickly finding and repairing these large
leaks with the AWP method than by
wasting time and effort looking for small
ones that might have been missed. These
studies suggest that a proactive
approach to finding and fixing large
leaks is the most practicable way of
reducing fugitive emissions.
Once detected, leaks must be repaired
within time limits specified by the applicable regulations. For a valve stem seal,
this may be as simple as adjusting the
gland nuts or replacing the packing. In
extreme cases, compliance might require
hot tapping or completely replacing the
valve. Because of this, selecting, qualify-
© COPYRIGH T FLIR SYSTEMS
Figure 2a. AWP employs a camera-like device using forward-looking
infrared optical gas imaging to detect leaking components.
