Chemical Engineering May 2014 - 45

Written LDAR compliance
Training
LDAR audits
Table 1. elemenTs of a model ldaR PRogRam
First attempt at repair
Pump, compressor and agitator
Delay of repair compliance assurance
Electronic monitoring and storage of data
Contractor accountability QA/QC of LDAR data
Internal leak definitions
Less frequent monitoring
Calibration/calibration drift assessment
Records maintenance
yond the design, engineering, and
construction phase of building a
facility, the in-service reality of corrosion
can be very different.
Corrosion, in the majority of
cases, does not occur in a uniform
manner. It will most frequently
occur in localized areas in the form
of pits, as erosion at high-impingement
areas, as corrosion under
insulation, at heat-affected zones
(HAZ) where welding was improperly
performed, causing a localized
change to the mechanical or chemical
properties of the material, and
in many other instances in which
unforeseen circumstances create
the potential for corrosion and the
opportunity for leaks in the pipe
itself or in a vessel wall. Because
of that incongruity, corrosion is an
anomaly that, in reality, cannot
wholly be predicted.
Corrosion-rate values found in
various published resources on the
topic of material compatibility are
based on static testing in which a
material coupon is typically set in
a vile containing a corrosive chemical.
This can be done at varying
temperatures and in varying concentrations.
After a period of time,
the coupon is pulled and the rate
of corrosion is assessed. That is a
simplification of the process, but
you get the point. When a material
of construction (MOC) and a potentially
corrosive chemical come
together in operational conditions,
the theoretical foundation upon
which the material selection was
based becomes an ongoing realtime
assessment. This means that due
diligence needs to be paid to examining
areas of particular concern,
depending on operating conditions,
such as circumferential pipe welds
for cracking, high-impingement
areas for abnormal loss of wall
thickness, hydrogen stress-corrosion
cracking (HSCC), and others.
The LDAR program does not
specify the need to check anything
other than mechanical joints for potential
leaks. Monitoring pipe and
vessel walls, particularly at welds
that come in contact with corrosive
chemicals, is a safety consideration
and practical economics. Performing
cursory examinations for such
points of corrosion where the potential
exists should be made part
of any quality assurance or quality
control (QA/QC) and preventive
maintenance program.
Mechanical joints and openended
pipe. Mechanical joints
can include such joining methods
as flanges, unions, threaded joints,
valve bonnets, stem seals and clamp
assemblies. It can also include
pump, compressor and agitator
seals. Other potential points of transient
emissions include open-ended
piping, such as drains, vents, and
the discharge pipe from a pressurerelief
device. Any of these joints or
interfaces can be considered potential
leak points and require both
monitoring and record-keeping documentation
in compliance with the
EPA's LDAR program.
Mechanical joints can leak due to
improper assembly, insufficient or
unequal load on all bolts, improperly
selected gasket type, sufficient
pressure or temperature swings
that can cause bolts to exceed their
elastic range (diminishing their
compressive load on the joint), and
an improperly performed " hot-bolting "
procedure in which in-service
bolts are replaced while the pipeline
remains in service. " Hot bolting " is
not a recommended procedure, but
is nonetheless done on occasion.
seals can develop leaks where shaft
misalignment plays a part. If the
shaft is not installed within recommended
tolerances or if it becomes
misaligned over time there is a
good possibility the seal will begin
to fail.
The LDAR program
Promulgated in 1970 and amended
in 1977 and 1990, the Clean Air
Act requires that manufacturers
producing or handling VOCs
develop and maintain an LDAR
program in accordance with the
requirements set forth under the
Clean Air Act. This program monitors
and documents leaks of VOCs
in accordance with Method 21 -
Determination of Volatile Organic
Compound Leaks.
Table 1 provides a listing of key
elements that should be contained
in an LDAR program. Those elements
are described as follows:
Written LDAR compliance. Compile
a written procedure declaring
and defining regulatory requirements
that pertain to your specific
facility. This should include recordkeeping
certifications; monitoring
and repair procedures; name, title,
and work description of each personnel
assignment on the LDAR team;
required procedures for compiling
test data; and a listing of all process
units subject to federal, state and
local LDAR regulations.
Training. Assigned members of
the LDAR team should have some
experience base that includes work
performed in or around the types of
piping systems they will be testing
and monitoring under the LDAR
program. Their training should include
familiarization with Method
21 and also training as to the correct
procedure for how to examine
the various interface connections
they will be testing. They should
also receive training on the test
instrument they will be using and
how to enter the test data in the
proper manner. All of this needs to
be described in the procedure.
LDAR audits. An internal audit
team should be established to ensure
that the program is being carChemiCal
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Chemical Engineering May 2014

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