Hydrocarbon Processing - December 2021 - 74

Valves, Pumps and Turbomachinery
spection interval should be decreased
or suitable modifications made to improve
the performance. If the PSV is
dismantled, then all internals should be
checked as per vendor guidelines. PSV
internal component failures follow the
typical bathtub curve pattern shown in
FIG. 2. A sudden increase in failure rates
can help the inspector determine the
equipment's useful life.
The precise recording and reporting
FIG. 2. Typical bathtub curve for PSV internal component failures.
effect on the valve
* The extent of any leakage
while in service
* Any other evidence of
malfunctioning
* Whether any rupture disks under
the PSV have been replaced
* Management of Change
(MoC) records and current
status of actions
* Record of any frequency review
exercises (increase/decrease),
along with justification
* RCA related to PSVs
* Drawings of pressure relief
devices (PRDs)
* Historical records of failure/
popped or leaked in field
* Inspection recommendations
record/status
* Test certificates
* Repair record/parts replacement
record
* Spare parts list.
Initial visual inspection. Many types
of deposits or corrosion products in
a PSV may be loose and may drop out
during transportation of the valve to
the shop for inspection, testing, maintenance
and resetting. As soon as a valve
is removed from the system, a visual inspection
should be made. Visual inspection
of a PSV immediately after removal
from service provides important information
about operating conditions. To
minimize errors in the testing and handling
of a PSV, each PSV should carry at
least two identification marks to show
its company equipment, such as identifying
tag, stencil on flanges, plate or
other means.
As per API-576, " Inlet and outlet piping
should also be inspected for the pres74
DECEMBER 2021 | HydrocarbonProcessing.com
ence of internal deposits, and records
should be kept of their condition and
cleaning. If necessary, piping should be
radiographed or dismantled for inspection
and any cleaning to be performed. "
The type of deposits, degree of restriction
due to deposits, and the reason for
PSV removal should be recorded.
If such data is recorded properly with
evidence, it can help significantly in adjusting
accurate inspection intervals.
As-received inspection of PSV in
workshop. After a PSV is removed from
service, a visual inspection is carried out
before cleaning and then it is usually taken
to the shop for inspection and repair.
An important phase of maintenance is
testing to determine the set pressure and
tightness of the valve. This testing is usually
performed on a test block in facilities
for applying pressure to a valve and indicating
the pressure applied. This activity
is termed as " as-received " inspection.
It has been observed at multiple sites
that experienced inspectors are involved
only in the final test of the PSV, while
as-received inspection activity is left for
valve shop technicians who are not fully
aware or trained. A qualified inspector
must attend the as-received inspection
event-this is the heart of an efficient
and cost-effective PM program. This
inspection activity provides clues about
the actual PSV performance during operation
and suggests what actions or
steps should be taken to improve its performance
in the future.
Intervals between PSV testing should
be determined by the performance of
the valves in the particular service. If
the as-received test results are erratic
or vary significantly from the cold differential
test pressure (CDTP), the informat
in a PSV testing program depends
on each individual company's methodologies;
however, as a guideline, key points
mentioned in FIG. 2 and API-576 should
be recorded clearly in the test certificate.
Final testing,
test results review
and record update. Before sending
the PSV to the plant or warehouse, a final
test should be conducted. Refer to
API-576 for key points to be recorded
during this final test.
The improper shipment and transportation
of PSVs can have detrimental
effects on device operation. Refer to
API-576 for detailed guidelines regarding
transportation.
Once inspections are completed, the
results should be updated in the site
inspection management software and
approved by the inspection supervisor.
Any pending actions should be recorded
and tracked until implementation. Risk
assessment should be carried out by a
team if critical recommendations cannot
be implemented immediately. The duties
and responsibilities for all involved
in an inspection and testing program for
PSVs should be clearly defined.
Takeaway. The inspection of PSVs provides
data that can be evaluated to determine
a safe and economical frequency
of scheduled inspections. Historical records
reflecting periodic test results and
service experiences for each relief device
should be recorded in full details, as
these are valuable leading indicators of
asset integrity.
JABRAN YOUNAS is the Senior
Inspection Supervisor at EFERT.
He has more than 17 yr of hands-on
experience in the field of nondestructive
testing and inspection
of plant static equipment. He holds
various API , ASNT and NCNDT
certifications and has worked in different fertilizer and
petrochemical units in Pakistan and the Middle East
as a Senior Inspection Supervisor.
http://www.HydrocarbonProcessing.com
Hydrocarbon Processing - December 2021

Table of Contents for the Digital Edition of Hydrocarbon Processing - December 2021
