Hydrocarbon Processing - October 2021 - GP-13

MAINTENANCE AND RELIABILITY
Prevent unplanned shutdowns
for LNG liquefaction facilities
P. ZHANG, Gulf LNG Solutions, Houston, Texas
Although an unplanned shutdown is an integrated part of
the operational and safety management system of an operating
plant, unplanned shutdowns for a modern LNG liquefaction
operating facility often become some of the costliest
events for the facility owner. Each of these events negatively
affects the owner's business due to loss of production and reputation.
With today's world transitioning to green energy, the
benefits to LNG owners by adopting an advanced prevention
and maintenance program to prevent unplanned shutdowns
are obvious and financially prudent.
Challenges in preventing unplanned shutdowns. An unplanned
or emergency shutdown of an operating facility due
to safety, asset and environmental risks is a necessary step for
owners to take the process and equipment in emergency to a
safe state. Unfortunately, unplanned shutdowns for a modern
LNG liquefaction facility often become frustrating events for
the owners due to loss of production, which can equate to millions
of dollars daily.
Preventing unplanned shutdowns and finding effective solutions
are challenges facing LNG facility owners in the following
areas:
* Due to the complexity and scale of a modern LNG
facility, the potential failures of all components
cannot be fixed at once during a scheduled
turnaround due to variations of the component
failure rate. Between scheduled shutdowns, a
failure will always occur at a seemingly unexpected
time due to randomness or unpredictability.
* Tens of thousands of active components in an LNG
facility must be maintained simultaneously and
properly to sustain stable operation. The task of a
facility's maintenance team is enormous, especially
when a preventive maintenance approach is used.
* Identifying the potential risk of all component failures
is not an easy task during the engineering design
phase. A limited number of unplanned shutdowns
are initiated automatically as designed (e.g., through
shutdown interlocks). The majority are initiated
manually by the operator depending on situations
onsite, which puts a tremendous amount of pressure
on the facility's operations and maintenance teams.
* The traditional reactive maintenance approach is less
useful in preventing unplanned shutdowns because
the failure and shutdown have already occurred.
* The availability of accurate equipment reliability
and failure rate data is key to the success of a
preventive maintenance program. Sometimes,
equipment breaks down earlier than what the
vendors recommended or predicted from historical
data, which adds more challenges to rectifying
the true turnaround intervals of the equipment in
utilizing a preventive maintenance approach.
* Root causes to failures leading to unplanned
shutdowns vary.
* Many unplanned shutdowns were due to design
deficiency and human error, which are often
nightmares to owners as they are less related to
equipment aging or wear and tear. It is difficult for
a plant maintenance team to tackle such failures
by conventional plant maintenance approaches.
Strategies to prevent unplanned shutdowns. The prevention
of unplanned shutdowns for large-scale and complex
LNG facilities is more than just reducing or minimizing failures.
Owners that adopt advanced prevention and maintenance
programs will be the ultimate winners. While all prevention
and maintenance programs share a common goal to
prevent failures of equipment and reduce downtime, for an
LNG facility, an advanced prevention and maintenance program
should be characterized by:
1. Covering the entire lifecycle of the facility-
i.e., from engineering design through plant operations
2. Adopting preventive and predictive approaches
3. Utilizing advanced technologies in monitoring, data
acquisition and data analysis and management, such
as a computerized maintenance management system.
Implementing such a program requires the owner's systematic
deliberation in the choice of engineering management,
asset management, and operational and safety management,
including a risk management program, an engineer program
or project management consulting (PMC) program, etc.
Prevent unplanned shutdowns for LNG facilities. The history
of the LNG industry has shown that many costly unplanned
shutdowns were rooted to hazards or faults laid in the various
engineering phases-conceptual design, pre-FEED feasibility
studies, FEED and EPC. Likewise, efforts made to ease maintenance
and operability during the engineering phase have been
found to significantly reduce a plant's unplanned shutdowns.
The prevention of unplanned shutdowns can be achieved by
good engineering practices and sound equipment design-selection,
specification and cold-eye review in compliance with
codes, standards and regulations. Some good examples of inherGas
Processing | SEPTEMBER/OCTOBER 2021 13
Hydrocarbon Processing - October 2021

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