Efficient Plant May 2019 - 12

Impact on performance
Low

Fig. 2. A reliability
engineer can reduce
risk at every step of
the STO process, but
his or her intervention
has the greatest effect
early on.

High

feature | operating strategies

Pre-STO
FMEA

Short-term improvement





Criticality-based schedule priorities
Risk analysis for discovery work/
'do or defer' decisions
Opportunisitic improvements
on discovery work

Long-term improvement






Design for reliability on capital projects
Reliability and maintainability improvements
Advanced monitoring, inspection, and
condition-directed work
Prognostics and task-interval optimization

Strategy

Gate

Initiation

Gate

Scoping

Gate

Planning

Gate

Scheduling

Gate

Reliability engineering and risk management

Execution

Post-STO
RCA

Lessons Learned

the STO event because he or she has a well-analyzed understanding of
the operational risks and priorities of those various risks, relative to each
other. This helps to avoid the scenario in which the squeaky wheel gets
the grease because someone complains the loudest and most often.
Once the initial premise is established, it's time for the reliability
engineer to conduct a pre-STO-process FMEA (PFMEA). An FMEA
employs inductive reasoning to anticipate what could go wrong, estimate
the consequences and the likelihood of occurrence, and to evaluate the
effectiveness of existing controls. Each of the three categories is assigned
a score of 1 to 10, with 10 being the highest.
The product of multiplying these scores provides a risk-priority number ranging from 1 to 1,000. The FMEA method was initially developed
to evaluate risks with products such as airplanes or cars, to prioritize
them for improvement, and to measure risk-mitigation progress. It can
easily be applied to processes such as managing an STO event. Sometimes, the PFMEA is called a pre-mortem root-cause analysis (RCA).
Evaluating lessons learned from a site's most-recently completed STO
is a good place to start. This essentially involves conducting a formal
review of a log with analytical notes of everything that went wrong
during the most-recent STO event (see "Manage STO Risk," p. 40,
Efficient Plant, March 2019). Because STOs are conducted periodically,
it's difficult to engrain a corporate memory about how to manage them.
It's not uncommon to see situations where half the staff that worked on
the previous STO have retired or left the company and are, therefore, not
available to support the current event. Consequently, a site must depend
on records and detailed notes from that event in the planning of the
upcoming STO.

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Reliability engineers who are trained-and, it is hoped, certified-on
use of FMEA, RCA, and related tools are ideal candidates for performing
the pre-STO PFMEA. This type of pre-event risk analysis is not trivial.
Allocating sufficient resources to do the PFMEA correctly will result in
fewer surprises during the upcoming STO event.

SCOPE FREEZE, CONTROL
Excessive scope and poor scope control are STO-performance killers. In
most plants, reliability engineers use data from various inspections and
monitoring to evaluate the condition of the equipment and decide which
work should be included and which should be left out. The schedule for
many shutdowns, though, is driven by time-based jobs.
In some cases, time-based jobs must be performed to retain a plant's
license to operate. In other cases, those jobs are reliability driven, wherein
the organization has decided to replace or rebuild equipment, based
upon calendar time and/or operating time. Unfortunately, the interval
for many time-based jobs is guesswork. In the worst instances, they're
the byproduct of a knee-jerk reaction to a failure that bit the organization years or even decades ago. In some cases, the organization doesn't
even know why a particular job is performed at a particular interval-it's
just the way they've always done it. Reliability engineers are trained to
evaluate the validity of these jobs and to either optimize the interval,
convert the job to a condition-based job, and/or address the root cause
and eliminate or reduce the risk. A reliability-engineering challenge can
go a long way in reducing the scope of an STO event.
Keep in mind that a major source of scope creep is break-in work.
Break-in work is that which is requested after the lock-down date. To be

MAY 2019

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Efficient Plant May 2019

Table of Contents for the Digital Edition of Efficient Plant May 2019