|
RCFA
Saves Inland Steel $1.15 Million
|
|
By John Van Auken, Inland
Steel Co.
|
|
Inland Steel is committed to improving the reliability of its plant operations
to reduce costs and downtime and increase productivity. Recognizing that
substantial savings could be achieved by reducing or eliminating chronic
system and equipment failures, the company provided extensive training
in root cause failure analysis (RCFA) to 50 reliability engineers and more
than 150 field employees. |
|
The RCFA training, conducted by Reliability Center, Inc., emphasized the
importance of approaching failure problems in a systematic, logical process
and provided a proven methodology to identify, analyze, and verify the
root causes of recurring failures. |
|
The classroom training provided a valuable base of knowledge and skills,
but applying these skills in actual workplace situations is the real test.
The company recently had an opportunity to do that and the results were
gratifying, not only in measurable savings but also in the satisfaction
that comes from tackling a problem and solving it. |
| The
Problem |
|
There had been nine catastrophic failures of the lance carriage assemblies
in the site's basic oxygen furnaces at an approximate cost of $250,000
each. The mean time between failure (NITBF) of these occurrences was 2.5
months. |
|
The lance carriage assembly is an elevator weighing approximately 11 tons
that raises and lowers an oxygen lance, a mechanism that blows pure oxygen
about 80 ft at a speed of Mach 2 in and out of the steel-making vessel. |
|
|
This
logic tree describes the failure event and shows all possible modes of
failure. The most significant failure modes are prioritized.
|
|
The lance provides the agitation to mix the "recipe" according to customer
specifications. The recurring failure of the assembly presented an opportunity
to use RCFA in the field. |
|
The classroom training included a five-step method for addressing failures:
preserve failure data, order the analysis, analyze the data, communicate
findings and recommendations, and track to ensure results. |
|
This method compelled the failure analysis team to arrive at logical, verifiable,
fact-based conclusions rather than solutions based on guesswork, hunches,
or conventional wisdom. Therefore, the team had confidence in its analysis
work and a high degree of certainty that its findings and recommendations
would solve the problem. |
| Applying
the Methodology |
|
The first action was to collect, preserve, label, log, and analyze all
data and parts related to the failure. |
|
The next step was to assemble a multidisciplined team to analyze the failure.
Operations, maintenance, and technical representatives were included. The
principal analyst had an electrical background even though the failure
appeared to have mechanical roots. His background allowed him to be unbiased
and to facilitate the analysis process rather than guide the team to a
preconceived conclusion. |
|
The team was faced with taking the pieces of the puzzle formulated from
the failure information and putting them together. A logic tree was used,
which promoted a disciplined, logical deduction process that forced the
team to work backward from failure to physical and latent root causes. |
|
Hypotheses were developed to determine how an event occurred. When all
possibilities had been identified, strategies were developed to verify
whether the event did or did not happen. Without the failure information,
it would not have been possible to verify the hypotheses. |
|
The team kept working until the tree was down to its roots. Two appropriate
questions were asked repeatedly until all the roots were uncovered. The
first question, "How can that happen?" was followed by "Why did it happen?"
Using this method, the team uncovered the physical root causes of the failure
along with the human and organizational root causes. |
|
Certain management or organizational systems (for example, improper lug
nut specifications, improper torquing and alignment procedures, and lack
of parts inventory) were influencing field employees in making decisions
that led to failure. When the RCFA process was completed, the solutions
to the failure were apparent. The next step was to present the team's findings
and recommendations in a way that would encourage corrective actions. |
|
The team developed recommendations that they felt management would accept.
The recommendations were reviewed a second time because they represented
what the team felt would be a permanent solution. The team tried to reject
subjectivity and stick to objective solutions based on root causes. |
|
The final presentation to management was designed to convey the information
effectively. It was an electronic presentation with pertinent photographs
digitized so they could be viewed on a screen. Appropriate parts were passed
around so management could see firsthand what the slides depicted. |
|
Management appreciated the level of detail and logical approach. The recommendations
were accepted, long-term plans developed, responsibilities assigned, and
timetables set. |
|
The immediate actions were to realign the equipment to precision specifications
and implement mechanical techniques that would address the physical roots.
Because of perceived higher priorities, organizational recommendations
including providing alignment training, developing a torquing procedure,
and clearing up problems between central and assigned maintenance and inspection
responsibilities were not addressed. |
|
However, after changes regarding the physical roots were made, there was
not another lance drop for 10 months, resulting in savings of approx-imately
$1.15 million compared to past performance. |
|
When a "mini" RCFA was performed on the latest lance drop, it was found
that 10 of the 11 contributors to the failure had exactly the same roots
identified in the initial RCFA. Because action on these recommendations
was delayed, another failure occurred. This event reinforced the fact that
prompt follow-through on all the recommendations of the RCFA was vital.
Currently, the MTBF has improved from 2.5 months to 10 months and it continues
to increase month by month. |
|
|
Graphic representation
of the failure event shows the oxygen lance carriage falling, hitting the
floor, and the cable being cut. A five-step method was used to address
the failure.
|
| Management
Support is Key |
|
The results achieved would have been impossible without strong support
from management. That support must be active and it must include providing
the principal analysts and their teams with the time to meet and analyze
failure information. Management must provide the technical, field, or administrative
resources required to verify hypotheses. |
|
When the systems or lack of systems by which the organization runs are
identified, the benefits of analyses can be leveraged to other units. For
example, when the lack of knowledge on how to properly align the equipment
was confirmed, it was found that the problem was common to other areas.
The same proved to be true for effective torquing. |
|
Many recommendations from the RCFA on the lance carriage assembly failure
were implemented site wide. Perhaps the greatest benefit of the entire
process has been that other areas learned from this failure and were able
to prevent failures of their own. |
|
Now when there is a failure, no one jumps right in and tries to fix it.
A mini RCFA is performed, including the collection of appropriate failure
information. This information is used to develop and implement countermeasures.
The results are fewer delays, longer MTBF, and more reliable production. |
RCI Offers the full
range of Reliability Consulting Services and Training Programs for Industry.
We conduct facilitations, reliability assessments, FMEA & Root Cause
Failure Analysis Training - Public & On-Site.
For more information
contact:
Reliability Center, Inc.
P.O. Box 1421
Hopewell, Virginia 23860
Phone: (804) 458-0645
Fax: (804) 452-2119
Website: http://www.reliability.com
|
|
Return
to Failure Analysis Reference Library Index
|
