Root Cause Analysis

Another look at the Exxon Valdez oil spill

The Supreme Court has begun hearing Exxon Mobil Corp.’s appeal of punitive damages stemming from the 1989 oil spill caused by the grounding of the EXXON VALDEZ.   The punitive damages currently stand at $2.5 billion, reduced by appeals from the original punitive damages of $5 billion.  People across the country are eagerly awaiting the Supreme Court’s decision, which is expected in the summer, for many reasons.  While this case has several interesting legal ramifications, the one I’d like to focus on is Exxon Mobil Corp.’s liability, and how a root cause analysis can help us foresee the different areas where liability might be at issue.  When examining the causes of the EXXON VALDEZ spill, a very basic root cause analysis follows: 

What a lot of people imagine when they hear about the EXXON VALDEZ, and what the cause map above implies, is a drunken Captain haphazardly steering a gigantic oil tanker into a reef.  As is usually the case, the real issue is far more complicated.  Many people don’t realize that the Captain was not even present on the bridge when the ship struck the reef.  So his drinking did not directly cause the accident.  Yet the fact that he was drunk, which was against company regulations, is one of the main reasons that Exxon Mobil Corp. is being found liable for punitive damages.  The argument is that they knew the Captain had an alcohol problem and still allowed him to pilot the ship.  We’d have to expand upon the cause map above significantly before there was any mention of Exxon Mobil Corp. and their contribution (direct and indirect) to the spill.  A visual root cause analysis expanding upon the last two boxes is shown below.

This is why a visual form of the root cause analysis is so helpful.  Indirect causes are the easiest ones to miss, and they are frequently the biggest liability issues.  A detailed cause map allows us to see the indirect causes that can lead to liability issues - such Exxon Mobil Corp.’s inaction towards the Captain’s violation of company rules, which is part of the basis of Exxon Mobil Corp.’s liability in the ongoing litigation.  It’s only when we get down to the nitty-gritty of the root cause analysis that we can see the contributions from all the major players.  It will be interesting to see what kind of a price tag the Supreme Court will place on those contributions.

Problem Solvers are Specific

Have you ever heard anyone say “the procedure is a piece of junk?”  If you ask the person if every step of the 40-step procedure is wrong they will usually say “No, not every step.”  You can ask them to show you which step is wrong.  When they point out that step 14 is wrong, you can ask, “Is every word in step 14 wrong?”  They will usually say “Well, no, not every word, but that 5 is supposed to be a 7.  You can then say “I understand.  That is an issue.  Thanks for catching that.  I’ll get it updated.  These things have got to be clear and accurate.”

The original statement “the procedure is a piece of junk” is too general.  It refers to the procedure as one thing, not 40 things.  People that blame and complain speak in very general terms.  They group things together and generalize.  People that are very good at troubleshooting and solving problems naturally think and speak in very specific terms.  Analyzing a problem is about breaking a problem down into parts.  Analyzing problems is always about getting more specific so that very specific actions (the solutions) can be taken.

Terms like “human error”, “procedure not followed” and “training less than adequate” are used regularly by companies to explain why a particular problem occurred.  These terms are too general.  They inadvertently give the impression that the cause has been found during their analysis (root cause analysis).  Knowing that someone didn’t follow a procedure is important, but is not the end of an investigation.  We’re just getting to the good stuff.  We’re just getting the specific information that created the incident in the first place.

Our interest is not limited to fixing that person that didn’t follow that procedure.  We want to address how we developed, approved, utilized and updated this particular procedure so that the procedure process can be improved.  It’s about improving how we capture and communicate the best work practices in our organization as a whole.  This is the leverage within the organization.  To solve problems effectively be specific.  Ask those who blame and complain to help us understand the issue by being more specific.

For more information about improving the problem solving skills within your organization, visit ThinkReliability - specializing in Cause Mapping - Effective Root Cause Analysis training.

Dust Explosions: How do we prevent them from happening?

The Chemical Safety Board Investigations Manager, Stephen Selk, P.E. gave a briefing on February 17, 2008 to update to the public on the Imperial Sugar Company explosion and to provide a root cause analysis on dust explosions.  The speech was very enlightening.  One of the things he said was “The Board identified 281 [dust] fires and explosions over a 25-year period that took 119 lives and caused 718 injuries.”  So, obviously this is a concern.  But what to do about it?

When he presented the root cause analysis for dust explosions, he stated that five things were necessary for an explosion: presence of a combustible dust, presence of oxygen, dispersion of the dust into the air, confinement of the particles, and ignition energy.  For each of these requirements in the root cause analysis, there is a possible solution - but that possible solution may or may not be effective.

First, a dust explosion requires the presence of a combustible dust.  Unfortunately, the combustible dust is usually a by-product (or the actual product) of the process being performed.  The Imperial Sugar Company explosion was caused by sugar dust.  The Imperial Sugar Company refines sugar.  Sugar dust will always be present at a sugar refinery.  So, attempting to remove the combustible gas is probably not worthwhile.

What about the presence of oxygen?  Obviously, there has to be oxygen in the refinery itself for the workers to be able to breathe, but it may be possible to remove the oxygen within some of the equipment, possibly by the use of inerting equipment.  Inerting equipment using nitrogen to reduce the percentage of oxygen to below combustible levels has been used with some success in various industries and was recommended as a solution to the fuel tank explosion on TWA Flight 800.  The use of inerting equipment within processing equipment would help reduce explosions that are begun within the equipment.

I’d like to examine dispersion of the dust and confinement together.  These two requirements almost seem to be mutually exclusive.  After all, if the particles are dispersed, they aren’t being confined.  Likewise, if the particles are confined, how are they dispersed?  In reality, the particles are always confined, even if it is only by the building surrounding the processing plant.  It’s not clear how much confinement, or how much dispersion, is required for an explosion to occur.  It’s also likely dependent on the particular organic material that has become combustible dust.  So, specific solutions here would need to be tailored for each individual plant - and there may not be any that truly work.  However, there is one solution that may prevent, or lessen the effects of, follow-on explosions.  That is a blast-proof building.  In the type of blast-proof building I’m thinking of, there is a weaker section of the building that acts almost like a pressure-relief valve.  It blows out before the rest of the building and directs the explosion through a particular path.  (If the processing equipment involves hazardous materials, it could even direct it to another confined area to prevent environmental contamination.)  This solution, too, would need to be designed specifically for the task at hand, and may be prohibitively expensive.

Last, let’s focus on ignition energy.  Eliminating all sources of ignition energy in a plant seems like it would be possible, albeit complicated and possibly prohibitively expensive.  However, with greater thought, eliminating all ignition sources, including static electricity, in a plant filled with electronic equipment and wiring seems like a monumental task indeed.  However, this is where the focus on preventing explosions frequently lies.  This requires constant and careful inspection of all wiring and potential power sources.  Another consideration is that fire is a potential ignition source.  Obviously a goal of any organization is always to avoid fires in the processing equipment, but if preventing ignition is to be the primary way to avoid dust explosions, improved fire extinguishing systems may be required.  If dust explosion is a risk, automatic fire extinguishing systems should be considered.

Preventing dust explosions is a daunting task.  But we see as we examine the statistics - 281 fires and explosions over 25 years, many of them destroying lives and buildings - it is something that must be done.  Once we have completed the root cause analysis, we can look for solutions and then set about implementing them.