Deadly Hydrogen Sulfide Accident Puts Deer Park in Headlines Again

 

A friend once summarized much of engineering ethics to me in two words:  "No headlines."  If that's a good guideline for engineering ethics, the city of Deer Park has seen two major violations of it in less than a month. 

 

Following a giant pipeline fire that burned for four days in September, on last Thursday, Oct. 10, some contract employees at the PEMEX refinery in Deer Park were working on a pipe flange, and something went wrong, releasing the pipe's contents into the air.  They may or may not have known that the pipe was carrying hydrogen sulfide (H₂S), which is a byproduct of oil refining.  It is probably familiar to most readers as the "rotten egg" odor that comes from aged chicken products and sewer gas.  The human nose can detect it at concentrations as low as one part per billion.  Unfortunately, one of its toxic effects is to deaden the olfactory nerves, causing the perceived smell to go away and leading to a false sense of security as concentrations increase.  It is highly toxic, and concentrations as low as 100 parts per million are classified as "immediately dangerous to life and health."

 

Two contract workers died in the accident, which occurred around 4:40 in the afternoon, and 35 others were exposed to the gas to the extent of needing treatment.  The bodies were not recovered until 3:30 AM the next day after the area had been cleared of toxic gas.

 

The city of Deer Park sent out shelter-in-place orders to its residents around 6:30 PM, but due to technical difficulties with the alert system, some people were not alerted until they read about the incident on social media.  A supplemental siren system in the city is due for an upgrade soon.

 

The accident is under investigation by both local authorities and the U. S. Chemical Safety and Hazard Investigation Board, but no cause has yet been determined. 

 

As we noted two weeks ago when writing about the pipeline fire, residents of Deer Park and surrounding communities in Houston are no strangers to refinery-related emergencies.  Release of toxic chemicals in oil refineries has been happening ever since there were refineries, and the industry has adapted to steadily increasing standards for air and water pollution control and safety measures over the decades.  The PEMEX refinery where this accident occurred dates back to 1929, when it was built by Shell Oil.  In 1993, Shell sold half the facility to the Mexican national petroleum company PEMEX and operated it as a joint venture until 2022, at which point Shell sold its share and PEMEX became the sole owner and operator.  This change of ownership may or may not have anything to do with the accident, but management cultures can change with ownership changes, and the upcoming investigation may answer that question as well as many others.

 

Considering the extremes of temperature and pressure under which highly flammable and toxic chemicals are processed in refineries, it's a wonder that we don't have a refinery explosion every day.  But it's the job of engineers to make sure that every possible thing that can go wrong in a refinery is anticipated and forestalled, and far more than 99.9% of the time, this foresight prevents mishaps. 

 

As with airline accidents, by far the most frequent cause of chemical-plant accidents is human error rather than a simple failure of machinery, although the two can be mixed.  The accident in question could have happened because the workers involved misidentified a flange to be worked on.  An oil refinery is one of the most complicated pieces of plumbing on earth, with thousands of valves, flanges, pipes, processing units, and interconnections.  Refinery workers have to know exactly what they are dealing with before taking any action that could conceivably release a product, and it might have been a case of simply opening the wrong flange.  Or an operator may have believed that the pipe in question had been purged of H₂S when in fact it hadn't been.  You can't tell the contents of a steel pipe just by looking, so there must be elaborate protocols in place to verify what is where, especially when maintenance operations are in progress. 

 

It is incidents like this one which make refineries and petrochemical plants high on the NIMBY list—"not in my back yard."  Given that a country wants to have fossil-fuel products, and given that it has considerable expertise and resources to make them, we in the U. S. must have refineries somewhere.  According to a list of new refineries compiled by the U. S. Energy Information Agency, the U. S. refining industry has managed to add considerable refining capacity since 2014 by building new refineries, but they tend to be in or near existing ones—Houston, Corpus Christi, or various locations in Alaska.  It's a lot easier to upgrade an existing refinery or build a new one next to an existing one, than it is to install the infrastructure of pipelines and shipping facilities in a place without refineries at all.

 

For the foreseeable future, the global economy will rely on fossil fuels, and so we will have to put up with refineries and everything that goes with them.  But people who live near them and work in them have a right to expect that they will be operated as safely as human ingenuity can manage. 

 

That was obviously not the case at the PEMEX plant last week.  We will follow this accident in the future, and when the investigation concludes, perhaps we will learn what chain of events led to an accident that killed two people and endangered an entire community.  But until then, we can take some comfort in the fact that refineries rarely show up in headlines, despite all the dangerous stuff going on in them.

 

Sources:  I referred to articles on the H₂S accident by ABC News 13 in Houston at https://abc13.com/post/pemex-chemical-leak-crews-waiting-lower-levels-before-entering-unit-center-deadly-hydrogen-sulfide-deer-park/15416337/, an article in the Saturday Oct. 12 edition of the Austin American-Statesman, "2 dead, dozens of others injured in hydrogen sulfide leak near Houston," and the Wikipedia article on PEMEX Deer Park.  The Energy Information Agency data is from https://www.eia.gov/tools/faqs/faq.php.

Deer Park Pipeline Fire Raises Questions

 

Around 10 A. M. Monday, Sept. 16, someone in a white SUV drove it through a chain-link fence in Deer Park, Texas and straight into the above-ground valve structure of an Energy Transfer Company liquefied-natural-gas underground pipeline in the city of Deer Park, Texas.  When the pipe failed, it released the several hundred pounds per square inch of pressure that was keeping the material liquid along the miles of pipe that led to the valve.  The liquid began boiling into gas, and spewed out a column of white vapor that immediately caught fire. 

 

The resulting flame towered a hundred feet or more in the air and produced a plume of black smoke that could be seen for miles.   The fire burned for four days, from Monday to Thursday, and was so big that International Space Station astronaut Don Pettit could see it from space and sent a photo down to prove it.  Four people were injured, houses near the site were evacuated, and millions of dollars of damage was caused by the fire before it finally burned itself out sometime on Thursday Sept. 19.  Once it was safe to approach the area, medical examiners recovered a body from the vehicle that caused the fire.

 

Residents of the now somewhat-ironically-named Deer Park are no strangers to petrochemical disasters.  Living in one of the most concentrated areas of oil refining and petrochemical production in the world has both advantages and disadvantages.  Some of the advantages are that there are usually plenty of good, stable jobs for people who are willing to work hard and take risks, and the city's tax base is jet-propelled by billions of dollars invested in plants and equipment.  Some of the disadvantages are that you live in an atmosphere that is never entirely free of chemicals that may have long-term health risks, and sometimes things happen that pose more immediate dangers, for example a fire that melts the interior of the car that you had to abandon during an evacuation.

 

Partly to avoid insurance costs that would bankrupt any business, the refinery and petrochemical industries are some of the most safety-conscious in the world.  I was once privileged to take a tour inside a working refinery, after viewing them from afar for most of my growing-up life in Texas.  To gain this privilege, I had to sit through an hour-long series of training videos, sign a form, and when it got time to take the tour, all they did was load us on a bus and drive us through the place, maybe with a fire truck following after, I don't exactly recall. 

 

But despite the best safety precautions human minds can devise, other human minds can come up with ways to thwart them.  A friend of mine who lived and worked in Deer Park for many years has told me that the accident happened in a large right-of-way that carries many pipelines interconnecting the various plants in the Deer Park and La Porte area, which is on the Houston Ship Channel.  A video captured at the time of the accident shows the SUV in question traveling well above the speed limit and steering straight for the valve assembly.  Although the body recovered from the wreckage of the truck has not yet been publicly identified, reasonable speculation is that it is a case of suicide committed by someone who might have had inside knowledge of which valve to hit.  Although terrorism isn't suspected by the authorities, the investigation is too new to have produced much in the way of firm results.

 

Some residents of the area have called for additional protection for vulnerable pipeline infrastructure.  It would take something pretty substantial such as concrete barriers to prevent a similar intentional attack with a heavy vehicle, and there are plenty of vulnerable pipeline stations scattered around Texas and the rest of the country.  If this was simply a spectacular way for an isolated individual to commit suicide, it is likely not to be repeated any time soon, and the idea of passing regulations to make all pipeline systems proof against such attacks might be judged excessive. 

 

On the other hand, the 9/11/2001 terrorist attacks on the U. S. showed what a malevolent organization can do with people who are willing to give their lives for a cause.  In terms of casualties, the destruction caused by this particular fire was relatively small, and probably would not have appealed to a terrorist bent on causing death and destruction.  Fortunately, there was little wind during the fire, and any toxic products of the fire were carried far aloft, for the most part.  Nevertheless, it was a major inconvenience while it lasted, and if it had happened closer to a more populated area such as a school, the consequences could have been much worse. 

 

Residents of Deer Park who choose to live there or work there by and large know what they're getting into.  In an ideal world, no one would have to, let alone want to, live in a place that might be a long-term hazard to your health, coupled with a small but non-zero risk of being blown up or incinerated.  In many parts of the world, especially among professional and leadership classes, the entire array of fossil-fuel industries is something to get rid of as soon as we can. 

 

But few of the people holding those opinions have lived in a place where one's father and perhaps grandfather has made a good living from fossil-fuel-related work.  Nobody gets out alive, and during one's brief time on earth, doing something that can benefit others, even at risk to oneself, can be viewed as a good thing.  One person, for reasons known only to God now, decided that his own personal time was up, and chose to end that time in a spectacular way that ended one life and endangered others. 

 

We should do what we can to keep things like this from happening again.  But just as important is creating a cultural environment in which the average person can do remunerative work and feel that the rest of the world, or at least a good bit of it, appreciates what one does instead of wishing it would all just go away.   

 

Sources: I referred to reports on the fire at https://www.houstonpublicmedia.org/articles/news/energy-environment/2024/09/19/500356/deer-park-pipeline-fire-human-remains-suv-removed/ and https://abc13.com/post/deer-park-pipeline-blast-site-repairs-days-after-explosion-forced-residents-homes/15331135/.  The photo from space can be seen at https://www.khou.com/article/news/local/deer-park-pipeline-fire-international-space-station-photo/285-9c64b48c-b81e-48b3-aa40-ae740e057ab6.