Facts, Investigations, and Rumors: The Houston Tank-Farm Fire

NOTE:  Due to an oversight, this blog was not posted last week.  It was intended to appear on Apr. 1.  My apologies in case you missed it.---KDS

As most readers of this blog know, most of what appears here is commentary on engineering-ethics-related news from other sources.  First-hand reporting is not my bag, if for no other reason that I don't have time for it, and there aren't a lot of sources who are willing to be called at 5 AM, which is usually around the time I'm writing it.  But a week or so ago I received some information almost by chance, and it puts me in something of an ethical dilemma.  Do I write about something that wasn't intended for publication or not?  Well, with certain precautions, I've decided to go ahead.

Here's the known and widely publicized facts:  On Sunday, Mar. 17, a fire began at the Intercontinental Terminals Company (ITC) tank farm in Deer Park, an industrial suburb of Houston.  It quickly spread and at one point involved 11 of the 242 tanks at the facility.  Firefighters could only spread foam on nearby tanks to keep the fire from spreading, but had to wait for the products contained in the tanks to burn away, which took several days.  These products included toluene, xylene, naphtha, and benzene, a known carcinogen.  The fire made a huge black plume visible for miles, and caused the closure of several local school districts for a day or two.  Authorities also temporarily closed a portion of the nearby Houston Channel to shipping due to the fire.

Naturally, the fire is going to be investigated.  Although no one was killed or injured as an immediate result of the fire, millions of dollars' worth of chemicals and plant facilities were destroyed, and an unknown amount of toxic chemicals was released into the air, the ground, and the water nearby.  Anything this consequential is worth investigating because of the lessons that can be learned to avoid similar accidents in the future.

An independent agency, the U. S. Chemical Safety Board, announced last week that it was opening its investigation into the accident.  This board is recognized for its thorough and reliable conduct of mishap investigations, which can take months or even years before a well-researched report is issued.  In the meantime, before such reports are available, the cause remains officially unknown, although the facts that wind up in the official report are presumably somewhere waiting to be investigated.

And in the meantime, the last thing any company official is going to do is talk loosely about what they think might have happened.  This explains the relatively small amount of information that ITC released on its own during the fire, which burned off and on for nearly a week.  Lawyers flock to major accidents like—well, I was going to mention a species of bird, but we'll just let it go at that.  Already the Texas attorney general has announced that he's suing ITC for the pollution caused by the fire, and other suits will follow as night follows the day.  And the less fodder given by a company's officials to lawyers to use against them, the better, as far as the company is concerned.

So much for officialdom.  Now for the rumors and unconfirmed reports.  I did manage to find a reference in a minor Houston news outlet (the Houston Press) to the following report:  "Also Wednesday morning, the Houston Chronicle was quoting an unidentified worker as says the fire may have been started when a tank overheated and a safety valve did not shut that down."  I was unable to locate the original Chronicle story, but (and here's my contribution to the mix), it fits in with what a friend of mine heard from his connections back in Deer Park, where he was raised and worked in the refining business for most of his career before retiring to my area.  For obvious reasons, he will remain anonymous here.

On the Friday after the fire began, he told me the following.  At a tank farm there are tanks, pipes, valves, and pumps to send the various products to nearby facilities or transportation points such as loading locations for tank cars and tank trucks.  Some of these pumps are quite large, using multiple-horsepower motors that consume many kilowatts of power.  If an order comes through to a technician to send a certain amount of product to a certain pipe, the appropriate pump is turned on first and then the valve is opened, because otherwise, unforeseen back pressure or other issues might cause products to go the wrong way and get mixed up.

But it's vitally important, especially when a large powerful pump is involved, to turn on the valve shortly after the pump is turned on.  If this isn't done, all the energy that the pump's spinning impeller puts into the liquid can't go anywhere and turns into heat.  And the product—often a flammable one such as naphtha—can get hot enough to rise past its flash point, so that once the valve is turned on and any air is present, the product will spontaneously catch fire.

Normally there are thermal cutout sensors that will detect when a pump's outlet overheats due to misguided operation such as this, and shut off the pump automatically.  But sensors sometimes fail.

What my friend heard was that someone turned on a pump in preparation for shipping some flammable product out of the plant, but due to paperwork or some other delay, the appropriate valve wasn't turned on for some 17 hours.  That's plenty of time for a pump without a safety thermal cutout to get its product way too hot.  And so sometime Sunday, the product caught fire, and the rest is very public history. 

Distorted through a rumor mill and two news outlets, that more detailed story fits in with the unconfirmed and unattributed report that a "tank overheated" and a "safety valve" (read: thermal cutout) did not shut it down.  So strictly speaking, I'm not reporting a scoop here.  But it does sound like confirmation of another unattributed report.

Whatever the rumors say, we'll have to wait for the Chemical Safety Board to interview everyone concerned, compile the data they can obtain from SCADA (supervisory control and data acquisition) digital records, and anything else they find that's relevant to getting to the bottom of this accident officially.  But in the meantime, plant operators everywhere should pay extra attention to pumps and valves and timing.

Sources:  Besides my friend, I consulted the report on the fire carried by Chemical and Engineering News at https://cen.acs.org/safety/industrial-safety/Houston-chemical-distribution-tank-farm/97/web/2019/03 and found the unattributed report of the overheated tank at https://www.houstonpress.com/news/itc-tank-fire-extinguished-but-some-school-remain-closed-11258138. 

West One Year Later: Will It Happen Again?

On April 22, the U. S. Chemical Safety Board held a news conference to present its recommendations about how to prevent another disaster such as the one in West, Texas that killed fifteen, injured over 200, and caused millions of dollars of property damage on April 17, 2013.  So far, not a lot has changed in terms of federal or state regulations pertaining to ammonium nitrate, the fertilizer chemical that exploded on that fateful day.  But a fertilizer trade organization has issued a set of recommendations that, if followed, will go some distance toward reducing the chances that another disastrous accident involving the chemical will happen again.

As long ago as 2002, the Chemical Safety Board recommended that ammonium nitrate be included in OSHA (Occupational Safety and Health Administration) and EPA (Environmental Protection Administration) regulatory programs, but these agencies have not yet chosen to act on these recommendations.  Ammonium nitrate falls in a gray area between chemicals such as nitroglycerin or TNT that are clearly dangerous, and others such as sand that are harmless.  Under most circumstances, ammonium nitrate can be handled with little or no risk.  But under certain combinations of heat, pressure, and/or shock, the chemical detonates, transforming many tons of solid matter into hot gases that expand explosively, as they did in West. 

In response to the West accident a trade organization called The Fertilizer Institute issued a fourteen-page booklet to its members last February with the title "Safety and Security Guidelines for the Storage and Transportation of Fertilizer Grade Ammonium Nitrate at Fertilizer Retail Facilities."  The title does not promise exciting reading, though the legalese and lengthy definitions of different types of ammonium-nitrate fertilizer are enlivened by color photos of fertilizer manufacturing and handling installations.  The pamphlet summarizes most of the precautions which, if followed, would have gone a long way toward preventing the West disaster. 

These measures fall into two categories: (1) ways to prevent ammonium nitrate from exploding in the first place, and (2) ways to avert death and destruction if a fire breaks out where ammonium nitrate is stored, and the stuff explodes anyway.  The prevention measures are more or less what you'd expect:  things like storing the material in non-combustible bins, rather than wooden ones as were used in the West firm; installing sprinkler systems or other fire-prevention and fire-fighting facilities; and treating places where ammonium nitrate is stored like flammable-material storage areas (no-smoking signs, no sparks or flames nearby, etc.).  Because an exact cause of the fire at West that led to the explosion may never be found, we cannot know for certain if these precautions would have prevented the tragedy.  But obviously, they are good things to do, and if fertilizer retailers around the country follow these prevention guidelines, the chances of another such accident will be reduced.

The second category of recommendations is more problematic.  It involves informing the wider community, including first-responder agencies, that ammonium nitrate is stored in the facility and should be treated with extra caution.  By the nature of the business, many fertilizer retailers are located in semi-rural or thinly populated areas.  These locales are often served by volunteer fire departments, and while volunteer firemen theoretically should be trained as well as full-time paid firefighters, the reality is that their training may be on the sketchy side.   The Chemical Safety Board concluded that the first responders in West did not know of the dangers presented by the large quantity of ammonium nitrate stored at the plant where they responded to what appeared at first to be an ordinary fire, and were much too close for safety.  Consequently, when the plant exploded, most of the people who died were firefighters.  The guidance handbook says "The rule of thumb is if outside emergency responders are necessary, do not fight AN [ammonium nitrate] fires.  For fires that have engaged AN, plans should focus on evacuation of the area."  In other words: don't fight, run. 

While the trade-association brochure's advice is good, it has no legal standing, and firms are free to adopt its recommendations or ignore them.  Simply as a matter of asset protection, I would hope that fertilizer retailers who sell ammonium nitrate are at least considering an upgrade of unsafe storage facilities, and the brochure provides good guidelines as to how to carry this out.  However, the informational side of the recommendations may be harder to implement.  A business owner may feel some reluctance in volunteering the information to local authorities that his facility harbors material that might reduce a wide swath of his neighborhood to rubble.  Nevertheless, there may be courageous and conscientious owners who will do such things. 

Both the Chemical Safety Board and various other authorities have called for tighter compulsory regulation of ammonium nitrate storage and transportation.  This is a political as well as a technical and ethical matter, and politics these days tends to go to polarized extremes.  On the one hand are those who favor centralized uniform federal regulations for all sorts of things, including ammonium nitrate.  On the other hand, a prominent plank in the Tea Party platform is the idea that government regulations have gone too far and are stifling free enterprise and economic growth.  The regulations contemplated with regard to ammonium nitrate vary from rules about how the stuff is stored to rules about notification and training of local first responders.  It seems to me that sensible regulations requiring the exchange of information, perhaps implemented by some sort of web-based registry, would be the least costly way to make sure that at a minimum, any firefighters responding to an ammonium-nitrate fire would know what they are dealing with and would take appropriate precautions. 

One way of dealing with this information problem is by the use of fire codes.  However, the state of Texas has a strong history of anti-regulatory bias.  In fact, counties with low population density in Texas are actually prohibited by state law from enacting fire codes at all.  So around July and December, you see roadside fireworks stands popping up for a few weeks with nary a concern for any safety beyond the immediate self-preservation of the owners in case a customer drops a burning cigarette. 

So far, the only concrete public action toward preventing more ammonium-nitrate fertilizer disasters has been the Fertilizer Institute's brochure.  While they deserve credit for their efforts, only time will tell whether enough has changed to keep another fertilizer plant from blowing up, or to save lives if it does.

Sources:  The news conference in Dallas on Apr. 22, 2014 held by the Chemical Safety Board was summarized by a UPI report at http://www.upi.com/Top_News/US/2014/04/22/US-investigators-Better-regulation-could-have-prevented-deadly-fertilizer-explosion/4731398190424/.  The Chemical Safety Board's own statements at the conference can be downloaded at http://www.csb.gov/assets/1/16/Statement_-_News_Conference_(Final).pdf.  The Fertilizer Institute recommendations can be found at http://www.tfi.org/ammonium_nitrate_guidelines.  And I blogged on the West explosion previously on Apr. 22 and May 20, 2013.

What We Don't Know About Chemical Accidents

The fertilizer-plant explosion last April 17 in West, Texas that killed 15 and demolished a good part of the town was only the most recent of a number of accidents involving hazardous chemicals that have happened in Texas over the years.  Home to a large number of refining and petrochemical plants and other high-tech industries, Texas has had more of its share of explosions, fires, releases of toxic and polluting chemicals, and other chemical-related accidents.  But when a team of Dallas Morning News reporters tried to answer what they thought was a simple, straightforward question about the frequency of chemical accidents, they found a mare's nest of conflicting and incomplete statistics.  Is this a basic problem that leads to a higher rate of accidents than we would otherwise have?  Or is it just an inherent difficulty that comes about because of the nature of chemical accidents?

The News reporters were unable to find a single database of national scope that answered the question they were asking.  I think what they wanted to find was something like what the U. S. Center for Disease Control (CDC) maintains on statistics such as cases of measles or rabies, or the National Transportation Safety Board's database on fatal accidents involving air transport.  But what they found instead was a hodgepodge of things:  raw unfiltered lists of emergency calls to the U. S. Coast Guard, lists of incidents investigated by the Occupational Safety and Health Administration (OSHA), and data collected by the Chemical Safety Board, which relies primarily on media reports—in other words, the reporters themselves!  They found glaring inconsistencies among the numbers cited by the various sources of information, and although they were able to identify 24 potentially serious chemical accidents in Texas between 2008 and 2011, they were almost sure that the true number was higher.

The first question in compiling statistics on something is to define exactly what you are compiling statistics on.  The problem of defining a chemical accident is not a trivial one.  Clearly, if I'm working in my garage and accidentally knock over a can of used oil that spills into the ground, that is not something that should be treated with the same seriousness as the West explosion.  But by some definitions, both are chemical accidents.  So first, a line needs to be drawn defining how serious an accident should be before it is logged into a database.  But how do you draw that line?  Should you log only accidents that resulted in casualties (deaths or injury to persons), or a minimum amount of property damage, or all accidents that involve certain types of particularly hazardous chemicals?  There are millions of kinds of chemicals, and the hazard to humans of many of them are simply unknown. 

Even if we agree that casualty-only accidents are what we want, the problems of privacy and legal liability come into play. As noted by the Dallas Morning News reporters, private firms are reluctant to share details of their inner workings that might leave them open to lawsuits or might prove repellent to potential investors.  As the aftermath of the West explosion has shown, the legal environment of chemical accidents is complex, poorly defined, and is the result of a tangle of criminal, regulatory, and civil codes that do not produce the kind of clear-cut situations that are easy to record in databases.

Not mentioned by the investigative reporters is a powerful external force on chemical industries which makes most firms maintain and enforce strict internal safety rules and records of accidents.  This force is applied by insurance companies.  My brother-in-law is the chief safety officer for a large firm that operates refineries in several states.  One of his main jobs is to travel to the home offices of the company's main insurers annually, and present detailed reports of his firm's safety records and the measures they are taking to make sure lessons are learned from near-misses in order to prevent bigger accidents in the future.  While these matters are handled out of the public eye, the desire to keep insured is one reason that the chemical industry as a whole has a safety record that is much better than it could be, considering the millions of pounds of hazardous material that passes through its facilities every year.  And in conversations with my brother-in-law, I have learned that firms quickly learn about accidents at other firms, and take steps to make sure those types of incidents don't happen to them too.  In other words, a good bit of what a comprehensive nationwide database of chemical accident reports would do, is already taking place: namely, information-sharing among the plant operators themselves.

Of course, there are always exceptions, which often tend to be among the smaller independent operators that can't afford full-time safety officers and large staffs.  The West fertilizer plant was one such operation, but it is not clear that having an accurate national database of fertilizer-plant explosions would have made much difference in the way that particular accident transpired. 

More and better publicly accessible information about chemical accidents is a desirable thing, and I hope that the West explosion will lead to a better system of gathering and presenting such data nationwide.  But if this goal is achieved at the cost of burdensome, onerous, and unjustly harsh regulations of industries which already do a fairly good job of self-policing due to the economic interests of their insurers, the price tag may be more than we should pay.

Sources: The Dallas Morning News report appeared on that paper's website on Aug. 24-25 at http://www.dallasnews.com/news/west-explosion/headlines/20130824-after-west-disaster-news-study-finds-u.s.-chemical-safety-data-wrong-about-90-percent.ece.

Update on West: Causes and Consequences

Last Thursday, May 16, officials from the Fire Marshal’s Office of Texas and the federal Bureau of Alcohol, Tobacco, Firearms, and Explosives announced that the cause of the April 17 fertilizer-plant explosion in the town of West was “undetermined.”  However, they had eliminated a number of possible causes and narrowed the probable ones to three:  something to do with the 120-V electrical system in the plant, a golf cart stored in the same room with the ammonium nitrate bins, and arson. 

Considering the horrible jumble of wreckage that the explosion left behind, even this much progress in the investigation is laudable.  The investigators did determine that about 28 to 34 tons of ammonium nitrate, a fertilizer ingredient, exploded in the blast that dug a crater ten feet deep and 93 feet wide and caused seismometers to register the equivalent of a 2.1-magnitude earthquake.  It could have been worse:  another 140 tons of the material stored either onsite or in railcars at a nearby siding did not explode. 

The investigation revealed that the ammonium nitrate that exploded was stored in wooden bins next to bins of flammable seeds.  No sprinkler system was in place, and under current fire-code regulations none was required in the industrial facility. 

The reconstructed sequence of events is fairly brief.  At 7:29 PM on the evening of April 17, a fire was reported at the facility.  Unless there were personnel on site that late in the evening, it is likely that no one was present at the time and the first report was turned in only after smoke was visible outside the plant.  So the fire may have had some time to get going before it was reported.  This is significant, because when ammonium nitrate is heated, it can turn from a white powder into a solid mass that transmits shock waves well.

Nine minutes after the fire was reported, firefighters arrived and began to play water on the blaze, which the investigation stated did not contribute to the explosion.  Investigators speculated that as the fire progressed, a piece of heavy equipment might have come loose and fallen onto the now-solidified mass of ammonium nitrate, causing a detonation wave that led to two almost simultaneous explosions, 22 minutes after the fire was reported.  It was these explosions that killed fifteen people, most of them firefighters, and laid waste to 37 blocks of the small town. 

Not involved in the news conference at which these findings were announced, were members of the federal Chemical Safety Board (CSB), an agency charged with investigating chemical accidents with a view toward making recommendations about how to avoid them in the future.  A Dallas Morning News reporter interviewed members of the Board involved in the West investigation, and their work is still continuing.  Rather than focusing on the narrow question of exact causes, the CSB is examining the broader picture of how regulations affected the outcome of the incident and how community responses could have been improved.  Questions have been raised, for example, about the wisdom of storing so much explosive material literally across the street from an apartment complex, and not much farther from a school and a nursing home.  Any time a fire occurs at a facility where large amounts of ammonium nitrate are stored, prudence would dictate that at a minimum, the area within a possible explosion range should be evacuated. 

On July 30, 2009, a fire at a fertilizer plant in Bryan, Texas where large quantities of ammonium nitrate were stored led to the evacuation of thousands of residents of that college town (home to Texas A&M) as a precaution.  Fortunately, the fire burned itself out without incident and no damage outside the plant resulted.  But as the West explosion shows, things could have turned out very differently.  The Bryan incident also differs from West in that the people who accidentally started the fire were the ones who reported it promptly, giving more warning than otherwise.

While regulation is always a two-edged sword that can cause more harm than it alleviates, the West explosion will at least inspire re-examination of the whole complex of federal, state, and local laws, as well as insurance-company practices, that bear on the storage of ammonium-nitrate fertilizer.  Determining the appropriate level of regulation, as well as the appropriate agency or agencies to issue regulations, is not an easy task.  Local officials, especially in smaller towns such as West, rarely have the expertise to come up with customized, science-based regulations about hazardous materials that do not cause problems most of the time.  But federal regulations are a blunt instrument, and customarily matters such as fire codes are left to the states and local communities to decide on.  National organizations such as the National Fire Protection Association (NFPA) issue model guidelines and codes, but it is a state or local option as to whether these codes are made part of local laws. 

The deaths in the West explosion were preventable, and I for one hope that the memory of this tragedy will lodge in the minds of firefighters, code-enforcement officials, and governmental agencies who are in a position to keep such things from happening, or at least lower the chances of them happening, in the future.  The sharing of basic information and knowledge about how much of what stuff is stored where needs to be mandated so that first responders know both what they are dealing with and what is prudent to do in a given situation.  Firefighting is a hazardous job, and loss of life in the line of duty is one of the risks that firefighters take on when they join their companies.  But if better information and procedures, even if mandated by the federal government, will keep both firefighters and their communities safer in situations such as what happened in West last month, it may be time to change the way things are done.

Sources:  I referred to an article on the West investigation news conference published on the Dallas Morning News website on May 18 at http://www.dallasnews.com/news/west-explosion/headlines/20130518-in-west-investigators-focus-shifts-from-explosions-cause-to-closing-safety-gaps.ece.  I also used an article from the KRHD-TV website for information on the Bryan, Texas evacuation, found at http://www.abc40.com/story/10823244/ammonium-nitrate-fire-forces-mass-evacuation.