The Pemex Vinyl Chloride Plant Explosion

Unless you work in the petrochemical industry, you have probably never been near the substance called vinyl chloride.  It is a chlorinated hydrocarbon that is made when one of the four hydrogen atoms in the compound called ethylene is replaced by a chlorine atom.  On the other hand, unless you live in a house whose plumbing is all more than forty or so years old, you probably use products made with vinyl chloride every day.  Polyvinylchloride (PVC) pipes are used in the plumbing of nearly all new residential and business construction, and about 40 million metric tons (units of 1,000 kg) of PVC plastic were made in 2013.  But all PVC pipes were once the toxic, flammable liquid called vinyl chloride, and that is what may have got loose at the Pemex chlorinate 3 plant in the Gulf Coast city of Coatzacoalcos, Mexico last Wednesday, Apr. 20.  The resulting explosion and fire killed at least 28 people and injured over a hundred, with more still missing as of today.

Besides the immediate human tragedy, this accident raises important questions about the safety record of the state-owned petroleum company Pemex.

At this writing, little is known about the cause of the blast.  Coatzacoalcos is a town at the very southernmost tip of the Gulf of Mexico, in the Mexican state of Veracruz between central Mexico and the Yucatan Peninsula.  It is one of the main export terminals for Mexican oil and is a logical location for a vinyl-chloride plant, since its manufacture requires large quantities of the petrochemical ethylene.  The chlorinate 3 plant is a joint venture between Pemex and a PVC-pipe manufacturer called Mexichem. 

As with many petrochemicals, vinyl chloride is hazardous in several ways.  If released into the air, it evaporates into a dense vapor and can catch fire if a source of ignition such as an automobile engine is nearby.  Worse yet, the products of combustion are themselves hazardous:  hydrogen chloride (which when dissolved in water makes hydrochloric acid), and phosgene, which was used as a poison gas in World War I.  Besides the danger of explosion and fire, vinyl chloride is extremely toxic, and causes liver damage in animals at concentrations in air as low as 500 parts per million.  Higher concentrations cause acute illness and even death.  Because of these hazards, vinyl chloride is usually stored in double-walled containers under pressure, with leak monitors that detect low levels of leakage from the inner container before the outer wall is breached. 

It may take months before we can learn exactly what happened at Coatzacoalcos, but it is obvious that a large amount of something flammable got loose.  Some reports mention a strong odor of ammonia, which could be from refrigeration machinery used in process cooling operations in the plant.  Whether or not vinyl chloride itself was released, the high death toll says several things about this accident.

First, one can ask why there were so many people in a hazardous area.  The trend in modern petrochemical operations is to reduce staffing to the point that in emergencies or during strikes, an entire plant can be operated safely from one central control room.  Although this is speculation, it is possible that Pemex, being owned by the Mexican government, has adopted a different policy and relies more on hands-on operators in its plants as a way of increasing government-paid employment.  Whatever the reason, Pemex's safety record is not good.  News reports of this accident relate that in 2012, 26 people were killed in a natural-gas facility owned by Pemex and in 2013, an explosion in Pemex's Mexico City facilities killed 37 people. 

Next, what kind of safety culture does Pemex have?  To run a complex petrochemical plant without accidents is a monumental task, and many safety priorities are expensive, in the sense that they take resources which otherwise could be used to enlarge the firm's bottom line.  With the recent crash in oil prices, there are reports that Pemex is cutting expenses, and this latest accident raises the question of whether safety has been sacrificed to budget considerations.

Finally, there is Pemex's status as a state-owned enterprise.  I am not familiar with Mexican law, but it is quite possible that it is either statutorily or practically difficult to sue Pemex.  Also, Pemex may be self-insured rather than purchasing hazard insurance on the open market.  Both of these factors, if true, remove two of the greatest incentives private firms have to run their operations safely:  fear of lawsuits from injured parties and financial pressure from private insurers to run a safe and low-claims operation.  Without such incentives, Pemex management has only its own integrity to rely on for worker safety, and the demands for sustaining profits in the face of falling oil prices may have overwhelmed safety concerns. 

I hope that the investigative bodies in Mexico have all the competence and authority they need, not only to get to the bottom of this tragedy, but to publicize its causes and assign responsibility wherever it needs to be assigned.  Again, the status of Pemex as a state-owned firm may lead to conflicts of interest between state officials who want to make workplaces safer, and other officials who do not want to see a state-owned enterprise called to account.  The loser in such a conflict will be the workers who have the choice of being paid to put their lives on the line in a hazardous workplace, or to go somewhere else and earn even less than the $12,000 US annual salary that was the average in 2005 for Mexican chemical engineers. 

If reports surface in English as to the cause of this accident, it will be interesting to learn whether poor safety practices contributed to it.  In the meantime, my sympathy goes to all of those who lost loved ones or were injured.  And I hope this latest incident leads to a re-evaluation of the entire safety culture of Pemex, which looks like it could use a lot of work.

Sources:  I referred to a Reuters report on the accident at http://www.reuters.com/article/us-mexico-pemex-idUSKCN0XH2N2, an ABC News report at http://abcnews.go.com/International/wireStory/death-toll-28-mexico-petrochemical-plant-explosion-38614458, a Fox News item at http://www.foxnews.com/world/2016/04/21/blast-at-mexico-petrochemical-plant-kills-3-injures-more-than-100.html, and a CNN report at http://www.cnn.com/2016/04/23/americas/mexico-pemex-petrochemical-blast/.  I also referred to statistics on PVC production at http://www.plasticstoday.com/study-global-pvc-demand-grow-32-annually-through-2021/196257501821043, a salary survey for Mexico at http://www.worldsalaries.org/mexico.shtml, and the Wikipedia articles on vinyl chloride and ethylene. 

A Tech Fix for Texting While Driving

By now, almost everybody with a cellphone and a car knows that it's a bad idea to text while you're driving.  But people still do it, and some of those people die in text-related car crashes and take innocent victims with them.  What if technology existed that simply prevented people from texting from a moving car at all?  Wouldn't that solve the problem?

Scott Tibbetts thought so.  Tibbets and his company Katasi were profiled in a recent New York Times article for developing a promising technology that would simply block texting from any phone that was in a moving car.  While there are several technological solutions to this problem that are already on the market, they all have various problems. 

Some text-blocking apps work by using the phone's GPS to figure out if the phone is moving faster than walking speed.  If it is, the software concludes that you're driving, and blocks texts.  This one turns out to be a battery hog, because the GPS system has to run all the time.  It also might present problems for train and bus passengers.  Another system uses the car's speed sensor and links it to the phone with a Bluetooth wireless connection.  But it costs over a hundred bucks, and there aren't that many people who are both concerned enough about texting while driving to buy it, and also willing to shell out that much money for something they could do for free with a little more willpower, perhaps. 

Mr. Tibbetts' solution is cleverer than these.  It involves connecting a wireless box to the car's OBD-II port—the on-board diagnostics socket that the auto technicians use to figure out what the "service engine" light means.  When the car's moving fast enough to be dangerous, the wireless box sends that information to the cellphone network, which then asks the phone—once—where it is.  Then, if the network is using the software developed by Mr. Tibbetts' firm Katasi, the software uses the location data to figure out things like who is driving the car.  You don't want a whole family's text service blocked just because Mom is driving to the grocery store, for instance.  That way, the GPS battery-drain problem is minimized, and the computational heavy lifting is done in the cloud, so to speak, rather than by the phone.

Mr. Tibbetts, an aerospace engineer and entrepreneur, has persuaded both an insurance company and a cellphone provider (Sprint) to cooperate in test trials, which have worked fine.  But it appears that the largest player, Sprint, has gotten cold feet lately, and has stalled further tests.  In the Times interview, Wayne Ward, vice-president for business and product development at Sprint, expressed concerns about product liability.  Currently, if a driver texts while driving and gets in a wreck, it's the driver's fault.  Mr. Ward asks what might happen if Sprint sells the Katasi system that claims to prevent such accidents, and then some glitch happens and somebody sneaks through a text and crashes anyway?  Why, Sprint could be sued!

Pardon me, but it appears that there's more going on here than meets the eye.  Any time a small independent company comes up to a big firm and offers the big guy new technology, the not-invented-here problem can raise its ugly head.  Short of buying the small upstart outright (which happens a lot, by the way), if the big firm adapts the small company's technology, they will be on the hook for royalty payments or other forms of obligation that big companies don't want to be tied down to.  And there's also the simple pride factor expressed by the phrase "not invented here"—if we didn't think of it first, it can't be that good. 

Besides, it's not clear who would make enough money to offset the expenses of the added hardware and software—and lawyers' fees, if Mr. Ward's fears turned out to be correct.  The existing GPS-based solutions for text blocking in cars aren't exactly selling like hotcakes, even after all but five states have adopted no-texting-while-driving laws of one form or another. 

One could imagine a legal solution:  make something like the Katasi text-blocking system mandatory by government fiat.  Nobody has seriously put forward that idea yet.  But it might happen.  There was a time when ordinary window glass was used in automobiles, with the result that otherwise minor wrecks turned deadly when razor-sharp knives of glass flew around and sliced—well, enough said.  But when the technology of laminating glass with a plastic inner layer was developed around 1920 to keep the shattered pieces together, auto companies adopted it, partly motivated by fear of lawsuits.  Eventually, most countries made it a legal requirement for all glass in automobiles to be laminated or safety glass, but it looks like the firms were ahead of the government in that case.

Safety glass is a different kind of thing than automatic text-blocking.  An auto company could start using safety glass and just raise the car's price incrementally, and hardly any customers would notice the change.  But as soon as you stop a person from doing something that they're used to doing, like texting while driving, you create a sharp negative impression.  And that's something that cellphone providers are reluctant to do as long as there are competitors ready to take business away.

My hat is off to Mr. Tibbetts, who put five years and millions of dollars into developing a clever technological fix for a significant problem.  But as many engineers turned entrepreneurs have learned, building the better mousetrap­—or text trap—is only part of the problem.  Convincing people to buy it and use it is often harder than coming up with the invention itself.  If everybody used something like the Katasi system on their cellphones, we would all be safer, no question about that.  We would also lose a little freedom of judgment which we can now exercise, which is whether to text while driving.  Perhaps some telecomm industry leaders will get together and agree to adopt Katasi, or something like it, but such inter-company cooperation for a non-financial thing like safety is a rarity.  It could happen, though.  I bet Mr. Tibbetts, for one, hopes that it will. 

Sources:  The New York Times article "Trying to Hit the Brake on Texting While Driving" by Matt Richtel, appeared in the online edition on Sept. 13, 2014 at http://www.nytimes.com/2014/09/14/business/trying-to-hit-the-brake-on-texting-while-driving.html.  I also referred to Wikipedia articles on on-board diagnostics, windshields, and safety glass. 

Do You Smell Gas? Thank New London

On Thursday, March 18, 1937, a seventh-grade girl named Sibyl sat in a school bus outside the junior-senior high school building built four years earlier in the unincorporated town of New London, Texas.  In contrast to the rest of the nation, New London and the surrounding area of East Texas were prospering from a local oil boom, and many of the school's students came from families drawn to the area by oil-field jobs.  Sibyl had mistakenly left her class early, but rather than go back inside and look foolish, she had decided just to wait in the bus until school let out for the day in another twenty minutes or so.  Suddenly, at 3:17 PM, she saw the entire front of the building rise several feet into the air and then collapse into a huge pile of dust with a thunderous crash.  She had just narrowly escaped what turned out to be the worst school disaster in the history of the United States.  Over three hundred children and adults died either in the explosion itself or as a result of injuries they sustained in it.  The cause?  Odorless natural gas.

As you may know, natural gas has no characteristic odor of its own.  By law, a malodorant must be added to natural gas for non-industrial users such as homes, businesses, and schools so that a leak will call attention to itself by means of smell.  One of the compounds used, butyl mercaptan, is so stinky that the average human nose detects it at a level of 0.33 parts per billion.  That concentration amounts to one teaspoon of malodorant in a cube of air about 25 meters (80 feet) on a side.  While gas leaks and explosions still occur, the chances of detecting a leak before it causes an explosion are much better when the gas contains a malodorant. 

Flammable gas has been used for domestic light and heat since the early 1800s, but until the discovery of large supplies of natural gas, piped-in gas was a relatively costly type of utility that was confined to cities.  By contrast, the oil wells around New London freely produced so much natural gas that it was (and still often is) considered a waste product, and was flared off near wells in towering flames that burned day and night and could be seen for miles.  The oil companies piped some of it around in what were called bleed-off lines to supply power for their own operations, and because many of New London's residents were already familiar with oilfield equipment and piping, tapping a nearby gas line for free raw natural gas became a common practice.  Although it was technically illegal, someone with the requisite skills could install his own private gas line to an oil lease's bleed-off line, and enjoy free gas instead of paying the local gas utility for it. 

It is a matter of record that a couple of months before the 1937 explosion, W. C. Shaw, superintendent of the New London schools, authorized a janitor to disconnect the schoolhouse from the local gas utility and tap a nearby bleed-off line instead.  Mr. Shaw apparently viewed this as a cost-saving measure, similar to the earlier decision when the school was built to forego the usual steam-boiler-radiator heating system, and instead install an extensive gas piping system and some seventy gas space heaters instead. 

In My Boys and Girls Are in There, a recent book on the tragedy, historian Ron Rozelle notes that many subsequent summaries of the disaster tend to blame Superintendent Shaw for endangering the lives of his charges with the decision to use free untreated bleed-off gas.  The critical question, which Mr. Rozelle doesn't answer in the book, is whether the local gas company was adding malodorant to its product at the time.  Such a practice was widespread by 1937, but by no means universal.  If the utility's gas was odorless as well, then the decision to switch to bleed-off gas made no difference, because the leak that caused the explosion would not have been any easier to detect.  The main reason that the explosion was so severe and extensive was that the poured-concrete school building had a single, poorly ventilated, and uninterrupted crawl space beneath the entire front part of the building, under eight inches of solid concrete floor.  Since natural gas (primarily methane) is lighter than air, this crawl space formed a good container for thousands of cubic feet of gas, which was touched off on that fatal day when a shop teacher switched on an electric sander in the basement. 

While the New London explosion dominated national news for a week or so, it faded quickly as other events diverted the public's attention.  Like war veterans often do, survivors of the explosion usually refused to talk about it afterwards.  However, one survivor, fifth-grader Carolyn Jones, had the courage to make a speech to the Texas House and Senate in Austin only a week after the explosion, urging that safety measures be passed to prevent another disaster like the one at New London.  The result?  Two laws:  one requiring all natural gas for domestic purposes to contain a malodorant, and the other requiring that anyone working on residential natural-gas lines for residential use must be trained and certified for such work by the state of Texas.  The publicity of the New London disaster furnished ammunition for the passage of similar laws in other states, so that eventually, all natural gas sold for household use would carry its own portable detection system, namely, a bad smell.

The New London explosion and its aftermath form a familiar pattern:  first an innovation (the use of natural gas for domestic gas supplies was fairly new in the 1930s); then a tragedy resulting from inadequate safeguards, ignorance, or other factors; then regulations, or a change in good engineering practices, or both, all inspired by the tragedy.  It would be nice if engineers were able to anticipate everything that could go wrong in a novel situation.  But human ingenuity being both fallible and limited, sometimes we have to learn from mistakes, and the more costly the mistake in terms of lives, the faster we learn.  While nothing will ever bring back those three hundred lives lost on that East Texas afternoon seventy-six years ago, it is some comfort to know that their lives were not lost in vain, and that gas users around the globe are safer as a result. 

Sources:  I thank Andrea Nelson and Stephen Paul for bringing my attention to Ron Rozelle's book My Boys and Girls Are in There (College Station:  Texas A&M University Press, 2012), which I relied on for most of the material in today's column.  I also referred to the Wikipedia articles on the history of manufactured gas, thiols, and tert-butylthiol.