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.