Industrial catastrophes are not very frequent events but are more common than many would
like, and every decade has had a multitude of shocking disasters.
The 1980’s was no exception and definitely had more than its fair share, like for example
the well known ones in the form of chernobyl, Piper Alpha and bhopal to name a few.
These are the ones that are so devastating that the ramifications of such events have
traveled well beyond the borders of the country of origin.
But what I personally find more worrying are the smaller localized events, the ones that
are often not reported across the globe, getting forgotten to time.
These disasters are the ones caused by seemingly mundane reasons such as incorrect routine
maintenance, on the face of it minor adjustments to procedures or just a failure to check things
properly.
An explosion in the chemical facility can easily become part of the white noise background
of the daily news cycle, and in some regards allow the events to be downplayed.
The disaster would rack up a death toll of 23 employees injuring 314, and the company
in charge would get a modest 5$ million dollar fine, even though safety on site was inadequately
managed.
As such today's subject will get a rating of 7 on my plainly difficult disaster scale,
and also a 7 on the historical legacy scale as the event helped improve process safety.
Welcome to A brief history of the 1989 Phillips Petroleum Chemical Plant Explosion and Fire
in Pasadena, Texas.
Phillips petroleum was a petrochemical company with its history tracing all the way back
to 1917 with the forming of the company by brothers Lee Eldas ("L.E.") Phillips and Frank
Phillips, based out of oklahoma.
Quickly the company worked in all parts of the oil industry including fuel production,
crude oil pipelines, refineries, and marketing of petroleum products.
Like many companies during this period the demand for fuel boosted the organisations
coffers, but the growth would really speed up during the big old dumpster fire that was
the 2nd world war.
By the late 1940s the ever growing Phillips petroleum had become active in the chemical
business, creating the Phillips Chemical Company, which set up and began operating a large plant
on the Houston Ship Channel.
In the 1950s the plant began producing a polyolefin plastic trademarked as Marlex, this was used
in blow moulded or rotationally moulded components.
It would be this facility that we will be focusing on today and would be the epicenter
for disaster nearly 40 years after it began operation.
By the 1980s the site was being used to produce polyethylene which is one of the most common
plastics used in bags food packaging and pretty much anything you use day to day!
Making this material can be a dangerous process as highly flammable gasses are given off which
would be the cause for disaster, but first let's look at the process used by Phillips
chemical. High-density polyethylene is manufactured
at Plants IV and V at the Houston Chemical Complex (HCC) at high temperature and pressure.
The process uses a thing called a loop reactor, which is an arrangement of 30-in.-diameter
pipes mounted vertically in 150-ft-tall, continuous circular shaped structures, this heats and
pressurizes a chemical mixture to 600 psi (4,100 kPa) and .
The reaction is one of condensation polymerization of about 95% ethylene dissolved in isobutane,
Hydrogen and hexene were also added to achieve targeted product quality specifications.
As the reaction product gained mass in the loop reactor, it would eventually become heavy
enough to drop out of the circulating reaction mixture.
At the bottom of the loop reactor were setting legs, 6 in total, and 8ft long, that are used
for collecting the polyethylene particles. Each leg had two valves one at the top and
one at the bottom, the upper consisted of an air operated 8” ball, these were used
to isolate the section from the reactor after production.
The bottom valves were take off ones that were fed to a flash tank.
Once a leg was full or clogged with product the 8” ball valve would be closed, this
was to stop the highly flammable gasses inside the reactor from venting to the atmosphere.
The settling legs were the interface between the high-pressure reactor)and low-pressure
flash tank process sections; once the process was complete the polyethylene fluff was then
taken from the tank to be turned into the finished product.
But the way the reactor and setting legs were designed to work had a problem, and that was
everything had to be shut down once all 6 became full or clogged.
This necessitated the need to be able to empty the legs during full power production, to
reduce downtime. Phillips Petroleum had a policy for safe equipment
isolation, meaning any maintenance would have to have backup isolation called double blocking,
this can be done by a double valve setup. Obviously this would only work if the area
you want to isolate had two valves, if this wasn't possible then a bolted flange set up
could be used to have 2 levels of protection. This had in the case of the loop reactors
a problem, that installing a blind flange was time consuming, making maintenance whilst
the reactor was running pointless. So as we see often in these videos, a local
solution was devised. This involved The 8-in. ball valve being closed to isolate the plugged
settling leg from the loop reactor. Then the 8-in ball valve stem was physically
locked in its closed position. Finally the inlet and outlet air hoses actuating
the 8-in. ball valves were disconnected from the remote valve switch control panel.
This was double locked but definitely not double blocked, as any failure of the ball
valve could mean the reactor was exposed. After this locking was complete the setting
leg could then be emptied by removing the release valve and having a contractor reach
their arm up the leg to pull out the fluff. This might sound a reasonable form of protection,
but even though the valve was double locked it there was still a possibility to move leaving
no secondary protection. This leads us to October 22, 1989 Three of
the six settling legs on Reactor 6 in Plant 5 were plugged.
As had been done before during production Operations personnel isolated the settling
legs according to the alternative isolation procedure, closing the 8-in. ball valves,
locking them and disconnecting the air hoses. The first was disassembled and had its fluff
removed relatively easily by the contractor, this happened whilst the reactor was still
in operation. The crew wouldnt tackle the second leg until
the next day, when the contractor attempted to remove the blocked fluff only ¾ was set
fee leaving the leg partially blocked. The morning hadnt gone to plan but the contactor
attempted to get out the remaining material around lunch time. analysis
At some point the air hoses to the valve had been reconnected and the lockout device was
not properly installed, somehow the valve opened releasing the highly flammable gasses
out of the reactor into the air. At around 1pm, the reactor lost its entire
contents of more than 85,000 lb of the highly flammable process materials, the escaping
chemicals then ignited. The explosion created a force equivalent to
2.4 tons of TNT, registering as a 3.5-magnitude earthquake on the Richter scale.
Several other explosions were felt as chemicals stored onsite also ignighted.
23 people where killed and 314 were injured, the fire raged at the 14 sotrey high site,
first response was provided by the Phillips Petroleum Company contractor fire brigade
which was soon joined by members of the Channel Industries Mutual Aid association.
Cooling water from fire apparatus was trained onto the area of the fires, but the intensity
and fuel load were such that the responders were only able to contain the fire.
The efforts were hindered by low water pressure caused by pipe rupturing during the explosion.
Eventually control of the fire was achieved by approximately 1900 hours although smaller
blazes continued throughout the night. Rescue and recovery of the explosions victims
was severely hindred during the fire, and after it had been extinguish due to fears
of structural collapse. A 1 mile no fly zone was set up around the
site to prevent any of the site being distubed by aircraft downwash.
With a heavily damaged site reaching a cost reported to be over 700 million dollas, a
question is left how? Well investigators quickly found that the
valve had been improperly locked out, but alot of guess work is left as to why.
This is because the operators working at the reactor were killed in the explosion, it shouldnt
really have happened as the process for locking the valve was very well known and established
onsite. Investigators also discovered that the valve
was capable of being locked closed as well as worryingly open, which could have led to
confusion, coupled with the operators not removing the air lines, could have been the
root cause. Regardless the procedure should never have
been allowed to happen without a blind flange, which would have been a form of double protection.
And this was reflected in OHSA’s investigation into the disaster, which found that phillips
pretrolium had a: Lack of process hazard analysis employing
Inadequate standard operating procedures. The legs came into question for not having
a fail-safe block valve and an Inadequate lockout/tagout procedure in the from of the
double locked but not double blocked procedure. Further more there was on site a Lack of combustible
gas detection and alarm system which didnt give workers warning of an impending incident.
Also it was found that the fire wasnt helped by the Presence of ignition sources and Inadequate
ventilation systems for nearby buildings. Philkips was fined 4 million dollars for the
infractions that led to the explosion as well as improve working prqactises across the company
and its sister enterprises. The ramifications from the event would spread
widley across the whole industry, helping improve safety, although things are never
as safe as they should be. This video is a Plainly Difficult production.
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