[Music] Clark: We started this day as a normal day,
of any the days that we do at work. At around 11:30, our lives changed forever. Narrator: June 9, 2009. The ConAgra Slim Jim Plant near Garner, North Carolina. A catastrophic explosion resulted from the
accumulation of dangerous levels of natural gas during indoor purging of new piping. Beamer: You think, come an emergency,
you're just going to jump on top of things and you're going to be just like the TV
and you know, Superman and save everybody. It's funny; it gets surreal.
And I couldn't even remember how to dial 911. Narrator: February 7, 2010. The Kleen Energy Power Plant under
construction in Middletown, Connecticut. A devastating explosion occurred when natural gas
was used to clean piping during a gas blow. Two deadly blasts ... [Sound of explosion] eight months and hundreds of miles apart. The cause of both accidents, common but dangerous
practices that release natural gas near work areas. Moure-Eraso: The Chemical Safety Board found that
the tragic accidents at ConAgra Foods and Kleen Energy were caused by planned and intentional natural gas releases. There are safe alternatives to the
hazardous practices that caused both accidents and we believe they should be used. [Music] Narrator: The accident at
ConAgra Foods Slim Jim production plant occurred during the installation and commissioning
of a new gas-fired industrial water heater, manufactured by Energy Systems Analysts or ESA. Several days prior to the accident, a new steel gas pipe
was connected to a natural gas supply pipe located on the roof of the plant. The newly installed gas pipe ran over 120 feet
along the roof and then down into a utility room, where the new water heater was located. The new gas piping was pressure-tested with air to
check for leaks, along with the existing supply pipe. No leaks were found. ConAgra employees then used natural gas to purge
or remove air from the supply pipe prior to use. Attaching a temporary hose to the supply pipe,
ConAgra workers vented the flammable gas directly outdoors. However, they did not purge the air from the
new steel pipe leading to the water heater. On the day of the accident, an ESA worker was
attempting to remove air from this new piping prior to lighting the heater. But ConAgra did not always
require piping to be purged outdoors. The gas supply valve on the roof was opened. Then the ESA worker opened a valve near the water heater, allowing gases to escape through an opening in the pipe. However, he was unable to light the heater and evidently concluded that this was
caused by air remaining in the pipe. So he continued venting the pipe intermittently
into the utility room, over two and one-half hours. But the air had left the pipe and
invisible natural gas began entering the room. No one used combustible gas detectors
to monitor the atmosphere. Instead, workers used an unreliable practice; they trusted their sense of smell to
warn them of the presence of natural gas. They were unaware that the gas had built
up to a dangerous level inside the building. Shortly before 11:30 a.m., the natural gas
found one of several potential ignition sources, perhaps an electrical device,
and ignited ... [Sound of explosion] causing a catastrophic explosion. The building construction included
prefabricated concrete roofing slabs known as "double Ts",
weighing about 12 tons each. Many of these double Ts came crashing down to the floor,
more than 20 feet below, injuring and trapping workers. [Sound of explosion] Narrator: More than half of the roof
either collapsed or was severely damaged. Four people were killed, including the ESA employee,
who died due to burn injuries over five months later. A total of 67 people were sent to the hospital,
including three for life-threatening burns. Among those killed was Deborah Pettaway's
33 year old son, Louis Watson, who worked with his mother at the plant. Ms. Pettaway, a longtime ConAgra employee, spoke directly to CSB Board members during a
public meeting held eight months after the accident. Pettaway: Louis was and he was my son.
And he was my only son. And now he's gone
and I can't hear or see him anymore. If somebody don't look into it now,
it's going to happen again. MacKenzie: During the ConAgra investigation, we
looked into the practice of purging natural gas indoors. And what we found was that this practice
resulted in a number of catastrophic incidents across the nation. These incidents resulted in severe injuries
and in some cases fatalities. And the Agency as a whole became very concerned
that the practice of purging natural gas indoors was a lot more commonplace than we initially thought. Narrator: Accidents caused by purging
include a May, 2008 explosion at a Hilton Hotel under construction
in San Diego, California, that injured 14 workers. New piping was purged indoors without
monitoring the atmosphere for flammable gases. MacKenzie: Natural gas often has
an odor added to it, mercaptan. And this odor is put there, so that people
can recognize when natural gas is present. However, people don't realize that
they can become desensitized to odor. Narrator: The CSB also noted
that new gas pipes and containers can remove the odorant from natural gas,
an effect known as "odor fade." MacKenzie: One of the lessons we've learned
from ConAgra and some of these similar incidents is that people cannot rely on their sense of smell
to know when a gas is present. Instead of using their sense of smell,
employees should be using combustible gas detectors to monitor the atmosphere
for dangerous levels of natural gas. Narrator: The CSB made urgent recommendations
to several code organizations, including the National Fire Protection Association or NFPA, to require purged gases to be
directly vented to safe locations outdoors, require the use combustible gas monitors during purging and warn workers against relying on
odor alone for detecting gas releases. In August 2010,
the NFPA agreed to an emergency code change. Moure-Eraso: I am pleased that the
National Fire Protection Association made our CSB recommendation a high priority and took immediate steps to
improve the National Fuel Gas code. Narrator: Just two days after the Board
issued its ConAgra urgent recommendations, another deadly explosion occurred as the result
of a planned, intentional natural gas release. In February 2010,
construction was almost finished on the new Kleen Energy natural gas-fueled
power plant in Middletown, Connecticut. New piping had been installed
from the natural gas supply line, to massive precisely constructed turbines
that generate electricity. Because debris such as rust or welding slag
can remain in the pipes after construction, pipes must be cleaned to ensure that the debris
does not damage the turbine blades. At Kleen Energy, this was
accomplished through a series of gas blows. Large volumes of high-pressure natural gas were forced through piping to
blow out debris directly into the atmosphere. On Sunday, February 7,
workers prepared for the natural gas blows and made efforts to control potential ignition sources
outside of the power generation building. But ignition sources are difficult to completely eliminate. In addition, metal debris expelled from piping can
strike other objects ... [Sound of metal on metal] causing sparks that can ignite the gas. More than 150 workers were at the plant that day,
including over 50 inside the power generation building. Only about 15 of the 50 were actually
involved in conducting the gas blows. Beginning at 7:30 a.m., gas and debris
were released from a number of open pipes just outside the power generation building. Fifteen gas blows took place that day,
over a four-hour period. Gas company records show that
some two million standard cubic feet of natural gas were released to the atmosphere that morning, enough to fuel a typical American home
every day for more than 25 years. Around 11:15 a.m., gas was blown through
an open pipe into a congested outdoor area, next to the power generation building. The natural gas accumulated to dangerous levels,
contacted an ignition source and exploded. [Sound of explosion] Narrator: Six people were killed and at least 50 were injured. Holmstrom: The CSB believes that the use of
flammable natural gas in gas blows is inherently unsafe and alternative methods should be used. Tillema: During our investigation of the incident, we
found that it was troublesome how common the practice was. Narrator: The CSB found that although blowing
out pipes with natural gas is seen as convenient, there are many readily available safer alternatives. Tillema: For example,
General Electric's a major turbine manufacturer, has been recommending since 1999
to their customers to do air blows. Narrator: Other alternatives
include blowing with nonflammable nitrogen or using a cleaning device called a pig, pushed by air. These methods avoid the danger of fire or explosion. The CSB found that despite the
existence of safer alternatives, blowing out pipes with flammable natural gas
is still the most popular method. Since 2001, this practice has led to at least
two other fires and explosions at gas power plants. Tillema: We learned that a lot of natural gas power plants
are being constructed in the next few years, so the potential for a repeat accident
like what happened at Kleen is very real. Narrator: The CSB noted that the
Occupational Safety and Health Administration has not issued a standard that
addresses the safe handling of natural gas. Following the tragedy at Kleen Energy, the CSB made 18 urgent safety recommendations
to regulators and other organizations. The CSB called on OSHA to develop a standard on
fuel gas safety to prohibit natural gas blows, ban purging flammable gases indoors and prohibit work activities where a
flammable atmosphere could develop. The CSB also recommended that the NFPA
and American Society of Mechanical Engineers change their codes to require the use of
inherently safer alternatives to natural gas blows. Finally, the Board urged major gas turbine manufacturers
to provide their customers with comprehensive technical guidance on safe
alternatives to natural gas blows. [Sound of explosion] Narrator: Unfortunately, serious accidents
involving intentional releases of fuel gases continue. In July, 2010, an explosion rocked the U.S. Steel plant
in Clairton, Pennsylvania, injuring 12 workers. Under an approved work plan, employees
opened a flange on a live coke oven gas pipe, releasing the flammable gas into a
congested work area, where it ignited and exploded. Holmstrom: The main lesson is the importance of using
safer alternative methods for conducting work activities, particularly flammable gas should not be released
in the vicinity of workers and sources of ignition. Narrator: In Connecticut, that lesson is being adopted. As recommended by the CSB,
the State's Governor issued an Executive Order, banning the use of natural gas blows
during power plant construction. Holmstrom: The action taken by the State of Connecticut
to ban gas blows to clean fuel gas piping is a model for the rest of the country,
in terms of protecting workers. [Sound of explosion] Moure-Eraso: The deadly accidents at Kleen Energy
and ConAgra Foods were entirely preventable. At the Chemical Safety Board, it is our hope
that the standards will be put in place to require safer practices,
which we believe will save lives. Narrator: For more information on the CSB's investigations
into the accidents at ConAgra Foods and Kleen Energy, please visit CSB.gov. [Music]
Oh captan mercaptan.
I work at a gold mine and stench gas (mercaptan) is our low tech fail safe alert. We will send out evacuation orders over comms but also release stench into the vent system. It's very effective but inderstanding of the article that like anything it cant be used too much.
National Geographic magazine published a scratch-n-sniff smell survey. Mercaptan was one of the samples.
All you have to do is look for the buzzards circling overhead... otherwise, just carrion. (my dad joke of the day)
https://www.popsci.com/gas-leaks-are-designed-to-attract-turkey-vultures/
I found a lot of new and interesting information in this video. For some reason I'm fascinated by industrial disasters.