GAS Compressor Stations and Emergency Shutdowns
Compressor stations play an important “push” role in moving natural
gas through a vast interstate pipeline network.
On its journey from production to end user, natural gas is compressed and
pushed along delivery systems by 700 to 1,600 pounds per square inch of pressure.
Over distance, friction and elevation differences
slow the natural gas and reduce the pressure. Strategically located compressor stations maintain
the pressure and velocity of the natural gas by giving it a much-needed “boost.”
Compressor stations are highly regulated facilities that must meet
rigorous safety standards established by the Federal Energy Regulatory Commission
and the U.S. Department of Transportation. In theory at least, compressor stations integrate
a variety of safety systems and practices designed to protect the public, its employees
and the operator’s property. In reality,
these pipeline properties are very filthy due to all the blowdown and gas
pipeline deposits that must be removed from inside the line using the pigging
methods. Fortunately for the operators,
very few people have done testing of the soil or water on their property, so
they have gotten away with many environmental violations over the years. The reason we know that these properties are
filthy dirty, is based on the Phase I and Phase II investigations we have done
during property transfers, i.e., when one operator sells to somebody else. We have found heavy pollution with petroleum
hydrocarbons, gases, metals and even PCBs since they were used extensively at
these gas compressor stations.
Every compressor station is equipped with a state-of-the-art emergency
shutdown system that automatically and safely halts operation when the slightest
irregularity is detected.
The emergency shutdown system stops the compressor units, then isolates
the compressor station piping and releases the natural gas from within the station
into the atmosphere in a safe and controlled manner. In other words, they contaminate the area with
millions of cubic feet of methane every time there is shutdown: millions of cubic feet. In addition, all emergency shutdown systems are
fully tested annually per Department of Transportation regulations.
An emergency shutdown is a very rare occurrence (do not hold
your breath on that, as they classify them most of the time as standard maintenance
and that way they avoid reporting these occurrences to the regulators), but one
for which they are well-prepared. In the
event of a shutdown, local public safety and/or emergency management officials are
immediately notified and thoroughly briefed so they may respond to questions and
concerns as needed.
Frequently Asked Questions
The following questions and answers are designed to help our compressor
station neighbors understand exactly what happens during an emergency shutdown:
Q: What causes an emergency shutdown?
A: Natural gas and flame sensors, located inside the compressor
building, constantly monitor the station. If a problem is detected, the emergency system
will activate automatically in order to protect the community, station personnel
and facility.
Q: Is this all done by computer?
A: Yes, but there are also manual shutdown buttons strategically
placed throughout the facility which can be activated by station operators. Every
one of our compressor stations is operated and maintained by highly skilled, experienced
personnel trained to safely maintain the station and its pipelines.
Q: What will I hear when an emergency shutdown occurs?
A: You will hear a very loud noise often compared to the sound of
a jet engine or a freight train. The sound
will last anywhere from one to four minutes. This sound is the result of the release
of pressure from the compressor station piping.
So, cover your ears because we will be blowing and hissing for all this
time in the middle of the night and disrupt your sleep – all in the name of
selling gas to you.
Q: What will I see when an emergency shutdown occurs?
A: You likely will see a large vapor cloud discharging into the
air. During an emergency shutdown, natural gas is released from a compressor station
very quickly in order to clear the natural gas and reduce potential danger. It appears
to form a cloud because compressed natural gas is under extreme pressure and the
velocity of the natural gas, upon its release, makes it colder than the atmosphere.
Q: Is it dangerous?
A: The natural gas released during an emergency shutdown is not
dangerous, unless of course catches fire and explodes, as it has happened in
the past and could also happen in the future. While release amounts vary from station to station,
they fall within strict guidelines mandated by federal regulations, although we
do not really report the correct amounts to the feds. Let them sleep in the desks and only act when
there is a disaster. The natural gas release
is necessary to reduce potential risk to the facility, employees and the surrounding
community.
Q: What is in the vapor cloud that is released?
A: Natural gas is a mixture of hydrocarbons, primarily methane
(95% or so). Because methane is lighter than
air, it rises and dissipates safely as it is absorbed into the atmosphere,
unless of course catches fire and explodes.
Q: What will I smell?
A: Natural gas is odorless and colorless. However, in some pipelines, an odorant called methyl
mercaptan (like the one that killed 4 poor DuPont workers in Texas last week) is
injected into the natural gas for safety reasons. Mercaptan creates a recognizable odor, often compared
to rotten eggs, which helps consumers identify or detect a leak. It is not harmful at small doses and will dissipate.
In some cases, the smell of mercaptan may
linger if minute traces of the odorant separate from natural gas that has risen
and been absorbed into the atmosphere.
Q: Do the same things happen during a routine maintenance shutdown?
A: No. Our system or a portion of it is occasionally shut down,
purged and tested to ensure it is operating safely and efficiently. Those shutdowns
and start-ups cause little or no disruption and are rarely noticed by our neighbors,
unless are valves and equipment are defective.
Then you will hear about it.
