BY FRANK MONTAGNA
Even if your utility doesn’t pipe high-pressure (HP) steam underground to buildings for heating, you should consider response to HP steam emergencies. About 90 percent of all electrical generation in the United States uses HP steam to spin the turbines that generate the electricity. Do you have a large apartment, industrial, or hospital complex in your response area? Often, housing projects, industrial building complexes, hospitals, and some commercial occupancies have their own electrical generating plants and provide steam for heat or for industrial purposes. If you have any of these buildings in your area, they may use HP steam, and you need to know the dangers of responding to incidents involving HP steam.
The various HP steam incidents that you might be called to respond to include an HP steam leak in an electric generating plant, a cataclysmic underground failure of an HP steam distribution system, or a ruptured HP steam pipe inside of a building. In any case, you need to know the hazards and how you can mitigate them. Like so many other utility emergencies, usually the fire service cannot fix the problem. Although we are nonetheless responsible for life safety at these incidents, we must wait for the appropriate utility personnel to resolve the problem. Hopefully, while waiting, we can rescue those in danger and prevent anyone else (including ourselves) from becoming endangered.
Luckily, serious steam incidents are rare; because of this, few of us have response experience. What are the hazards? What precautions must we take? How can we mitigate the dangers? Who do we call for help?
High pressure has been defined as steam at a pressure above 250 pounds per square inch gauge (psig), but you can encounter much greater steam pressures at electrical generating plants. The pressures there can reach 2,500 psig, and the temperatures can be as high as 900°F. The exact temperatures and pressures that you may find in your response area will vary, but they all can cause devastating injuries and death.
Steam is water that has been converted into a gas by heat. At sea level, 212°F will convert water into steam. You might think that steam is the whitish cloud streaming from a boiling tea kettle, but it is not. What you see is a mist of water that forms as the hot steam cools and starts to condense back into a water mist. It is no longer steam. If you look carefully at the tea kettle’s spout, you might see a clear area between the spout and the white cloud of condensed steam. That is steam, and it is invisible.
Electrical Plant Pipe Rupture
In most electrical generating plants, superheated steam turns the turbines that produce electricity. The steam exiting the turbines is condensed back into water and then reheated and turned to steam again and routed to the turbines. Some of the steam exiting the turbines can be routed through underground pipes to surrounding buildings to provide heat for buildings and for industrial purposes. A major steam pipe rupture at generating pressure and temperature would likely be fatal to anyone in the vicinity of the break. A pinhole leak in an HP pipe at 900 psig can cut through a thick steel bolt like a hot knife through butter.
|(1) Park upwind, out of the steam plume, at least one block away, and out of the potential asbestos hazard released by the damaged steam main. (Photos by Anthony Natale, courtesy of the Emergency Response Team, Consolidated Edison of New York.)|
Besides the dangers of steam at a high temperature and a high pressure leaking into a generating plant, a response to a burst steam pipe there poses other dangers. A typical generating plant is an open space with multiple levels created by metal catwalks. The condensing steam will drastically reduce visibility in the plant, resulting in disorientation and obscuring hazards such as pits of near-boiling water, caustic chemicals, and various moving equipment. The sound of such an HP steam leak can be like that of a jet engine, making voice communication difficult. Other potential hazards are hydrogen gas, which is used to cool the turbines, and natural gas, which is frequently used to power the turbines. If a steam pipe rupture damages the gas piping, both gases will pose a fire and explosion hazard. Another hazard is the asbestos insulation often found on the steam piping.
Given the level of hazard encountered in an electrical generating plant, automatic entry by the responding firefighters is not a safe tactic. On arrival, establish communications with a responsible person at the plant, determine the problem, and find out if anyone inside is in danger. The only reason we should enter the plant is to save life, and then only after consulting with responsible utility personnel; enter with a minimum of personnel, with maximum supervision, and with a utility worker who knows the plant and its hazards who will act as guide. Fire personnel should wear full personal protective equipment (PPE) including self-contained breathing apparatus (SCBA). At an HP steam leak incident in a generating plant, a Fire Department of New York (FDNY) captain and his firefighters were searching for an unaccounted-for employee. Condensed steam was present, but it was not dangerously hot at first. It suddenly became untenably hot, causing serious burns to the captain and to his crew as they rescued him.
- Establish contact with plant personnel.
- Determine the existing problem.
- Find out if all employees are accounted for and if anyone inside needs to be rescued.
- Obtain a knowledgeable guide if you plan on entry.
- Wear full PPE including SCBA when making entry.
- Maintain close supervision of the entry team.
- Be prepared for verbal communication difficulties if you are planning to enter.
- Be aware that interior conditions can worsen rapidly.
- Consider this a hazmat incident because asbestos may be present.
Underground Pipe Rupture
A pipe rupture under the street or sidewalk is another type of incident you may encounter. The steam’s pressure and temperature are less than those found in the plant. In New York City, steam escaping from an underground pipe can be as hot as 350°F and pressurized to 170 psig. Although it is no longer officially HP steam, it is high enough to present a danger, and it will still sound like a jet engine.
A tow truck driver in New York City was scalded to death while stopped at a street light when a steam pipe beneath him ruptured, releasing scalding steam. As mentioned, the temperatures and pressures can vary in different locales.
At another incident, a disabled woman was scalded to death in her bed when a pipe in the street ruptured, sending rocks and debris into the air. Her window was broken, allowing the hot steam condensate to enter her room.
An underground steam pipe rupture will blow up and out of the ground, spewing pavement, dirt, rocks, and often asbestos out of the hole at a velocity of as much as 200 miles per hour. It will also eject slugs of very hot water, and the condensing steam will obscure the ruptured pavement and its surrounding area.
A rupture can damage underground gas and electric utilities, creating a gas leak, while damaged electric utilities could provide the ignition source for a gas-fueled fire. Also, gas may migrate underground into surrounding buildings. Anyone unfortunate enough to be near the rupture when it occurs may be instantly killed or severely injured and unable to escape the scalding steam. Projectiles ejected by the rupture can injure and kill pedestrians and firefighters.
When responding to these incidents, be aware that it is likely that the underground piping is wrapped in asbestos and that asbestos will be entrained in the material spewed from an underground rupture. Request the response of the utility or other entity responsible for maintaining the pipeline. These personnel will be able to stop the flow of steam and repair the pipes. Stage upwind from the incident, and test for asbestos as soon as it is practical. You should assume that asbestos is present and that any personnel, equipment, and civilians exposed are contaminated and need decontamination. Water lines may be damaged, which could complicate any firefighting operations in the area.
Set up the command post (CP) out of the potential asbestos contamination area and remote enough so that the sound of the escaping steam does not interfere with communications. Consider setting up incident command inside of a convenient building. Immediately rescue incapacitated victims when possible, remove and exclude civilians from the affected area, and implement mass decontamination procedures.
Because of the potential damage to underground utilities, check surrounding buildings for the presence of natural gas and electrical problems and any victims who may have been trapped or injured. Rocks, dirt, and debris can break windows in nearby buildings, exposing occupants to scalding steam and putting them at risk of injury or death.
- Notify the steam utility to respond as well as the gas and electric utilities as a precaution.
- Set up the CP where voice communications will be possible. Consider using a nearby building.
- Wear full PPE if entering the steam cloud.
- This is likely an asbestos incident, so plan for decontamination of firefighters, civilians, tools, apparatus, and equipment.
- Rescue and remove those in danger. This may include pedestrians as well as those trapped in their vehicles by the steam.
- Check buildings for steam infiltration. Close windows, and shut down the heating, ventilation, and air-conditioning system.
- Consider evacuating buildings using exits other than the front entrance to avoid steam entry. Also consider protecting occupants in place.
- Check buildings for anyone who is unable to evacuate.
- Monitor the area and buildings for leaking gas.
- Check the subway and underground railways and roadways for damage and steam infiltration.
Pipe Rupture in a Building
An HP steam pipe rupture in a building can release scalding steam at high pressures, quickly causing death and injury to nearby occupants. In an incident in a New York City high-rise building, seven people were scalded to death at their desks when an HP steam pipe in the wall ruptured. In another, firefighters responding to an incident at a New York City hospital were unable to enter a room to vent it because of the extreme heat caused by a burst HP steam pipe.
A utility may not supply the steam to the building; many buildings use private steam-generating plants. Even when the utility supplies the steam, once the steam enters the building, building personnel are typically responsible for the maintenance and control of the system. In such instances, consider calling the steam utility for advice on how to handle the situation.
When responding to end-user emergencies in structures, you must again consider asbestos, as it was once commonly used to insulate pipes. Consider decontamination of exposed firefighters, gear, tools, and civilians.
A building supplied with HP steam will have a valve room that contains the controls for the structure’s supply. It is not usually a safe practice for firefighters to shut an HP steam valve, and it is never safe for them to open one. Shutting the wrong valve or opening any valve can have dangerous results.
|(2) Steam vapor coming up from the ground or from a manhole comes from a leaking piece of equipment or storm water runoff that has overwhelmed the drain and come in contact with the hot steam pipes. In a water or sewer main break, a large volume of water escaping underground can cause a steam main to fail, creating a very hazardous condition.|
In New York City, steam valve rooms have one valve labeled “Inside Service Valve,” which will shut down the steam to the building. FDNY firefighters are permitted, if necessary, to close the Inside Service Valve, but it is usually safer to leave the closing of the system valves to the utility or responsible building personnel. An important consideration: After a steam valve is closed, you must follow a specific procedure before reopening it; failure to do so can result in a burst pipe and injury or death to whoever is in the vicinity. Any time a firefighter shuts a valve, you must notify the utility or the responsible building personnel.
The escaping steam from a ruptured HP steam pipe will severely burn and even kill people nearby; and firefighters may not be able to enter the area, even in full PPE, until the area has cooled. Any venting may have to be done from the exterior when possible.
As in the case of a generating station, conditions can change rapidly, so firefighters should wear full PPE when operating in the affected area. Even with full gear, if the operation is prolonged, firefighters will have to be rotated frequently, since the elevated temperatures can rapidly debilitate them.
A ruptured HP steam pipe in a building will present a communication problem but not as severe as the larger and higher-pressure pipes in the generating station and in the street. There will also be a visibility problem in the area of the leak.
Just because a building is supplied with HP steam, it does not mean that what is leaking is at high pressure. It could just be a leaky radiator and not nearly as hazardous as a ruptured HP pipe.
- Contact the entity responsible for control and repair of the system.
- Consider requesting the steam utility to respond as an advisor even if it is a private system.
- Locate the origin of the leak, determine the hazard presented, and consult with building personnel to determine what action you can take to resolve the problem. Is there a valve that you are permitted to shut? If it is utility-supplied steam, utility personnel may be able to shut off the steam in the street.
- Determine who in the building is in danger.
- Evacuate occupants from the danger area.
- Ventilate the affected area.
- Consider that asbestos may be involved and that it is a hazmat incident.
- Wear full PPE when entering the affected area.
- Consider the need to decontaminate.
- Consult with responsible utility/building personnel before closing any valves, and do not open any valves.
- Be aware that when outdoors, steam will cool relatively quickly, so the temperature will drop as you distance yourself from the leak. Indoors, however, temperatures will become dangerously elevated quickly.
Because all HP steam emergencies mentioned in this article are high-hazard/low-frequency incidents, take the following precautions:
- Find out if you have HP steam in your response area.
- Preplan your response as follows:
- Visit the sites for familiarization.
- Learn the potential hazards at each location.
- Determine in advance the responsible party to contact at such emergencies and the help he can offer you.
- Decide what actions you can take at these incidents and what you should not attempt.
- High-hazard/low-frequency incidents require repeat training.
- Have a decontamination plan, and train on it.
You may not have any HP steam in your response area, but what about the areas to which you respond on mutual aid? Are there any new building complexes being erected in your response area? If so, will they be generating their own electricity, and will they use HP steam? A response to an HP steam incident is not one that you want to attempt without prior planning, so make the effort to find out if such a response might be in your future.
FRANK MONTAGNA retired from the Fire Department of New York after 43 years; he was a battalion chief for his last 26 years. He taught courses at John Jay College based on his book Responding to Routine Emergencies (Fire Engineering Books) and has published more than 40 articles on various aspects of firefighting. He lectures on utility emergencies and fires and other fire-related topics.
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