Emergency Response Planning Guidelines (ERPG)

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No matter how well designed and operated a facility may bethere are times when an emergency occurs and animmediate response is required. This page discusses thetopics of emergency management and response. Furtherinformation is available Chapter 11 of Process Risk andReliability Management.

Emergency response falls under the broader rubric of Abnormal SituationManagement (ASM), in which a variable moves from the safe range, through thearea of trouble-shooting and on to a true emergency as illustrated in Figure 1.

Figure 1Operating Limits

Once a process variable moves outside its normal operating range it enters theregion of “trouble” (245-275 in the upper range in Figure 1). When a facility is in itsnormal operating range the system is controlled by its instrumentation; the operatorusually does not have a lot to do except keep an eye on things. It is when thingsstart to go awry , i.e., when the system runs into trouble that the skills of the

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experienced operators and maintenance technicians are called upon. As the systemmoves out of the trouble range (275 in the example) the system becomes increasingunsafe until eventually an emergency is declared (310 in the upper range of theexample; there is no lower emergency limit in this case).

Levels of Emergency

An emergency response can be divided into three phases.

The system is at or near the emergency limits, but the operators andsupervisors believe that they are able to return the plant to normal conditionsusing normal operating procedures and techniques. It is critical that theyunderstand the exact nature of the problem if they are to be successful in this.Many accidents would have been less severe had the operators not tried to“fight” the situation, but simply shut down the facility in an orderly manner.(On the other hand, a full facility shutdown is not always the best response toan incipient emergency because doing so increases the number of actions thatthe operator has to perform, and can stress many equipment items. Theadvantage of keeping the unit running is that the operators can concentrate oncorrecting the emergency situation. They do not have to simultaneously copewith bringing down all the other equipment in a safe manner. Moreover, theavoidance of a full shutdown means that the unit can be brought back on linerelatively quickly with minimal production loss).

1.

The second phase of an emergency occurs when the safety instrumentedsystem and other high reliability, automated devices (including relief valves)take over. At this point in time the role of the operator is simply to secure theunit as it shuts down.

2.

In the third phase of an emergency, the situation is out of control. There maybe a large fire or chemical release to contend with. The full emergencyresponse system is needed to minimize injuries, environmental damage andloss of equipment.

3.

Figure 2 provides more detail to do with the third phase. It shows the ways in whichemergencies can be initiated, along with the appropriate levels of response.

Figure 2Levels of Emergency


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At the top of Figure 2 are the possible causes of an emergency: either an internalevent such as the failure of a pump seal leading to a major fire, or an external eventsuch as a lightning strike or an explosion at an adjacent facility. These initiatingevents can be identified, listed and analyzed when conducting hazards analyses andpreparing a risk management plan. Factors to be considered when identifyingpotential accident scenarios include the location of a release, its magnitude, winddirection and the number of people who may be in the area at the time of therelease.

It can be useful to model some of the scenarios, particularly the release of hazardouschemicals so that, if the accident actually does occur, the emergency responders willhave some idea as to the size of the incident with which they may be expected tocope. Some companies even have on-line models that are available in real time.Then, if there is a release of that chemical, the response team can provide themodelers with current information so that a real-time prediction as to the magnitudeof the incident can be developed.

It is important to identify any chemicals that require special treatment during thecourse of an emergency. For example, the use of water on some chemicals maycause them to ignite. In these cases, they must be controlled with other chemicalagents.

A complicating factor is that most emergencies do not occur in isolation. Usually,there is a whole host of events going on at once. For example the immediateemergency may be hydrocarbon overflowing from a tank. However the cause of theoverflow may have been the loss of electrical power to the site. That loss of powermay also have compromised the fire-fighting capability of the emergency responseteam, or it may have led to a degradation of the internal communications channels.Moreover, if the spilled liquid were to ignite the subsequent fire could burn through acritical utility header. Environmental events, such as earthquakes, are particularlyprone to creating multiple, simultaneous emergency situations. For example, theearthquake that causes lines and vessels to rupture may also break the fire waterheader, thus placing the emergency response team in a less than enviable position.


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Emergency Operations

The first level of response can be termed “emergency operations”. A line operator ormaintenance technician notices that an emergency situation is developing andquickly responds to bring the system to a safe condition. For example, if a pump sealfails and flammable hydrocarbon liquids are being sprayed into the air, the operatorwill usually shut down and block in the pump, hose down the area, get the sparepump started and call in maintenance to repair the failed seal. The emergencycondition has been identified and corrected within just a few minutes.

If immediate operating response is not sufficient, the operator can shut downsections of the unit so that the affected equipment can be repaired. Procedures to dowith emergency operations and shutdown tell the operator how to do this withoutcausing any further damage and without jeopardizing other units. Once more, thefacility remains in operation.

As a general rule, sources of heat such as fired heaters and steam reboilers shouldbe shut down as an emergency develops. Cooling systems should continue to operatebecause they remove heat from the system. Utilities, such as the steam and airsupplies, should remain in operation in order to retain control of the equipment thatis still in operation.

If there is a major accident, an accurate head count will determine if anyone needsrescuing. Therefore, the facility managers must always know how many people areon the site at any one time. For larger facilities, they should also know roughly wherethose people are within the facility. If key-swipe cards are used, barriers can beplaced between major operating sections so that a person’s location is alwaysroughly known. The persons responsible for running the unit should always knowhow many people are on the site at any one time. For larger facilities, they shouldalso know roughly where those people are within the facility.

Local Emergency Response

If an operator or maintenance technician recognizes that the situation is out ofcontrol and cannot be addressed through emergency operations, he or she candeclare an emergency. With regard to the leaking pump seal the operator may not beable to get near the pump due to fumes in the area or because he feels that doing sowould put him in danger. Therefore he calls in the facility’s own emergency responseteam. The personnel on this team will be trained in the handling of emergencies, andthey will be issued with the appropriate equipment and protective clothing.

General Emergency Response

If the situation becomes too large for the emergency response team to handle thenthey can call for help from outside organizations, including the local fire department,ambulance services and other facilities in the area. The emergency plan must takeinto account the fact that these people are not familiar with the particular processwhere the emergency has occurred. Where possible, these outside agencies shouldhave the opportunity of training with the plant emergency response team.

In large industrial centers, such as the Texas Gulf Coast, the various plantscoordinate their emergency response efforts in a mutual support system. So, if afacility has a fire and needs additional fire-fighting trucks, they will be supplied byneighboring units. If the incident is bad enough, there will be a ripple effect ofemergency equipment moving toward the affected site for dozens of miles.

It is important that the press and the public be informed of what is going on at thesite, particularly if anyone is in any danger. Facility management should take theinitiative when communicating with the public, and they should be open and asforthright as possible (given that there will a good deal of uncertainty in the earlystages of the response to an emergency). Telephone lines and other links for publiccommunication must be available, and they must have sufficient capacity that theydo not become jammed with unnecessary calls.


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Recovery Operations

As soon as the site is secure, and there is no danger to anyone, recovery ofequipment and chemicals can start. At this time, the plant may contain manyunexpected hazards, such as the danger of being struck by falling equipment thathas had its foundations weakened by fire. Or there may be pockets of spilledchemicals in unexpected places. Some equipment may be contaminated withhazardous chemicals, and may need to be specially treated before it can be returnedto service, or before the operators or maintenance personnel can use it.

Investigation and Follow Up

If the incident is serious, an investigation as to its cause will start as soon aseveryone is out of danger. It is particularly important to find out what happened ifthere are reasons to believe that it could happen again, maybe at another site.

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Emergency Response Planning Guidelines (ERPG)