CHAPTER 4 RESPONDING TO GAS EMERGENCIES


STREET SMART TIP


Responders wouldn’t handle a 350 kV electri- cal transmission line; neither should they try to handle a 500 psi gas transmission emergency.


FIGURE 4.16 The majority of gas pipeline damage is caused by digging into the pipeline by contractors, excavators or homeowners.


incidents the responders will adopt a defensive or nonintervention mode because they often lack the resources and/or capabilities to take action.


On occasion a pressure relief STREET SMART TIP


“big Gas—big prob- lems.” Transmission lines and large distribu- tion lines need experts. never close any trans- mission or distribution valves without utility expertise and guidance. Responders are not equipped at this level to be offensive. unless you are sure it is a customer service valve respon- ders should be at least in a defensive mode, and (even better) in a nonintervention mode.


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valve may operate normally but be perceived as an emer- gency due to the presence of odorized gas in the area. Pres- sure Relief Valves (PRV) pro- tect gas lines from excess pressure. If the pressure down- stream is dangerously high, the relief valve will operate. This valve operation could be ex- tremely loud and very discon- certing to the public or untrained responder. One pos- itive aspect in these events is that natural gas rises and the re- lease will dissipate quickly in an open area. Responders should never try to restrict or shut a relief valve by operating its valve. It is better to contact the utility company and allow the experts to take over.


FIGURE 4.17 Pressure relief valve at a gate station/ city gate.

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