TRANSMISSION


gas move along these transmission pipelines at pressures from 200 psi to 1500 psi. As the gas is transported, the pressure drops in the lines due to resistance. Pipeline operators place compressor stations along the ROW to increase and replace the lost pressure.


Compressor Stations


Compressor stations are strategically placed along the transmission line as interim pumping stations that in- crease the pressure to maintain re- quired flow rates. These compressor stations are located at engineered dis- tances approximately 50–60 miles apart. This process is similar to relay pumping in the fire service.


Inside and outside these compres-


sor stations are valves that control the flow of gas. In transmission pipeline emergency, simply shutting off the flow of gas does not immediately cease the flow and stop the problem. It will take a long time, 2 to 3 hours or longer, for all the gas to leak from a pipe. Large gas valves should only be op- erated by utility personnel. The sudden change of pressure in the system could cause a disaster.


Storage


Throughout the natural gas system there are many types of storage facilities which vary widely in size and design based on the product stored and the location and need within the pipeline system. Storage helps to maximize the use of pipeline sys- tem capacity year-round and creates addi- tional flexibility in operation of the pipeline system in order to have large vol- umes of natural gas on hand available for delivery to customers in peak demand episodes.


Natural gas may be stored either under-


ground, like in salt caverns and other geologic formations, or in aboveground


Natural Gas


FIGURE 3.11 Natural gas is usually stored in large underground reservoirs.


41


STREET SMART TIP Any firefighter


knows that a large, long line with high pressure will carry a lot of water. It would take a while for several miles of 22” large diameter hose line to drain out. Imagine a 42” pipeline carrying product at 100 psi. How long will it take to stop leaking? Right ... A long time!


FIGURE 3.10 Transmission compressor station.


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