User:Milton Beychok/Sandbox: Difference between revisions

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Large LNG storage tanks are cylindrical  and have a low aspect ratio (i.e.,height to width ratio). They are typically constructed with a [[post-tensioned concrete]] outer wall and a high-nickel steel inner wall, with insulation between the inner and outer walls.<ref>[http://www.emacogroup.eu/tank%20ref.pdf Emaco Group: Case Studies]</ref> The tanks have domed roofs made of steel or concrete. The storage pressure in such tanks is quite low, less than 10 k[[Pascal (unit)|Pa]] (0.10 [[atmosphere (unit)|atm]]). Sometimes underground or partially underground tanks are used for storage.
In its liquid state, LNG is neither flammable or explosive. For LNG to burn, it must first vaporize, then mix with air in the proper proportions (the [[Flammability limit|flammable range]] is 5% to 15%), and then be ignited. In the case of a leak, LNG vaporizes rapidly, turning into almost pure gaseous), and mixes with air.  If the mixture is within the flammable range, there is a risk of ignition which would create [[fire]] and [[thermal radiation]] hazards.


Smaller cylindrical LNG storage tanks, about 1,000 m<sup>3</sup> (264,000 [[gallon]]s) or less, are usually [[vacuum|vacuum-jacketed]], pressure vessels. The storage pressure in such tanks may range from less than 50 kPa (0.50 atm)  to over 1,000 kPa (10 atm) and they may be either horizontal or vertical.
LNG tankers have sailed over 100 million miles without a shipboard death or even a major accident.<ref>[http://www.msnbc.msn.com/id/18556688/page/2/ MSN.com], MSNBC U.S. Thirst for Natural Gas Grows, AP</ref>
 
Some on-site accidents involving or related to LNG are listed below:
* October 1944: The East Ohio Natural Gas Company experienced a failure of an LNG tank in [[Cleveland|Cleveland, Ohio]].<ref name="CHIV">{{cite paper|title=Safe History of International LNG Operations|url=http://www.ch-iv.com|author=CH-IV|date=December 2006}}</ref> 128 people perished in the [[Cleveland East Ohio Gas explosion|explosion and fire]]. The tank did not have a dike retaining wall, and it was made during World War II, when metal rationing was very strict. The steel of the tank was made with an extremely low amount of [[nickel]], which meant the tank was brittle when exposed to the extreme cold of LNG. The tank ruptured, spilling LNG into the city sewer system. The LNG vaporized and turned into gas, which exploded and burned.
* Ocyober 1979: [[Lusby, Maryland]], at the Cove Point LNG facility a pump seal failed, releasing gas vapors (not LNG), which entered and settled in an electrical conduit.<ref name="CHIV" /> A worker switched off a circuit breaker, igniting the gas vapors, killing a worker, severely injuring another and causing heavy damage to the building. National fire codes were changed as a result of the accident.
* January 2004: [[Skikda]], [[Algeria]]. Explosion at Sonatrach LNG liquefaction facility.<ref name="CHIV" /> 27 killed, 56 injured, three LNG trains destroyed, 2004 production was down 76% for the year. A steam boiler that was part of a liquefaction train exploded triggering a massive hydrocarbon gas explosion. The explosion occurred where propane and ethane refrigeration storage were located.

Revision as of 18:32, 25 February 2011

In its liquid state, LNG is neither flammable or explosive. For LNG to burn, it must first vaporize, then mix with air in the proper proportions (the flammable range is 5% to 15%), and then be ignited. In the case of a leak, LNG vaporizes rapidly, turning into almost pure gaseous), and mixes with air. If the mixture is within the flammable range, there is a risk of ignition which would create fire and thermal radiation hazards.

LNG tankers have sailed over 100 million miles without a shipboard death or even a major accident.[1]

Some on-site accidents involving or related to LNG are listed below:

  • October 1944: The East Ohio Natural Gas Company experienced a failure of an LNG tank in Cleveland, Ohio.[2] 128 people perished in the explosion and fire. The tank did not have a dike retaining wall, and it was made during World War II, when metal rationing was very strict. The steel of the tank was made with an extremely low amount of nickel, which meant the tank was brittle when exposed to the extreme cold of LNG. The tank ruptured, spilling LNG into the city sewer system. The LNG vaporized and turned into gas, which exploded and burned.
  • Ocyober 1979: Lusby, Maryland, at the Cove Point LNG facility a pump seal failed, releasing gas vapors (not LNG), which entered and settled in an electrical conduit.[2] A worker switched off a circuit breaker, igniting the gas vapors, killing a worker, severely injuring another and causing heavy damage to the building. National fire codes were changed as a result of the accident.
  • January 2004: Skikda, Algeria. Explosion at Sonatrach LNG liquefaction facility.[2] 27 killed, 56 injured, three LNG trains destroyed, 2004 production was down 76% for the year. A steam boiler that was part of a liquefaction train exploded triggering a massive hydrocarbon gas explosion. The explosion occurred where propane and ethane refrigeration storage were located.
  1. MSN.com, MSNBC U.S. Thirst for Natural Gas Grows, AP
  2. 2.0 2.1 2.2 CH-IV (December 2006). Safe History of International LNG Operations.