# petroleum refining- what are those stacks with the flames at the top **URL:** \ **Category:** Factual Questions\ **Created:** [March 3, 2012, 3:25pm UTC](https://boards.straightdope.com/t/petroleum-refining-what-are-those-stacks-with-the-flames-at-the-top/614643 "2012-03-03T15:25:21Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [March 3, 2012, 3:25pm UTC](https://boards.straightdope.com/t/petroleum-refining-what-are-those-stacks-with-the-flames-at-the-top/614643/1 "2012-03-03T15:25:21Z")
In the downriver Detroit metro area, there are several oil refineries which I drive past fairly regularly. There’s always at least several fairly tall and skinny chimneys/stacks which have flames burning at the top. What are they burning off? If it’s a combustible/flammable gas, wouldn’t it be something better captured and used rather than just making a giant metal candle? ---
**Author:** ![coremelt](https://avatars.discourse-cdn.com/v4/letter/c/4491bb/32.png) [@coremelt](https://boards.straightdope.com/u/coremelt)\ **Post date:** [March 3, 2012, 3:29pm UTC](https://boards.straightdope.com/t/petroleum-refining-what-are-those-stacks-with-the-flames-at-the-top/614643/2 "2012-03-03T15:29:29Z")
> **[Gas flare](https://en.wikipedia.org/wiki/Gas_flare)** > > A gas flare, alternatively known as a flare stack, flare boom, ground flare, or flare pit is a gas combustion device used in places such as petroleum refineries, chemical plants and natural gas processing plants, oil or gas extraction sites having oil wells, gas wells, offshore oil and gas rigs and landfills. > In industrial plants, flare stacks are primarily used for burning off flammable gas released by safety valves during unplanned over-pressuring of plant equipment. During plant or partial pl... On oil production rigs, in refineries and chemical plants, its primary purpose is to act as a safety device to protect vessels or pipes from over-pressuring due to unplanned upsets. Flare gas recovery systems are occasionally used to collect low flows of waste gas and return it to the Process Plant as opposed to burning the gas ---
**Author:** ![dzero](https://avatars.discourse-cdn.com/v4/letter/d/5f9b8f/32.png) [@dzero](https://boards.straightdope.com/u/dzero)\ **Post date:** [March 4, 2012, 3:24am UTC](https://boards.straightdope.com/t/petroleum-refining-what-are-those-stacks-with-the-flames-at-the-top/614643/3 "2012-03-04T03:24:26Z")
Thanks. Bonus: I love learning new technical jargon. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [March 5, 2012, 8:04pm UTC](https://boards.straightdope.com/t/petroleum-refining-what-are-those-stacks-with-the-flames-at-the-top/614643/4 "2012-03-05T20:04:48Z")
Here’s the sort of thing that safety device is intended to prevent: [Texas City Refinery Explosion](http://en.wikipedia.org/wiki/Texas_City_Refinery_explosion) Specifically: [QUOTE=Wikipedia] The particular type of disposal system serving the raffinate tower was a blowdown drum with an atmospheric vent stack, rather than an inherently safer and more environmentally sound knock-out tank and flare system. [/QUOTE] Note that BP itself was aware of the need to install a flare system: > [@](#): > > During 2002 [the explosion occurred in 2005], BP’s Clean Streams project proposed converting the blowdown drum to a flare knock-out tank, and routing discharges to a flare. When it was found that a needed relief study of the ISOM system had not been completed due to budget constraints, the Clean Streams project proposed adding a wet/dry system to the ISOM instead. 15 people were killed and 170 injured in the explosion and subsequent fire.