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News San Bruno, California explodes

  1. Sep 9, 2010 #1
    It looks like a gas line explosion.

    http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2010/09/09/BADP1FBJRS.DTL&tsp=1 [Broken]

    I don't know how long this link will work for this thread's purposes, but here's a link to a live news report with live video:

    http://abclocal.go.com/kgo/livenow?id=7659504

    Will this be a nationwide media event, or will this go mostly unnoticed?
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 10, 2010 #2
    My response can be summed in two words: HOLY ****!

    It's all over CNN, both web and tv, so I'd say it's nationwide. 170 homes burned, 4 dead and over 28 injured, and burns being what they are more will die from infection over the next weeks->months. Finger pointing which has already begun aside, apparently at least one resident claims to have been smelling the additive in NG for weeks... was this reported? This is pretty horrific, but it's going to be a while before cause is determined I think.
     
    Last edited by a moderator: May 4, 2017
  4. Sep 10, 2010 #3
    It wasn't all over CNN when it happened. I found out about it 3 hours after the fire started. I went to my television, checked out CNN, Fox, MSNBC, and CNN's "Headline News" channel. None of them had any coverage.
     
  5. Sep 10, 2010 #4

    lisab

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    I first saw it online, on MSNBC. It was about an hour after it started, I think. Then I looked for it on the tube, and the first I saw it was on CNN's Headline News channel, and I only looked there because I was looking for it. Wow, some of those pix are just crazy - looks like Dante's hell!
     
  6. Sep 10, 2010 #5
    It must have been uniquely terrifying to be in such a massive inferno. One fellow said he heard his siding pop off, and of courser the heat was pervasive! Poor bastards.
     
  7. Sep 11, 2010 #6
    No scandal or politics and the news is soon forgotten.

    http://www.euronews.net/2010/09/10/gas-explosion-sparks-massive-fire-in-san-francisco/

    This is a good example of our crumbling infrastructure. My morning paper says the gas lines were installed in the 50's and 60's. Newer pipe is corrosion resistant.

    I have read three different versions of the size of the pipe that ruptured. First it was 22 inches, then 24, and the morning paper says 30.

    That is one heck of a big high pressure line to be running through a housing development.

    Edit: Here is a google map of the fire area. It seems odd to be able to zoom in on houses that are no longer there.

    http://maps.google.com/maps/ms?msa=0&msid=115203651140089107127.00048fdfe759741e3afd2
     
    Last edited: Sep 11, 2010
  8. Sep 11, 2010 #7
    based on the adjacent parks, i'd guess the houses weren't there when the line was installed.
     
  9. Sep 11, 2010 #8

    Ygggdrasil

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    Pacific Gas and Electric, the company that owns the gas line in San Bruno that exploded, has previously been cited for slow responses to gas leaks leading to fatal explosions:

    http://blogs.sfweekly.com/thesnitch/2010/09/pge_explosion_fire.php

    Of course, the causes of this explosion still need to be investigated.
     
  10. Sep 11, 2010 #9
    They haven't made any move to dodge responsibility (not that they could), of course... this will not bring back lives.
     
  11. Sep 11, 2010 #10

    mheslep

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  12. Sep 11, 2010 #11
    I find it hard to believe that a 30" pipe under that kind of pressure would be accessible to digging by anything a homeowner had access to. Given the age of the pipe, couldn't low-level seismic activity and subsequent shifts and shear have done the damage along with corrosion? It seems imprudent to allow a housing development to be built above such structure in a notoriously seismically active region.

    That said, the company, PG&E has said flat out that they're taking (not blame yet) responsibility for this, and the aftermath. Such a rapid response would seem to indicate that maybe this is a local or company-specific issue, and not a generalized infrastructure issue, thus supporting your position.
     
  13. Sep 12, 2010 #12

    mheslep

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    Need not have been a homeowner w/ a shovel. Could have been heavy equipment months ago that weakened pipe, with failure coming later due to the initial injury. Though at this point, with no one so far pointing out in earlier heavy work, I'm every day more inclined to also think old, beyond end of life pipe.

    *Are you familiar with the pressure on 30" CNG trunk lines?
     
  14. Sep 12, 2010 #13
    If my memory serves, it's around 1000psi<absolute>. I'm far more familiar with 12" tees and 2*" transport lines. At the junction between the 30" trunks and 12" lines it gets to around 1100 psi. The thing is, I know it drops to around 60 psi at secondary transport, and then below 1 psi for homes...

    You mentioned familiarity with construction and the like... do you have more accurate info? I'm working from memory here, and with pipes from 12-42 inches, and pressures from 1100-1/4 psi I'm losing track here. I also don't know what interchanges would have been in the area... was that trunk line servicing these homes, or just transport pre-development?
     
  15. Sep 12, 2010 #14

    mheslep

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    Yes w/ familiarity with commercial construction and procedures for digging, no to CNG pressures.
     
  16. Sep 12, 2010 #15
    OK, I'm going to do some research and see if I got the numbers right then. I can confirm .25 psi for home inlets, with pressure of 65 psi going into that interchange. The junction at a 12" -> 30" line is 1100 psi, but.... I suspect the sustained pressure in a 30" line is MUCH lower. I know it requires boosting along the way due to loss of transmission speed to friction... the exact pressure at the midpoint of a 30" inch line, I need to check on.
     
  17. Sep 12, 2010 #16
    OK, here's some info... http://quasiturbine.promci.qc.ca/QTGasPipelineValentine0508.htm

    and here we have an analysis of a prior accident, which states that the max operating pressure for a 30" trunk line is 1200 psi. Sounds like it can be as low as 250psi to 1200 psi.

    https://www.mms.gov/PDFs/1993/93-0039.PDF [Broken] (bad security cert, but it IS safe, scanned by Avast!)
     
    Last edited by a moderator: May 4, 2017
  18. Sep 13, 2010 #17
  19. Sep 13, 2010 #18
    A sewer line was installed over the gas pipe in 08. The gas pipline is under a roadway. This was a disaster waiting to happen.

    http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2010/09/11/MNB91FCDGK.DTL

    I hope I got the right link.

    Just the gasline

    http://www.sfgate.com/cgi-bin/object/article?f=/c/a/2010/09/12/MNB91FCDGK.DTL&o=0 [Broken]
     
    Last edited by a moderator: May 4, 2017
  20. Sep 13, 2010 #19

    mheslep

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    Yes, that earlier sewer work was exactly the kind of thing I had in mind, doing damage that could cause a failure in old pipe or new:

    Rewelded? How could that have possibly been done in a residential area without disrupting the entire neighborhood?

     
    Last edited by a moderator: May 4, 2017
  21. Sep 13, 2010 #20
  22. Sep 13, 2010 #21
    This doesn't sound good!

    OOPS here is the link.

    http://www.twincities.com/ci_16054084?nclick_check=1
     
  23. Sep 13, 2010 #22
    Wow... PG&E is going to be sued so hard their investors are going to get bloody noses. No wonder they were so quick to take responsibility; that's easy compared to what sounds like gross negligence.

    mheslep: They can shut off gas to a region of pipe and send in a welding robot... I don't know if this is what happened however. Even if others placed a sewer line over this trunk line, PG&E is ultimately responsible. This is a disaster that they had better settle out of court if they have brains; a jury would crush them with punitive damages.
     
  24. Sep 13, 2010 #23

    Ivan Seeking

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  25. Sep 14, 2010 #24
    About half way through this ABC news video clip it shows a diagram of how the pipe was welded together in sections to make a turn. It also had a section with a horizontal weld the length of the pipe.

    http://abcnews.go.com/US/san-bruno-...on-pipelines-run-homes-safe/story?id=11628120

    It was probably state of the art at the time (1956).

    One thing puzzle me. How did it get enough air to cause an explosion under the pavement and with dirt on top of it?? The crater was 160 ft long 25 ft wide and 8 ft deep.
     
  26. Sep 14, 2010 #25
    I doubt it did. I've heard the sound described as, "the sound of a hovering jet at medium altitude, then a whooshe, and double boom."

    To me this indicates a rupture in the line which reached the surface, but didn't ignite... probably one which took time to reach the surface if reports of a smell of gas-additives are true. Once that ignited, you probably had a small (and hard to see) flame, which at some point traced back to the pipe. The first "dull" explosion was the pipe blowing underground, and the second was... well... the explosion everyone saw.

    This is just my opinion, but it's a valid chain of event which takes into account witness statements, and answers your question. Of course, I could be COMPLETELY wrong... caveat emptor! :wink:
     
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