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Gas Explosion is the worst I have ever seen

Tim McElwain
Tim McElwain Member Posts: 4,648
in THE MAIN WALL
in my 50 + years:

<a></a><ol><li><a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOngfDadccfCFvXl?format=standard">Huge gas-line explosion rips through San Francisco suburb</a>

<a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOmUfDadccfCuXSm?format=standard"><img src="http://cdn.smartbrief.com/images/stories/jhboom24.png" width="150" height="87" alt="" /></a> YouTube/The Associated PressA huge fireball erupted in a San Francisco suburb Thursday night, destroying nearly 40 homes by one count and killing at least four people. The explosion, which triggered a fireball that filled an entire street, was apparently caused by a ruptured high-pressure natural gas line operated by Pacific Gas and Electric, although company officials cautioned that the cause of the blaze hadn't been determined. <a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOngfDadccfCFvXl?format=standard">[u][color=#0000ff]The New York Times (free registration)/The Bay Citizen (San Francisco)[/color][/u]</a><span style="color:#666666"> (9/10) </span>, <a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOnsfDadccfCRojO?format=standard">[u][color=#0000ff]Google/The Associated Press[/color][/u]</a><span style="color:#666666"> (9/10) </span>, <a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOmUfDadccfCuXSm?format=standard"><img src="http://www.smartbrief.com/images/briefs2/common/sourcelogos/i_video.gif" width="25" height="16" alt="" />[u][color=#0000ff]YouTube/The Associated Press[/color][/u]</a><span style="color:#666666"> (9/10) </span><img src="http://cdn.smartbrief.com/images/briefs2/common/sm_share.gif" width="34" height="14" alt="" /><img src="http://cdn.smartbrief.com/images/shim.gif" width="4" height="4" alt="" /><a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOtEfDadccfCjQjE"><img src="http://cdn.smartbrief.com/images/briefs2/common/linkedin.gif" width="14" height="14" alt="LinkedIn" /></a><img src="http://cdn.smartbrief.com/images/shim.gif" width="2" height="2" alt="" /><a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOtQfDadccfCkAuX"><img src="http://cdn.smartbrief.com/images/briefs2/common/facebook.gif" width="14" height="14" alt="Facebook" /></a><img src="http://cdn.smartbrief.com/images/shim.gif" width="2" height="2" alt="" /><a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOucfDadccfCmFcY"><img src="http://cdn.smartbrief.com/images/briefs2/common/twitter.gif" width="14" height="14" alt="Twitter" /></a><img src="http://cdn.smartbrief.com/images/shim.gif" width="2" height="2" alt="" /><a href="http://r.smartbrief.com/resp/yfpwdojnmkdbsOuofDadccfCqejL"><img src="http://cdn.smartbrief.com/images/briefs2/common/btn_email_story_gray1.gif" width="45" height="14" alt="Email this Story" /></a> </li></ol>

<strong></strong>

<strong><span style="font-size:12pt">Today they stated that a weld may have come apart. very unusual as all welds on a 1,000 lb pressure transmission lines are x-ray tested at time of welding.</span></strong>

Comments

  • CWS
    CWS Member Posts: 17
    Someone Smelled Gas?

    The way the earth shift in that region of the U.S. I wouldn't be surprized if the pipe ripped from earth quake movement. i thought I heard somewhere where someone mentioned smelling gas hours before ignition. Hmm?
  • Tim McElwain
    Tim McElwain Member Posts: 4,648
    There has also been a mention

    of some sewer work having been done in the area. I am sure when all this settles down they will come up with a cause. The NTSB handles these investigations along with DOT. That is because gas travels interstate through large high pressure transmission lines. They actually in this case built houses to close to the transmission line.





    As you travel you will notice right of ways with electrical transmission lines above ground. In those same areas gas transmission lines are below ground in these so called "right of ways". Most states have strict requirements as to how close you can build to these and even for farmers how close they can plant crops.



    Many years ago we had a farmer in Mass shear of the top of a blow off on one of these lines fortunately it did not cause any explosion or fire just scared the farmer half to death.
  • Tim McElwain
    Tim McElwain Member Posts: 4,648
    Here is some more info
  • CWS
    CWS Member Posts: 17
    Xray

    What's the protocol on the welds. I thought the state has a rep xray each weld before signing off.
  • Tim McElwain
    Tim McElwain Member Posts: 4,648
    That is correct all

    welds are x-rayed and a number is assigned to each weld and they are kept by the transmission company.
  • Glen Aspen_2
    Glen Aspen_2 Member Posts: 53
    testing is very stringent

    as well as the xray procedure the entire line would have been hydrotested as well. As Tim states each weld is recorded on a weld map that includes location and welder that did the procedure. I would also give some consideration to changing ground conditions that can cause corrosion; the weld fill material acts like an anode (gives up ions) and the pipeline acts like a cathode (receives the ions). If the cathodic protection failed then the first failure point is the weld.
  • Tim McElwain
    Tim McElwain Member Posts: 4,648
    Some more information:
  • Timco
    Timco Member Posts: 3,040
    Age

    Pipe was installed in 1956. What is protocol for inspection? Pressure test sections? Not feasible to dig it up and inspect it all the way from end to end. What will happen here do you suppose?
    Just a guy running some pipes.
  • Tim McElwain
    Tim McElwain Member Posts: 4,648
    All gas lines are

    subject to a survey inspection on a pre-determined schedule. In addition this is why odorant is added so that the general public can become part of the survey. If you smell gas you never enter a building and you call the gas company or fire department.



    Most piping is also corrosion protected with anodes which are also monitored on a frequent basis to insure the integrity of the piping.



    There is no control however over out side construction damaging piping and failing to report the damage.



    This particular pipe is also in an area that has frequent earthquake activity so I would hope a more intense survey schedule would be carried out.



    When you look at all of the pipe in the ground carrying all kinds of volatile substances we have a fairly good safety record here in North America.
  • Tim McElwain
    Tim McElwain Member Posts: 4,648
    More information
  • Tim McElwain
    Tim McElwain Member Posts: 4,648
    The latest information
This discussion has been closed.

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