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Bill Nye_2
Bill Nye_2 Member Posts: 538
They didn't know it was there! Sometimes you just gotta' call before you dig. Safety first CYA


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  • GaryDidier
    GaryDidier Member Posts: 229

    It is very lucky no one got hurt. Thank God.

    Gary from Granville
  • JimGPE_3
    JimGPE_3 Member Posts: 240
    No fun...

    I have a buddy who works for the local gas company. He's the guy they send down in the hole to "stop the hissing." He will weld a patch onto a high pressure gas line while the line is still leaking. Yeah, he's nuts.

    A professor in college taught us about upper explosion levels: gas won't explode if it is more concentrated than a certain parts per million (the upper explosive level), but I wouldn't bet my life he knew what he was talking about!
  • mr ed
    mr ed Member Posts: 26

    I was working at Prudhoe Bay when an equipment operator tore into a 2 inch gas line with a ditch witcher, laid open a 2 inch gash. The foreman had us clearing permafrost and rock from around the hole with pick axes in subzero weather. Talk about a pucker factor! Don't like the leaky gasssss! - Mr Ed
  • Welding on a live gas main

    is an art. It can be done if all safety factors are applied.

    As far as natural gas you have to have the correct gas/air mix for ignition to take place. This can be determined by using your Combustible Gas Indicator which every gas man carries. All plumbing and heating contractors should have a CGI meter for there own safety.

    What is the mix? The Lower Explosive Limit is 4.5% gas with 95.5% air, the Upper Explosive Limit is 14.5% gas with 85.5% air. What that means is gas between 4.5% to 14.5% will ignite or explode depending on conditions. The rules are if gas level is below 4.5% you VENTILATE if above 4.5% you EVACUATE. You also must try to eliminate sources of ignition. If you do not have a meter you should not enter buildings were you smell gas. These same gas perimeters are what are needed for proper gas combustion.

    The levels for LP gas (propane) are different the LEL is 2.15% to 9.6%.

    One of my first experiences with natural gas in a trench was working with a welder as his helper. Someone up the main opened the wrong valve and his torch ignited the gas which flashed over our heads and scared the hell out of both of us. We had the good fortune of having it iginite above us and not in the trench. I have been present when an explosion took place and it is a scary experience.
  • Larry (from OSHA)
    Larry (from OSHA) Member Posts: 716
    They were lucky

    Yes, do the One Call thing before digging, hand dig within 2 feet of markings. Safe trenches and so on. This very same action caused a major explosion and fatalities a few years ago here in Minnesota. Blew up a whole block, if I recall correctly. More recently, a gas explosion was determined to be the result of improper fittings on plastic piping. That one leveled a building and killed a few people. Our gas utility is now beginning the process of inspecting and replacing something like 35,000 fittings around the state that were apparently all installed by the same contractor. Can you smell liability? (not quite the same as mercaptin)

    Larry (from OSHA)
  • singh
    singh Member Posts: 866

    That reminds me of the time when I "pimped" for a welder at JFK Airport in NY.
    Where they store all of the jet-a fuel is call a tank farm and the gas tanks have underground piping from tanks to terminals, except its bare black iron pipe. JFK is built on a marsh, so the salt content in the soil erodes and pits the piping, they lose quite a bit into jamaica bay.
    The port authority decided one run was losing too much so we had to patch it.
    10' deep pit, fuel soaked soil, and one way out.
    I cut the 8" pipe by hand using pipe cutter,pump the remaining fuel out we then packed the pipe with dry ice to displace the oxygen levels, slide a 8" x 15' "dutchmen" in place and weld the joints in before the ice melts and we go kaboom! Scary!!! now that I think about it.
    This little job took two weeks, and the weld joints had to be x-ray certified, that means I had to grind out the slag after each pass,sparks flying all over. To make things worse it was 20 degrees outside a week before x-mas.

  • Jay_17
    Jay_17 Member Posts: 72

    2 months ago a house in my neighborhood (about 200 feet away) blew up from a NG leak. The owners smelled gas outside, called the company and they sent a guy over. He checked out inside the house and found nothing, started probing around the underground gas pipe, apparently hit a pocket of gas. Apparently the buried gas line was broken by a truck driving across the lawn, now the house was filling up.... He got the owners out, and the next-door neighbors, was moving behind his truck when the gas hit the boiler and blew, demolishing the house. The ensueing fire badly damaged two adjacent houses. The only injury was the gas man who was knocked down and had a bit of a nervous breakdown.
    A good warning.. And a good job by the gas guy.
  • Dale
    Dale Member Posts: 1,317
    Classic case

    I think the culprit in Minn. is bad pipe, a very old PE, a version that fails catastropically at the joints. I think the area was owned by a former propane co. that must have got a good deal on the pipe and didn't want to dig it up so they sold the system. Every time we have bought a system from a propane company or municipality we have to rebuild most of it. Contractor I know is one of 4 going up there to replace those, I have heard thousands of services. As to safety the outside gas smell is almost always more dangerous than the inside one because of the pressure involved and not knowing where the gas really is going. Your worst day is the smell and a directional drilling machine out working in the street. In Wisc. most utilities won't go into a building if the gas at the door is 1% or more, approx. 20% of the LEL, we shut off the source and naturally ventilate. Like Timmie we used to be more bold but realized the fire dept won't go in without full turnout gear so we have become more cautious. We have alot of valves and use them much more than we used to. Human life is the key, not the cost of relighting.
  • When gas man checked

    inside the house he failed to follow correct procedure. Shut off all possible sources of ignition. If he had done that the boiler would have been off and possibly no explosion.

    I question also of he had the house blow soon after he arrived and did not find anything in the house how did the level of gas build up so fast? Was he using a combustible gas indicator to test or was he using his nose?
  • Jay_17
    Jay_17 Member Posts: 72

    Details have remained a bit sketchy, he clearly should have shut everything off first. I have heard that he was not very experienced, the guy who should have been on call that day was out for some reason. I know this because my father in law worked for the power utility and found out things through channels.
    I wonder what the insurance settlement will be?, havent heard anything about that yet.
This discussion has been closed.