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out of curiosity.....

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  • out of curiosity.....

    what is the theory behind using lead and okum to join cast iron pipe? why is it not welded? just curious!


  • #2
    First off this method of joining CISP (Cast Iron Soil Pipe) pre-dates electricity and welding machines existed so that is one good reason

    Also, once you've done a few hundred of them you can go pretty fast. I'd bet I could caulk more lead joints than a welder could in the same time and not have a leak.

    Also, cast iron pipe is not easy to weld, and like other cast iron shapes requires pre-heating to avoid cracking the pipe. CI pipe was not made from the best of materials years ago, i.e. usually from scrap iron and were cast in sand molds. It was not too uncommon to get a fitting with a sand hole in it or one that was much thinner on one side than the other, the same happened with pipe which was cast in 5 foot lengths and later in 10 footers, these short lengths were in part driven by the weight of the pipe and what a man could safely (safety, did they have that back then?) handle. Production methods have improved greatly in the past 20 years and this is rarely happens now, but you can run across some of these lesser quality fittings in existing installations. Back in the early 1900's we (the USA) were not the dominant manufacturer of steel and iron products, I have seen many fittings still in service which were menufactured in Germany by KRUPP and others.

    You can find more here on the history of CI Soil Pipe;

    Cast Iron Soil Pipe Institute


    And BTW, one of the biggest repeat safety violators in the country is Tyler Pipe and its sister company McWane. McWane has killed or injured more workers than all their competitors combined. DO a google search on "McWane" or read this story on the PBS web site;

    Bob D. (fixed some typos)

    [ 05-12-2004, 08:52 AM: Message edited by: Bob D. ]


    • #3
      Excellent post Bob, lead and oakham dates back to shipyard uses where it was used to repair hulls way back in the pirate days. It really is a very successful way of sealing imperfect surfaces, I come accross alot of cast iron oakham piping dating back 80+ years and it is still in service and preforming quite well.

      With welding you require two perfect mates, and since pipe creation at the time it was widely used was un-uniform at the best of times, it would require alot of fabrication and grinding where as lead and oakham is an excellent material for filling large and uneven gaps common in the old hub and spigot cast iron.

      [ 08-14-2004, 04:10 PM: Message edited by: Ghostfitter ]


      • #4
        ooh rah for bob d real informative


        • #5
          Aside from the reasons why lead and oakum joints were used the theory as to why it works is when the oakum comes in contact with water it swells and creates a water tight seal. The leading of the joint is not to prevent leaking but to give rigidity to the piping.
          Len<BR>Midlantic Plumbing & Heating