Welding concrete lined pipe

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Has anyone had any experience welding concrete lined pipe?.I had a call out Friday afternoon to weld a 8" water main that a rubber flange had let go on, I ended up welding two joints as the company's new practice it to weld not replace the rubber. The pipe was 8" in dia and 1/4thick with a 1/4 thick concrete lining. It had a fairly thick bitumen coating on it.I had good access from the top and one side but the bottom and other side I only had about a foot add a bit as someone had built a pump shed almost on top of it, and it had a large rock under it.It was the only supply line for three towns so it had to be done ASAP.It welded pretty well for a pipe that I was told had been 3 feet under the ground for about 55 years.Simonhttp://members.optusnet.com.au/~abba/index.html
Reply:My first thought is tht the company requesting this sort of repair has to be a bit crazy.    The primary reason being that wet concrete blisters and explodes when heated.     That is why a good safety officer will not allow torch work and welding to take place directly on a concrete floor.     Considering this is a concrete lined pipe that concrete should be very wet at the time of welding.Now the question is did enough heat get into the pipe to damage the concrete.    I suppose they could also repair the concrete after you weld the pipe up.    In any event if you exposed the steel of the pipe by blistering the concrete, that pipe will be subject to either rust and corrosion or occulation at that point.It would be interesting to see how the water company makes out with these repairs down the road.    Obviously it is one of those things that work great for the moment.    There may also be this idea that the pipe is 55 years old and beyond its lifetime so any problems the repair might create will be avoid by future planning.   Sounds like a ncie job in any event.    As long as you are gtting you pay I wouldn't worry to much.Dave
Reply:weird, never heard of concrete lined pipe.   Ive dealt with pipe lined with concrete, but not on purpose.  Ive found its possible, but best with a 6010 rod, and you gotta burn it hot and fast, careful for porosity though.  SOunds like yhou did alright.   Thanks for the storyIF it Catches...Let it Burn
Reply:Our water district here has many miles of concrete encased pipe. Starts out at the source (lake) as a 48"er. That's one point I'll emphasize, encased (outside), not lined (inside). Hits the tank(s) then exits as a 42" for miles then reduces, and reduces and reduces. All put in in the early sixties by the Bureau of Reclamation. All joints, risers, saddle taps and other connections were originally welded. Everything down to about 10" or 12" was originally concrete encased, then they used several grades of pvc, ductile and transite as well. But now there is a hodge podge of whatever scattered thoughout the system. I only know of two locations where they deploy cathodic protection, they may have more, I dunno. The local guys do talk about the difficulty of repairs, which are rare. They don't do the actual welding themselves but hire it done when required. Bust off the concrete, get all the tar and paper off somehow, weld, re-goo the whole thing and pour a three bag mix back over it. Can't say how they handle simple repairs like holes punched in it. Probably a simple compression collar (spelled $$$$).
Reply:Find someone who works at a refinery, they deal with concrete lined pipes all of the time.  Plus, it's really important that their pipes don't leak.
Reply:When I had thoughts of leaving my ATV at our ranch I was thinking of ideas to make it theft proof, or at least make them work hard to steal it.  So I wanted to make a cage for the ATV and line all the 2" pipe with CONCRETE so they would have a harder time cutting the pipe.
Reply:I have no experience with concrete lined pipe, but did have to demolish a concrete lined hot water storage tank in my apartment building a decade ago.  It had lasted 80 years, which is pretty good for a steel tank.  Compare that with the 5 or 10 year longevity of today's glass-lined water heater tanks.The concrete is for corrosion prevention (or,at least, delay).  The lining is not waterproof, but, as I understand it, the oxygen in the water that permeates the liner and ends up next to the steel eventually is consumed by combining with the steel.  After the oxygen is consumed, the corrosion stops.  The oxygen depleted water then forms a protective layer preventing further attack by fresh, oxygen-laden water passing through the tank/pipe.  Apparently there is not much interchange of depleted water with the fresh water due to the limited porosity of the concrete.  You can still buy concrete lined tanks at a premium price.  And, of course, the concrete is not just your sidewalk patching concrete from the home center.The upshot of this is that I think the water company is building itself a bunch of booby traps where future corrosion will be very much quicker at the welds than in the concrete lined sections of pipe.  They may have made some financial analysis justifying their policy, and you would hope that they know what they are doing.  But I'll bet it is just false economy and rank ignorance in action.awright
Reply:I think they do have a long term plan in place to replace the whole line but at the time if it was not repaired three towns would be out of water in a few hours depending on usage as it took the company boys a while to find the leak.Where I welded it was the flange which did not have concrete on the bell end on one pipe but it was on the inside of the pipe that pushed into the bell,like the Diagram below._______________/''''''''''''''''''''' < no concrete in the join''''''''''''''''''''''''''''''''''''''''==========  ================================Concrete lined to here                            ,,,,,,,,,,,,,,,,,,,,,,,,==========================  ================Concrete lined pipe""""""""""""""""""""""""\,,,,,,,,,,,,,///weldSimonhttp://members.optusnet.com.au/~abba/index.htmlLast edited by welder.man; 05-21-2006 at 05:50 PM.
Reply:welder.man,They must have just ripped the old rubber out then you welded back? A lot of gap to fill or pretty tight?Just thinking about it, even the threaded portion of galvy rusts out in 15 to 35 years depending on the soils. What you welded starts rusting today but it'll be a looong time before it has to be dealt with again. Lot of water districts will look at the age of the existing facilities and gauge the repairs accordingly.
Reply:There are thousands of miles of welded concrete lined pipe delivering water in the U.S. It's very common.JTMcC.
Reply:Originally Posted by welder.manI think they do have a long term plan in place to replace the whole line but at the time if it was not repaired three towns would be out of water in a few hours depending on usage as it took the company boys a while to find the leak.
Reply:I used AS/ANZ E4110-2 (pipe arc 6010P) I guess a 5F PF was the position.The gap was 1/4" at the top and about 5/8" at the bottom as the pipe had dropped and the company did not want to re lift it as they thought in may do more damage. I don't know how many rods I used as I don't count them anymore.Simonhttp://members.optusnet.com.au/~abba/index.html