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Thread: Metal pipe joint

  1. #1
    Associate Engineer
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    Metal pipe joint

    Hi dear colleagues,

    i have to find a way to connect two metal pipes 30mm diameter without a thread.
    Those two pipes are a part of a ore drilling machine, they are rotating and vibrating, so i need strong joint and in the same time it has to be dissembled easy and quick

    Regards,

  2. #2
    Administrator Kelly Bramble's Avatar
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    Well, without threads you could design in a shear pin. Depending on the wall thickness you may be able to include a locking feature.

  3. #3
    Administrator Kelly Bramble's Avatar
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    Seems like in most down-hole applications folks use ACME Stub type threads...

  4. #4
    Lead Engineer Cake of Doom's Avatar
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    How about a bayonet type fitting? I thought threading was pretty much standard for these types of things.
    Last edited by Cake of Doom; 04-25-2013 at 03:27 AM.

  5. #5
    Lead Engineer RWOLFEJR's Avatar
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    Do you have I.D. or O.D. restrictions... or would adding anything inside or outside of the pipe be a problem? How quick is quick for disconnecting? Any flamable gas? Is it just these two particular pieces or many of them? What is the pipe doing or its purpose in the arrangement?

  6. #6
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    If it is ore drilling, you need a positive method of driving it. A shear pin type of thing will do just that, shear. The constant load/unload condition of drilling will quickly wear anything but threads. The oil drilling industry knows what it is doing and has been doing it for a hundred years and some things have not changed, namely the pipe connections. That's gotta tell you something.

    If you have 1,000' of pipe hanging off each connection you need a strong and positive drive or you are going to leave 970' of pipe and an expensive drill head down the hole. Especially so if you get a cavern break-through and the pipe is suddenly hanging on all the connections.

    Good roughnecks can change in/out a 4" oil well pipe in under thirty seconds. Just how fast do you need to go. Train the humans!

  7. #7
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    Quote Originally Posted by RWOLFEJR View Post
    Do you have I.D. or O.D. restrictions... or would adding anything inside or outside of the pipe be a problem? How quick is quick for disconnecting? Any flamable gas? Is it just these two particular pieces or many of them? What is the pipe doing or its purpose in the arrangement?

    Basically we have pipe with O.D of 32mm with wall thickness 3.6mm. We have water that have to pass inside the pipe for cooling. It have to be disconnected quick (more or less for 1 minute) with bare hands. We are doing core sampling, which means we dig ore and there is no gases included, just solid material. We have to connects multiply pipes with 1.5m length and get 30 m long connection of pipes.
    If you need any additional information, be free to ask..we are really stuck and we need urgent solution of this problem.

    Thank you in advance,

  8. #8
    Lead Engineer Cake of Doom's Avatar
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    Thread the outside of the pipes and use a collar to join them. But unless there is additional information/restrictions that we haven't been told about; you're asking for a solution to a problem that was solved yonks ago. As seen here:-

    Quote Originally Posted by PinkertonD
    Good roughnecks can change in/out a 4" oil well pipe in under thirty seconds. Just how fast do you need to go. Train the humans!
    Good luck

  9. #9
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    Cake 'o' Doom, that was a desperation bid, training the people. The guy should be using standard 15-deg or 18-deg oil drill pipe tapered threads. I guess they are looking for a magic-fix as my suggestions seem to be falling on deaf ears. Damn, I failed Magic-101.

  10. #10
    Lead Engineer Cake of Doom's Avatar
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    I should have picked up on the desperation .

    I have seen some of the previous magic test papers. You're not alone in failing those modules.

  11. #11
    Lead Engineer RWOLFEJR's Avatar
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    Hi Vektor...
    There's more than one way to skin a cat, but it does seem that you might be trying to reinvent the wheel so to speak. But I'm no stranger to that so I'll jump right on in here feet first.

    I need tell you a little story first.
    We had a big job opportunity here at the shop for a customer product and we needed a CNC lathe with a good sized hole through the spindle. Little over 5". We were financially sound enough and could've borrowed the quarter million bucks + and just bought a brandy spankin new machine for the job but we've always been pretty cautious about spending money. The parts we were producing were light tubular components and the huge Okuma's with the big hole were designed to spin heavy parts. We didn't need the weight or radial capacity and we really could use a higher rpm machine to turn the shafts journals. So what we did was buy an old used LC20 and plucked the headstock off of it. We redesigned the guts and Voila!! We had a high speed big hole double chucked machine. After a little testing and tweaking we modified a second machine so we wouldn't get caught with our pants down should anything happen to the first. That was about 20 years ago and we still run them today. I have several other stories just like this one but the point is... in that instance we spent about 70,000 per machine when we could've gone the easy way and spent about 250,000 each. So we got the job done and not the way everyone else on the planet would've...

    I'm no expert in drilling or gathering core samples (or much of anything else for that matter ) but maybe somebody out there is indeed using some other means of connecting their pipe? And if they aren't... So what? It's fun to try to come up with different ways to skin cats. Hypothetical cats that is...

    That's a pretty small pipe you're dealing with and since you're only going down about a hundred feet you might be able to connect some other way? Maybe 4 to 6 pins in a push and twist set up similar to an automotive turn signal bulb? Maybe milled lugs on the tube ends that look like a spider coupling... a ridge behind those lugs and a clamp on sleeve to keep them aligned? Maybe two keystone shaped lugs and slots 180 degrees apart that would allow you to slide the two butted together ends together and then again a clamp or lock collar to keep them aligned. The keystone shape allowing to both lift the assembled rods and apply some torque... and the sleeve or lock collar to keep them aligned.

    Or picture a tube for your home sweeper with the little spring loaded button to hold them together but put a male and female shape on the tube ends to drive them? Maybe a male and female hex or spline shape on the tube ends to drive and a simple push pin to keep them together and allow the lifting?

    Another thought crossed my mind and is why I mentioned gases... Small as these are maybe just butt weld and then sawzall as you pull them back up?

    Equipment for deep drilling is pretty expensive. If you're not in that business or not doing many core samples I could see where a person might try to find a less expensive way to get it done if your not going deep and a failure wouldn't be a catastrophic loss in time or equipment. Drill rod is high dollar stuff. X-rayed and tested to the umpteenth degree. This is to reduce severe losses from a rod breaking after you've put hundreds of thousands of dollars down the hole.

    Reminds me... We used to make a device for retrieval of broken drill rod for a very large drilling company. They were pretty slick. Worked like a Chinese finger trap.

    Anywho... there are some alternatives that might spark some idea for you.

    Good luck,
    Bob

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