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Thread: cast iron sewers

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    Default cast iron sewers

    I have been using a sonde for this application with 512 hz. Many times I will put my sewer machine down the line and cannot unstop it due to a collapsed pipe. I put it back in, unplug it, and try to trace it out. With it being cast and in the ground I find myself locating everything up and down the street except the sewer, everything else. What do you guys do?

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    Conservative Meanie ifinditunderground's Avatar
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    Default Re: cast iron sewers

    There isn't much you can do unless you can hook directly to the pipe, or induce a signal onto the pipe from the surface. When you insert fishtapes or sondes into metallic pipes you more often than not will get a cancelling of that signal. I believe it's called "Gauss Theory", or something similar.
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    Default Re: cast iron sewers

    I suppose 83 kHz would be best on it like the water main?

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    Conservative Meanie ifinditunderground's Avatar
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    Default Re: cast iron sewers

    The higher the better. But you need some wattage behind the frequency as well, if it is possible.....
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    Default Re: cast iron sewers

    Quote Originally Posted by ifinditunderground View Post
    The higher the better. But you need some wattage behind the frequency as well, if it is possible.....
    I only have a 5 watt transmitter, we will see next time.

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    Default Re: cast iron sewers

    83khz is going to bleed off even worse I would think???? I agree with IFIND ...hooking up to the actual iron pipe is the only way to go ....try 33khz with higher wattage pushing from the transmitter.
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    Senior Member Turk182's Avatar
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    Default Re: cast iron sewers

    Is it cast iron all the way to the city sewer, or does it transition to clay or plastic at some time?

    Your best bet would be to send a sonde down the line and then locate the sonde.

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    Default Re: cast iron sewers

    Quote Originally Posted by Turk182 View Post
    Is it cast iron all the way to the city sewer, or does it transition to clay or plastic at some time?

    Your best bet would be to send a sonde down the line and then locate the sonde.
    It can be cast all the way. Sometimes it does transition at the road if coming from the home/business.

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    Senior Member Turk182's Avatar
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    Default Re: cast iron sewers

    Quote Originally Posted by Gettinit View Post
    It can be cast all the way. Sometimes it does transition at the road if coming from the home/business.
    Lead or gasketed joints? If a gasketed joint isn't pushed all the way home you will lose then signal at that point, for that matter if the pipe had a really good tar coating you could lose the signal from lack of metal contact. Tape a sonde to the end of a sewer rod and locate that, or get a sewer camera with a sonde built into the camera head.

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    Default Re: cast iron sewers

    Quote Originally Posted by Turk182 View Post
    Lead or gasketed joints? If a gasketed joint isn't pushed all the way home you will lose then signal at that point, for that matter if the pipe had a really good tar coating you could lose the signal from lack of metal contact. Tape a sonde to the end of a sewer rod and locate that, or get a sewer camera with a sonde built into the camera head.
    I have a camera with sonde. It can be a real slow process on a long sewer. I have had good luck with Jameson duct hunter with pvc and other non-metallic pipe but haven't tried it with cast yet. With the signal not carrying down my drain machines I wasn't too hopeful, but willing to try.

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    Default Re: cast iron sewers

    Quote Originally Posted by Gettinit View Post
    I have a camera with sonde. It can be a real slow process on a long sewer. I have had good luck with Jameson duct hunter with pvc and other non-metallic pipe but haven't tried it with cast yet. With the signal not carrying down my drain machines I wasn't too hopeful, but willing to try.
    I normally advise using a low frequency sonde when attempting to locate metal pipes. In cast iron 512Hz will probably be the best frequency to use. As you increase the frequency the signal will become weaker because the cast iron pipe will act as a shield to the signal. I aslo find that in steel pipes it is not possible to use any kind of sonde to locate the signal.
    I would be interested to hear if anybody out there has had any success on locating steel pipes using sondes.

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    Default Re: cast iron sewers

    Quote Originally Posted by Doctor Locator View Post
    I normally advise using a low frequency sonde when attempting to locate metal pipes. In cast iron 512Hz will probably be the best frequency to use. As you increase the frequency the signal will become weaker because the cast iron pipe will act as a shield to the signal. I aslo find that in steel pipes it is not possible to use any kind of sonde to locate the signal.
    I would be interested to hear if anybody out there has had any success on locating steel pipes using sondes.
    I have found copper water mains with Radio but have not tried it on galvanized yet.

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