Help! Mandrel will not go through pipe!!!

[yanert]

Hello,

We are having problems getting 4" mandrels to go through long rad. sweeps!! Has anybody has this problem?? Its just in the sweeps and they are buried underground in concrete. (concrete encased ductbanks) I have talked to my supplier and he has mentioned that Cantex PVC has been banned in many areas. He is going to research what type was used on this job. Has anybody had problems with this before? Could they have enough egg to do this? I am wondering if maybe they could be getting gummed up between the coup and sweep. (they have male ends on both sides) Any suggestions? Short of modifying the mandrela on the largest rings, it looks like we could be screwed. I know the installation has good quality as I have taken pictures on the runs and also inspected them before the pour. It just looks like maybe I should have inspected the sweeps a little bit better. You get busy and your guys are blowing and going, I guess this could be a big lesson. I have thought about soap but it will just gum up the pipe for the next contractor. The mouse goes through just fine but not the mandrel and the specs call for two passes and a signiture sign off. Anyhow, thanks for any advice and remember, it might be a good idea to run your mandrel through before you bury or encase, or at least drop a mandrel throgh the sweep before you install!!

 

[rick5280]

Re: Help! Mandrel will not go through pipe!!!

I have never heard of this procedure. Could you explain it in more detail, or furnish a link to some info?

Thanks

Rick Miell

 

[iwire]

Re: Help! Mandrel will not go through pipe!!!

Rick, it is just a device to verify a conduit is clear of obstructions before pulling cable.

Flexible Steel Mandrel
Used in extremely bent conduits, the Hardened steel disks of graduated sizes are strung on flexible steel cable. This mandrel efficiently clears obstructions from the conduit.

If a customer hires one contactor to install the underground conduits and expects to use a different contractor for the conductor installation they may want to witness the mandrel making it through the conduits to verify that they are clean, continuous and not crushed.

This should prevent finger pointing if the cables can not be pulled through the raceway.

yanert

You are in a world of hurt, it sounds like the sweeps are egged to much for the mandrel, I would suggest finding out the maximum size mandrel that will pass and hope the engineer will agree that is enough space.

You also might have another sweep of the same type you used shipped to the job to try the mandrel in it, I know the 90 is not cheep but you have a big expense ahead if you can not satisfy the engineer.

Bob

 

[flightline]

Re: Help! Mandrel will not go through pipe!!!

All of our new underground conduits are SCH 40 PVC with GRC at the ends. iwire is showing the forgiving mandrel. We have to use the wood

test mandrel or the aluminum test mandrel or slug. This is a link to a manual on mandrels. This is a link to a short FAQ on mandrels.

I can understand how PVC bends will have deformity in their walls that is fairly visually undetectable. That being said, you still have a problem. They do make a flexible plastic mandrel, [both Condux & Greenlee]. Perhaps it's a longshot, and a bunch of work, but you could grind the circumference of the largest disk, and when it passes, measure it. Perhaps the customer will accept a slightly smaller conduit diameter if the difference is small enough. Just a longshot. I guess you have little to loose.

I have to agree with iwire again as you will be in a world of hurt if you are held strictly to the mandrel test without any relief. I doubt if the manufacturer of the sweeps will pony up a backcharge, but if you can prove defective materials, out of his published tolerance, who knows. They might try to shift the blame back to you, stating that you should have checed, but I tend to be cynical.

There are many times where we hace ductbank placed under one contract or project, and later go back and pull the conductors or fiber under another.

I wish you luck and hope that some of this helps.

 

[lrollo]

Re: Help! Mandrel will not go through pipe!!!

Yanert, I am sorry you're having a hard time. I know it wont help you this time around but maybe you could, in the future, get a variance in the specs to use rigid ells instead of PVC. I have fought tooth and nail with engineers about this and I personally wont budge without a sign off from a engineer stating he will pay me to change the PVC to rigid if there is a problem. Again, I am sorry youre having trouble. I wish you all the best luck in getting it fixed. Have a great day, leamon

 

[yanert]

Re: Help! Mandrel will not go through pipe!!!

Hey guys, thanks for the advice, one thing that has me thinking. We are using a schedule 20 pvc that is rated only for concrete encasement. I did not use a schedule 20 sweep, I used a schedule 40. Also, if the mandrel is for rigid and Imc, I wonder if schedule 20/40 pvc has another mandrel. I need to read that mandrel link. Thanks again!

 

[frenchelectrican]

Re: Help! Mandrel will not go through pipe!!!

we are using a shedule 20 pvc that is rated for encased conctete encasement

you mean sechedule 20 that is very odd ball item i ever heard but maybe i am wrong but i know shedule 20 is very thin wall pvc and most of contractors use 40 and 80 and some case 120 but majorty use the rigid conduct sweep up that what many place asked for it

i just want to understand that clear

merci marc

 

[don_resqcapt19]

Re: Help! Mandrel will not go through pipe!!!

yanert,
What will be pulled into these conduits? I'm not aware of any listed schedule 20 conduit for use with electrcial conductors. Telephone utility conduit is often schedule 20.
Don

 

[yanert]

Re: Help! Mandrel will not go through pipe!!!

Hi Don,
I will check on that for you.
We are working for a very large contractor and all the PVC has been provided for us. Tens of thousands of feet. It is Schedule 20, and it says right on it, use only for encasement in concrete. I will check on it some more!

 

[yanert]

Re: Help! Mandrel will not go through pipe!!!

Don,
I has a brain freeze for a minute. All the concrete encased schedule 20 is for communication Ductbanks. Most will have innerduct pulled into it. None will have highvoltage. Thanks!

 

[flightline]

Re: Help! Mandrel will not go through pipe!!!

I've never heard of Schedule 20, but I have heard of types "EB" and "DB". I searched Carlon's website and on page 30 of their catalog I did find a type EB-20. It says that it is designed for concrete encasement and rated for 90 degree conductors. Huh. This link to a FAQ for a number of different non-metallic conduits, that might be unfamilliar to most electricians. Don might be interested in this since there is something about listings and a link to an ETL White Directory [??]

The fact that you are using Sch 20 with Sch 40 bends, while kinda' odd, may weigh in your favor, since this is what you wer supplied by others, perhaps your customer or their agent. You did what wou were told.

lrollo too is correct that a nylon type rope with even a moderate amount of pull, and so sidewall pressure, cut and weld itself into the wall of a PVC conduit over a period of pulling. But you installed a system designed and specified by others, and have to meet their requirements.

I hope the information and links help.

 

[dogcircuit]

Re: Help! Mandrel will not go through pipe!!!

Hi Don,
Yes I have had this problem before!!!! Normally the mandreling is required by the local utility to verify the conduit has not been crushed or damaged. In our area all sweeps are required to be sch 40 and when I have trouble pulling a sch 40 mandrel most inspectors will allow me to use a sch 80 mandrel which is a little smaller in diameter "This usually does the trick" Hope this helps

 

[jrdsg]

Re: Help! Mandrel will not go through pipe!!!

another non-sequitor, but i have a couple of friends that work for a large ec in ca. they tell me that there are guys down there that have done nothing but install underground pipe for their entire careers.

is this for real?

 

[yanert]

Re: Help! Mandrel will not go through pipe!!!

Hi Dog,

So there is different mandrels for different schedules of pipe! I called two different greenlee reps yesterday and they thought they were all the same. The mandrel that I am using is rated for all Rigid and IMC. I asked two reps if they had a mandrel designed for just schedule 40 or 80 PVC, they said its all the same! Anyhow, I will do some more checking. Also, yes, its called schedule 40 DB and schedule 20 EB. Thanks guys!