Electron_Sam78
Senior Member
- Location
- Palm Bay, FL
Has anyone ever installed a surface mounted conduit run on the outside of a very large circular object such as a grain silo? How do you bend for that radius?
Large radius conduit bending
- Thread starter Electron_Sam78
- Start date
- Status
ultramegabob
Senior Member
- Location
- Indiana
you have to make a series of small kicks, there is a way to figgure out the spacing between them to get the radius, I dont have it memorized, the last time I had to do it, I think I used the Benfield conduit bending book.
masterinbama
Senior Member
- Location
- Huntsville Alabama
If its 1" and smaller I can usually hand bend it around the structure by securing 1 end and bending the pipe about every 6 "s or so using a piece of shallow strut or 1X lumber behind the pipe allowing you to overbend it for springback . Bigger pipe gets tricky but with some layout and a lot of 6 degree bends spaced properly it can be done. I have done it with 4" once before. The quickest way I know to find the distance between 6 degree bends is to divide the circumference by 60.
Last edited:
Kdog76
Senior Member
- Location
- The Dairyland State
I'm assuming you mean bending the conduit around the silo, not running up it.
What size & type of conduit will be used?
ultramegabob
Senior Member
- Location
- Indiana
ultramegabob
Senior Member
- Location
- Indiana
if your doing alot of large radius bending you might buy one of these....
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=99736
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=99736
Last edited:
JacksonburgFarmer
Senior Member
- Location
- Butler County Ohio
It depends...what size conduit, and what type??? PVC, just form it around the bin. Emt, can be done, if a large enough bin.....not always....
I have litterally run miles of conduit around bins....some PVC, although I dont like it....Mostly IMC or RIGID. Take your chicago, and do some practicing, dont take long to figure out.....
IF it is large conduit, I would consider trying to go underground around the bin....
Is this a grain bin or a Silo...yes there is a difference....A silo holds "wet" crop, and a bin is for dry. If you dont know, ask the farmer. Why do I ask??? If it is a bin, and you have to go very far around the bin.....here is a trick....
Most bins have a drying floor. This floor is elevated about 12" off the concrete base. This is how the ventilation works....anyhow, you can drill a hole in the side of the bin, under the floor, and run your conduit under there....you will have to assemble your conduit outside the bin and push it across as you go....the trick is getting it back out the other side....YOU MUST COMPLETLEY SEAL THESE HOLES BACK UP THOUGH!!!! or the ventiallation wont work right....There will be "chairs" that support the floor under there also, so be prepared to fight those.....I have only done this once.....but there was no other way to get there.....
I have litterally run miles of conduit around bins....some PVC, although I dont like it....Mostly IMC or RIGID. Take your chicago, and do some practicing, dont take long to figure out.....
IF it is large conduit, I would consider trying to go underground around the bin....
Is this a grain bin or a Silo...yes there is a difference....A silo holds "wet" crop, and a bin is for dry. If you dont know, ask the farmer. Why do I ask??? If it is a bin, and you have to go very far around the bin.....here is a trick....
Most bins have a drying floor. This floor is elevated about 12" off the concrete base. This is how the ventilation works....anyhow, you can drill a hole in the side of the bin, under the floor, and run your conduit under there....you will have to assemble your conduit outside the bin and push it across as you go....the trick is getting it back out the other side....YOU MUST COMPLETLEY SEAL THESE HOLES BACK UP THOUGH!!!! or the ventiallation wont work right....There will be "chairs" that support the floor under there also, so be prepared to fight those.....I have only done this once.....but there was no other way to get there.....
Cow
Senior Member
- Location
- Eastern Oregon
- Occupation
- Electrician
Underground is best if possible. Otherwise, two of us hold the emt against the grain bin to form it, but you'll have to use the bender to get the ends bent enough. You may need a couple little bends in the middle too, to help it fit a little better. If the tank is empty, usually a guy will jump inside and hold the 5/16" nuts while the outside guy zips the bolts out. Then use the bolts to hold your strap.
Greg Swartz
Senior Member
- Location
- Colorado Springs, Colorado
I had to install some lights for Rock Bottom Brewery on a grain silo. I used 480's suggestion: lots of straps. (I even helped things along by adding a small angle to the conduit too...) But when I put the straps in, I used a tek screw with a rubber bushing, to keep the weatherproof seal for the grain silo.
For small pipe bending it in place works.
If it's big pipe there is a mathematical formula on how to do it in this book:
http://www.coxco.net/Electrical_Books_s/3.htm
I've never tried it but everything else in this book seems to work fine.
If it's big pipe there is a mathematical formula on how to do it in this book:
http://www.coxco.net/Electrical_Books_s/3.htm
I've never tried it but everything else in this book seems to work fine.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I seem to recall there is some way to do this with one of those fancy greenlee hydraulic pipe benders.
Red Wiggler
Senior Member
It amazes me how far the electrical trade has moved away from Quality and Craftsmanship to Quantity and "if it works its right attitude". Nowadays if a Foreman askes an average worker to install a pipe or conduit run in a situation that requires "concentric bends" most of them would find a way to get it installed, but the end results may not be physically attractive to the eye, might take some experimental time, and could possible generate a small pile of scrap pipe.
But if the Foreman had asked a worker that is proud of his trade, its heritage and respected the fact that what he has to offer is his "skills", "intelligence", and his "experience", that person would be salavating like a mad dog for chance to make those bends.
I don't want to sound like I am critizing people that don't know how to do a rarely used method of bending pipe,(and I guarantee that there are many pages of written text on how to bend pipe concentrically) it's just that our trade is drifting so far away from what it used to be. This "drift" is caused by economics and the never ending quest for faster, more, and "I can't see it from my house attitudes". This same thing must have happened to the Egyptians...They built fantastic structures that have lasted for eons, but I don't think there is a person alive today that can actually tell you how it was done(skills, techniques). Our skills are fading. We are becoming nothing more than installers, we are losing skills that used to keep the Electrical trade at the vanguard of the construction trades.
But if the Foreman had asked a worker that is proud of his trade, its heritage and respected the fact that what he has to offer is his "skills", "intelligence", and his "experience", that person would be salavating like a mad dog for chance to make those bends.
I don't want to sound like I am critizing people that don't know how to do a rarely used method of bending pipe,(and I guarantee that there are many pages of written text on how to bend pipe concentrically) it's just that our trade is drifting so far away from what it used to be. This "drift" is caused by economics and the never ending quest for faster, more, and "I can't see it from my house attitudes". This same thing must have happened to the Egyptians...They built fantastic structures that have lasted for eons, but I don't think there is a person alive today that can actually tell you how it was done(skills, techniques). Our skills are fading. We are becoming nothing more than installers, we are losing skills that used to keep the Electrical trade at the vanguard of the construction trades.
- Location
- Massachusetts
Bottom line, customers get what they are willing to pay for.
Perhaps... but somewhere along the line, contractors have automatically assumed the customer does not want quality craftsmanship over what is economically advantageous. IMO, most customers do not even know what level of craftsmanship they will be getting at the bid stage. All they see are dollar signs at that point. The industry itself has set the course for diminishing craftsmanship, not the customer.
ohm
Senior Member
- Location
- Birmingham, AL
True, managers don't even want to know what is or was involved and won't care about the end product, unless the customer complains or witholds payment.
Unless the customers raises an issue, the guy who did it cheapest is the winner.
- Location
- Massachusetts
Well we will remain in disagreement here. In my experiance the common situation is we bid a print as drawn, lets say all EMT. The customer gets the bid and gets sticker shock. Then they want the price dropped without loosing any visible features so the only thing that can go is the unseen stuff. So the EMT is replaced with MC, the hours to get it done are cut. The better fittings and equipment get replaced with whatever is cheaper the day of the pricing. The well written specs get overlooked in the name of the bottom line.
I do not disagree with you on this aspect. However, this has nothing to do with craftsmanship...
Say the customer went for the EMT. How many contractors are going to have their JW's run concentric bends on exposed conduit racks, when it isn't in the spec's to do so? IMO, the contractor is just as guilty as the customer regarding diminishing crafstmanship!
When MC is opted for over EMT, how often is it run "as the crow flies" in concealed areas, versus square to the structure. I'm not saying every contractor does this, but the ones that do contribute to diminishing craftsmanship.
Last edited:
The last time that I bent a piece of conduit to go around a silo (or tank), I was working for a machinery manufacturer that had a set of pipe rollers. They could roll up to 4" sch 40 pipe:smile:.
I would cut a pattern out of card board (about 3' long) with the desired inside radius and have the shop roll the needed amount in 10' sections.
After they got the rollers set correctly, the rest was easy.
You could probably do the same thing with a set of hydraulic pipe benders, but it would be tedious if you had a lot of pipe to bend.
That set of pipe rollers from Harbor freight looks like it would work OK on smaller sizes.
There may be easier ways.
Just a idea
steve
I would cut a pattern out of card board (about 3' long) with the desired inside radius and have the shop roll the needed amount in 10' sections.
After they got the rollers set correctly, the rest was easy.
You could probably do the same thing with a set of hydraulic pipe benders, but it would be tedious if you had a lot of pipe to bend.
That set of pipe rollers from Harbor freight looks like it would work OK on smaller sizes.
There may be easier ways.
Just a idea
steve
ohm
Senior Member
- Location
- Birmingham, AL
How true. I was told by a large speedway that they wanted to rewire their office but the bids they got were too high. The spec. was EMT but very little was run to a central location so MC looked like a good bet. I bid w/ MC and explained the difference to the owner.
Yea you guessed it he shopped my number, I lost a day doing the estimate and lost the job. Don't know how many times the job was shopped.
- Status