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Pipe math
Bill Nye_2
Member Posts: 538
For a 45° offset multiply by 1.415. I have a few books lying around. Check Dan's reading list or try this link to books and more on this site.
http://www.heatinghelp.com/shopcart/product.cfm?category=262
http://www.heatinghelp.com/shopcart/product.cfm?category=262
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Comments

Measuring pipe offsets and angles
I usually have a difficult time calculating offsets and angles for piping whether it is piping in pvc for 90 percent system, running black iron for a gas line or piping in copper for a boiler. I use the trial and error method, eyeballing it or dry fitting it for pvc pipe. I find trial and error very time consuming, and eyeballing it and dry fitting can be time consuming but more importantly not very accurate. Any tips or rules of thumb you guy's can share would be greatly appreciated? Also, is there any books or videos that explain how to calculate offsets and angles that you recommend that would help me out in the field? Thank you in advance.0 
Yes there are books out there to help with the job at hand unfortunately I don't have them here at home but will have access to them on Tuesday this coming week. There are a few formulas to give you the right measurements for them offsets and angles. Any work needs basic tools for measurements other than the obvious measuring tools squares, levels and a plumb bobs are a great investment,not to mention all the different style lasers out there. Get with me next week and I can give you the authors of the books I have. Just about every way of doing things can be found in these books and they are relatively cheap. EMail me at noframeofmind@comcast.net if interested.0 
Dan sells an old speedily tool here
i used to have one of them many years ago. it was made of card board and came in a small size and a gert size. look about in his store i think you can find one.
The "Speedily " tool is called a Rocket at Dans Shop.0 
Go to
Dan's Reading List (on the navigation bar above) and scroll to Pipefitter's Math Guide by Johnny Hamilton. It's a book that will help you so much. And if you buy it through HeatingHelp.com, Amazon will send some money to New York Cares. Costs you no extra. Thanks.Retired and loving it.0 
45 degree offsets
A 45 degree offset is really very simple to make, once you know the method.
Picture a square box with a line drawn diagnally from the lower left to the upper right corners. The diagnal line is the same as the travel(T) part of the offset. The sides are the offset (O) and the top to bottom are the rise (R).
To calculate the length of the travel (T), multiply (R) or (O) X 1.414 Because this is a square, (R) and (O) are exactly the same dimension. Remember that all of your measurements are taken from center to center. You must take off the fitting allowances before you cut the pipe.
Conversley, if you already know the travel measurement you can determine the rise and or the offset by multiplying the travel X .707..
T = R X 1.414..
T = O X 1.414..
O = T X .707..
R = T X .707..
O =R0 
A Lot Of Guys...
... don't know how to get that first number that they then need to multiply by 1.414. That's the key to the whole process. You need to find a common reference plane from where you are, to where you're going, so you can figure the centre to centre dimension. You can use a wall, floor, ceiling, existing pipe, or duct. A laser level works great too, especially if you're in the middle of a big space, like a warehouse.
Say you're running parallel to an existing wall. The pipe is 12" from the wall to centre of your hangers. The line then has to jog around some obstruction  structural column, duct, sprinkler line, etc. If the same wall runs past this obstruction, that works nicely. Measure off the all to the centre of your next set of hanger rods. Say it's 22". The 45* offset will be 22"  12" = 10". Multiply the 10" by 1.414, and now you have the centre to centre for the travel piece. Take away for two 45* elbows and cut your pipe. Remember that there are different "take away" values for each size of pipe, and the kinds of joint you're working with. Screwed joint take aways won't be the same as Vic, or copper, or butt weld, etc. even for the same size pipe. There are tables in piping books that will give you the take aways for each style of fitting, or the info to figure it out. In any event, you can do a couple of measurements & subtraction in the field, and get the number you need.
For vertical offsets, use the method with the floor, ceiling, etc.
If you're dealing with smaller offsets, just lay them off on a framing square. The example I used would mean 10" down the blade & tongue, and measure diagonally across the two points. Works like a charm  then just subtract the takeaways. Remember to use the outside OR inside increments both points on the framing square  don't "mix & match". For bigger offsets, you can lay the square off against the corner of a room, tool box, etc  anything with a 90* corner that's big enough.
Remember  the key to the entire process is to get that first pair of measurements for the centre to centre distance between where you are, and where you're going. Subtract the smaller number from the larger, and there's the value that kicksoff the rest. Once you have that, the rest of the process pretty much falls into place, with a little bit of practice.0 
math and stats
Not to knock any of the above posts, I would recommend The Pipe Fitter's and Pipe Welders Handbook [its pocket sized]by Thomas W. Frankland. It's crammed with formulas and tables and can be kept in the trucks glove box.0 
piping angle offsets
I was able to dig through my pile of stuff. I found this chart that I developed when I was teaching. The key is to using it is to know one of the 3 measurements, "T" "O" or "R". The rest of the job is to multiply the known factor by the indicated constant for each of the various angle.0 
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CALCULATING OFFSETS
I hope the attachment has attached itself.
This is the angle calculation chart that I devised when I was teaching apprentices. It utilizes the time tested and reliable constants that were developed by the dead men many years ago. The measurements are from center to center. After you calculate the length of any side of the offset, take off the proper fitting allowances. Your result will be accurate to within .001 of the unit of measure: inches, feet or even cubits.0
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