Pipefitter Math Made Clear

The travel is 15 9/16". The cut is 10 5/16". Now check it before the saw touches the pipe.

A cut piece of pipe is thirty seconds of saw time and twenty minutes of rework. This book is about getting the number right the first time, and about the thirty-second check that proves it - with a tape and a framing square, on the layout table, before anything is committed.

The geometry was calculated by one program and independently checked by a second. The second one does not know the first one's formulas: it rebuilds the pipe run as vectors in space, adds them, and measures where the far end lands. Across every worked example the two close on each other to better than a ten-trillionth of an inch. Figures printed as tape fractions are rounded separately to the nearest sixteenth, and manufacturer-dependent dimensions are marked as values to confirm on the fitting.

What is inside

• The four numbers - offset, run, travel, take-out - and the one sentence that ties them together


• Simple offsets at every fitting angle, with the constants and where they come from


• Rolling offsets taken apart one piece at a time: the true offset, the travel, the roll angle, and the mark you put on the pipe


• Cut elbows, mitered bends, and a 90 made from two 45s


• Wrap-around templates: angle cuts, ordinates, fish mouths, laterals and header holes


• Four complete jobs worked start to finish, including the one nobody writes about - what to do when the spool measures half an inch out and you have to find which number lied


• Reading an isometric, setting flange bolt holes, and the offset an eccentric reducer puts in your line


• Twelve reference tables at the back, and an index built from the real page numbers

How it is written

Every chapter opens on a job, works it in plain language, shows the drawing, and closes with a check you can do in thirty seconds. Thirty-eight chapters, thirty-three dimensioned figures, and no chapter that needs the one before it if you are standing at the pipe with a problem.

What it does not do

It does not replace the job drawings, the line specification, the welding procedure or the code. Where a dimension comes from a catalog rather than from geometry, this book says so and shows you how to get it off the fitting in thirty seconds. One table came out of the book entirely: three catalogs gave three different answers, so Chapter 4 shows you how to take that dimension off the fitting with a straightedge and a tape.

For pipefitters, steamfitters, welders, sprinkler fitters, apprentices, and anybody who has to turn a drawing into a cut length.