I am building a project that uses several joints of 1 1/4 " galvanized pipe, including elbows and Tee's. The unit will be plumbed into my 50 psi water system. What is the best way to seal the pipe joints? I have assembled the unit and tested using teflon pipe dope and had several leaks.

The teflon wraps should be at least 5 and up to 10. I use 8 on most threads. It also needs to be tight enough.

Doesn't the directions say 2 layers? I like Pipe-X by Loc Tite. I find it in auto parts stores.

Like Labman, I give the threads a couple of wraps of Teflon Tape with the threads. Some plumbers use more but two wraps is the minimum. Regards, btom

It has been my experience that most plumbers I have spoken with use 5 wraps. I went to 8 or 10 when I had leaks on the top of a water heater with 5 wraps. I absolutely do not get leaks with 8 wraps and I get the joint very snug but not cranked. If 2 works for you then I am OK with that for you. I get teflon tape for 19 cents per roll. I can afford to splurge. [smilez]

1-check to insure the threads are continuous without chips and gaps that occur when you use cheap pipe,cut threads with dull blades creating bad threads.
2-wrap threads with quality teflon wrap, some wrap is rated for gas (yellow) and some are thicker then others, I use a good quality thick wrap with a couple of wraps around the threads in a clockwise rotation for right handed threads and visa versa for left handed threads, this keeps the teflon wrap from unwrapping when you tighten the joint.
3-Then to be sure I use a teflon paste also around the tape I don't like leaks because its just too time consuming breaking joint apart and doing them again & again. So spend the extra $ use quality products and take all precautions

I'm not a big fan of teflon tape.

La-Co Slic Tite is pretty much the only thread sealant I use anymore.

When I was managing a factory, my guys weren't much at pipe fitting. The one could do oil tight welds. I picked up a head for our threader that would cut the grooves for Victaulic style couplings. That cut our oil dry bill way down.