Pipe Threading Tips

Last time we talked about the fines that could be imposed by spilling cutting oil on the ground while threading pipe.  I have still not found the agency in California that is responsible for enforcing that law but I have a lead, so I will keep you posted. 


This time we will talk about threading your pipe by hand as most handymen or handywomen do not have access to an electric pipe threader.  After you cut your pipe with the appropriate pipe cutter you will notice that there is a ridge that formed on the inside of the pipe due to the way the pipe cutter works, the pipe cutter does not actually "cut" the pipe in the sense that a hacksaw cuts but it forces the metal apart and pushes down with such force that it is shearing the metal and the metal that is near the inside diameter is forced inward.  That ridge has to be removed to improve the flow of whatever you are going to introduce into the pipe, whether it be a gas or a liquid.  What will happen if you don't remove the ridge is that you will get a turbulence that forms and that will impede the flow.  If you fail to remove the ridge in all the pipe that you cut and thread, you could possibly decrease the flow volume in half or more depending on how many seperate pieces of pipe you have in your system. 

They make a pipe reamer that will remove the ridge and create a slight inside bevel that helps with the flow characteristics to improve the efficiency of your piping system.  If you are doing just a few pipe threads there are other tools that will also do the job, one of those being a deburring tool, which is a small handheld device that has a screwdriver like handle and a hardened steel cutting tip that is shaped in such a way that when you rotate the tool around the pipe, the hook shaped end rides on the inside of the pipe and the cutting edge removes a slight amount of the metal ridge with each turn of the handle.  It is quite a handy tool to have around the shop.  The other option is to use a rat-tail file and a bit of elbow grease.

Once you have the inside of the pipe reamed out it is at this point that you want to carefully look at the outer edge of the pipe to see if it flared a bit when you cut the pipe, this can happen if you are too aggressive or if the cutting wheel of the pipe cutter is dull.  If the end has a slight outward flare to it, it will make it difficult to get the pipe die started cutting your threads.  If you need to flatten out the end of the pipe to get rid of the flare, the only way that I found that works effectively is to use a flat file to file down the flare.  I tried using a handheld grinder but that took off too much material in an uneven pattern and the pipe die did not want to start evenly.

Now that you have your pipe prepared for cutting the threads, clamp the pipe in your pipe vise with about 6-12 inches sticking out and tighten down the vise with a reasonable amount of pressure as you don't want the pipe to rotate while cutting your threads.  Place a bucket underneath the end of the pipe to catch the Thread-Werkz that drips off from the threading process.  For this step, I like to wear gloves and my gloves of choice are pigskin.  I buy mine at Rainbow Bolt and Supply in Riverside, Ca. and they will ship to you.  They are very reasonably priced and hold up quite well, I keep one pair just for pipe threading as they can get quite messy.  I even use them for welding gloves.  Now you are ready to start cutting threads.  Make sure you have your bottle of Thread-Werkz ready and squirt about a half ounce onto the end of the pipe, take your pipe threader with the proper size die and slide the end with the smooth part onto the pipe about an inch (at this point the cutter will make contact) and you will have to push the end of the pipe threader with one hand (this is where the gloves come in handy) and rotate the handle in a clockwise direction until you feel the cutters "bite" the pipe.  Sometimes it will take a few turns and pushing harder on the end of the pipe threader to get it to bite, once you feel it bite you still need to keep pushing the threader onto the pipe to make sure the next cutters bite into the pipe.  Once you are sure that the cutters are started on the pipe, squirt more Thread-Werkz onto the cutters and rotate the pipe threader about one more complete turn.  At that point, it will get increasingly harder to cut more threads so what you need to do is to rotate the pipe threader in a counter clockwise direction about a 1/2 or 3/4 of a turn.  What this does is clear the chips from the threads that you had already cut and creates a clean path for the cutters to keep cutting new threads, once you feel the thread chips break away (you can feel it in the handle, kind of like a click) reverse the knob on the threader and rotate in a clockwise direction until you feel resistance.  This is when you want to squirt more Thread-Werkz onto the pipe and the cutters.  Repeat this process until the end of the pipe is even or sticking out a little bit from the end of the pipe threading die.  Unthread the pipe threader from the pipe, loosen the pipe vise and rinse the end of the pipe with water to wash of any residual Thread-Werkz left on the pipe from the threading process.  This is a major benefit of Thread-Werkz vs. the thread cutting oil that is available.  If you are threading pipe for a water system and use oil to cut your threads, it will take a very long time and a lot of water flowing through the system to flush out the taste and smell of the oil.  Not Thread-Werkz, rinse with water and you are done!