Threading pipe in general

Paul Mitchell

Was having a "heated" discussion today with a plumber. From when I was a pup always was told....."Threaded pipe is correct if you get 3 turns onto the threaded pipe with a fitting..then tighten with the wrench." Has always worked for me. Am I crazy or what. Plumber said he "threads 'em deep" So he lets it go so you get the threads into the fitting.
Since we are on the subject say we were to thread 3"...Same deal with amount of turns?

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Andy Morgan_2

I was taught

by my father that a properly threaded pipe will have three threads showing when tightened into a fitting, on all sizes. Also, there is a certain number of threads per size of pipe. For some reason, 13 threads for one inch pipe
(I think) sticks out in my mind.

Andy Morgan

R. Morgan Mechanical, LLC

Big Ed

Thread

I run it to the end when the dies open or with a non adjustible , when the pipe reaches the outer face of the die holder....

Tony Conner

3 Turns...

...hand tight. Don't wrench it up so fast that the friction generates too much heat. (Like jamming a wrench into a Ridgid 300 and using the machine to tighten the fitting onto the pipe.) If you're threading large (2-1/2" to 4") pipe with a Ridgid 141, it's marked where you're supposed to start & stop.

We installed a 150 HP steam boiler that runs at 125 PSIG, ran the feedwater lines (170 PSIG) to that boiler, and replaced the feedwater lines to a 300 HP boiler, ran a bunch of condensate, chemical feed, etc as part of a big job (for us) last year. I'll bet there was a thousand threaded joints, and there was two leakers. One of them was a fitting with crappy threads.

Three turns to hand tight. I've used it on 300 PSIG steam lines, and it works.

Kevinj

ASME codes

The ASME has a table with the specifics on thread engagements based on pressure and pipe size. It seems that a 1" high pressure is 7 threads engaged but it varies with diameter and pressure.

Frank_15

300

whatsa wrong with tightened them with the 300? I do that all of the time ad never had a problem

Tony Conner

The Old...

...Audels Plumbers & Steamfitters books from the 20's caution against tightening fittings up too fast. The newer Audels books say the same thing. You can generate heat from friction, and get leakers, especially on high pressure steam. It's also very easy to overtighten fittings, using the machine. To me, there are things you always do - like reaming the pipe after it's cut, and things you don't do - like using the threading machine to tighten fittings. I know there are lots of guys, in lots of trades that use the machine for tightening fittings. I don't ever remember seeing a steamfitter do it though.

Big Ed

Tony

You mean hand tighen the fitting and then three turns with a wrench ?


P.S. I admit I have used the machine now and then...

Terry St.James_2

Don't want to sound to technical about threading but myself have always adjusted the machine to give me 3 1/2 turns by hand and 4 1/2 when threading stainless steel. But you guys should know by now where to stop on the dies...
1/2" & 3/4" should have 14 threads when completed
1" to 2" should have a total of 11 1/2 threads
2 1/2 pipe should have 7 1/2 threads and 3" pipe should have 6 threads
And ...you guys do not use a machine to tighten the fittings on the pipe...jeez...if not for safety reasons...think what work you have to go through if there are changes and you have to get that fitting off again. Please don't tell me you use the machine for that too?

DaveGateway

threads

I believe I read in a plumbers hand book "3 complete rotations of a fitting is considerd a made up joint" {minimum}

Tim Gardner

A not-yet-dead old man (85 years old) told me you could use the machine to get them off. He never mentioned putting them on that way, though.

Mark Wolff

3 turns

3 turns by hand and then tighten with a wrench. You are absolutely right. Some people never do understand tapered threads. As for tightening with the threading machine, I confess to doing it regularly, but after the info posted here on it, I may not do it so often.

Big Ed

Guilty as Charged

Yes Yes , I confess I have used the machine for tighting up fittings .And your right I did not care for the future fellow that might have to remove that fitting. I only thought of my selfish satisfaction ease of the moment . There , there I said it, I feel better and will only look ahead of the thread from now on . I am a reformed machine tighting -it-upper....... I promise !


Merry Chrismas fellow Wallies and to the health of your Familes..

Tony Conner

You Just...

...need to use the "3 turns by hand" rule to check the initial die setting, especially on the adjustable die heads for 300's and 535's. (The drop head die setting should be checked whenever the dies are replaced.) You should get between 3 & 4 turns by hand, with no tape or dope on the threads. The length of the thread should be the same as a factory nipple of the same pipe size. Once the dies are set for a given pipe size, it's not necessary to check every thread. And once you've got the dies set properly, and T-Tape or the right kind of dope for the service on the threads, you shouldn't have to kill yourself to get a leak-tight joint with the right sized wrench.

It also helps if you lay out the work so that you're doing end to centres, and you tighten a fitting on one end of the pipe in the tristand, where you can use your weight on the wrench. This cuts the number of times you have to wrench something in place, in half.

Tony Conner

I Didn't Really Answer Your Question

Once the dies are set, you just screw the fitting on, as far as is comfortable, by hand, then wrench it. I've never really counted the wrench turns. I stop where it feels right, and the tee or elbow is pointed the right way. It shouldn't need to be SO tight that you can't make minor adjustments to square/true things up after they're installed.

bob young

make - up methods

the problem with making up a fitting by machine is only when you lock the pipe wrench under the handle . if you hold wrench and release when it feels tight enough you will have no problem.a little risky for some one who is not well acquainted with a machine but i have been doing it for so long i know no other way. it is simply a time and back saver.it is a rather dangerous profession any way you cut it.