PVC drop pipe: male adapters vs threading the pipe

[Paltus]

This isn't a BMW so that manual does not apply. You asked if there was an industry standard to prevent pipe unscrewing in submersible pump installations. There IS and I quoted that standard. Franklin electric that invented submersible motors and sells millions of pumps and motors has published that spec in their AIM manual for decades.

NAPCO that makes threaded pvc drop pipe says 1" will handle up to 1.5HP AND 1.25" will handle up to 2HP. They say use dope NOT tape and torque to hand tight plus 1 full turn.

I'll admit that's not very scientific so I shoot for the published specs I know to work.

thanks I appreciate it

 

[Jeff H Young]

I like the Comments a very simple subject and I have over 30 years in pipe trades but never well work .
Cary has his proven method , which I'm not familiar with but respect experience. I just can't be comfortable tightening till it pops dry ha ha its like chalk squeaking on the board. It does seem to be a weird way of assembly but if it works every time and never ever a failure , good enough I'd say. I'm guessing if the threads let a few drops past and dripped a little no ones ever going to know.
normally especially something I'm not 100 percent at ease with I like to follow specs when available I'll use torque specs on automotive

 

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[Valveman]

Finding good help in the pump business is hard because the job is miserable. We use to go through over a hundred new hires every year, just to keep 18 people on full time. Needless to say I trained many new hires every year. Tightening the pipe was one of the easiest things to teach. Just tighten until it pops a couple of times and quit. Never had a problem, even with a new hire doing it every day. As VA said NPT won't seal on its own. The silt, sediment, and rust will get in the thread and stop the leak. Same as when plumbing with galvanized pipe, just let it drip for a day or two and it will seal on its own.

 

[Jeff H Young]

Finding good help in the pump business is hard because the job is miserable. We use to go through over a hundred new hires every year, just to keep 18 people on full time. Needless to say I trained many new hires every year. Tightening the pipe was one of the easiest things to teach. Just tighten until it pops a couple of times and quit. Never had a problem, even with a new hire doing it every day. As VA said NPT won't seal on its own. The silt, sediment, and rust will get in the thread and stop the leak. Same as when plumbing with galvanized pipe, just let it drip for a day or two and it will seal on its own.

VAwelldriller said same as you as far as the joint sealing itself (don't know how you determined that it does seal , or that it matters if it seals off 100 percent?) whether it drips a day or 2 or forever no one knows or cares I would think .
I trust that your advice is sound Cary, I notice VAwelldriller saying he dopes his fittings.
On non well/ pump work I've done tons of plastic to metal threads and mine can't leak at all even a drop. normally I dope and tape. but its not subject to a pump torqueing.

 

[Valveman]

There are lots of ways to skin a cat. Everyone has their own method. If I worked for VA I would do it exactly like he told me, because I know he has tested it many thousands of times. No question it does come apart easier with paste.

You can tell if it is leaking because you lose pressure over time when no water is being used. With the little pressure tanks you can tell very easily, bigger tanks not so much. But still if it comes on in the middle of the night every once in a while you know there is a leak somewhere. The rust in galvanized fittings makes them seal off fairly quickly. But it might take a while with stainless, so I can see where dope may help.

I guess the point is that its not rocket science. Just get em screwed together. Lol!

 

[Jeff H Young]

There are lots of ways to skin a cat. Everyone has their own method. If I worked for VA I would do it exactly like he told me, because I know he has tested it many thousands of times. No question it does come apart easier with paste.

You can tell if it is leaking because you lose pressure over time when no water is being used. With the little pressure tanks you can tell very easily, bigger tanks not so much. But still if it comes on in the middle of the night every once in a while you know there is a leak somewhere. The rust in galvanized fittings makes them seal off fairly quickly. But it might take a while with stainless, so I can see where dope may help.

I guess the point is that its not rocket science. Just get em screwed together. Lol!

No not rocket science and good point some guys do a little different, I like to be aware of these things, thanks for bringing up if it leaks down pressure will drop not being familiar I thought a check might be involved . Wells aren't common at all where I work. I've probably worked on a house with a well but cant remember ever having done so. its that uncommon for me. still like to hear how they work

 

[Paltus]

in the mean time I am glad to report that threads made with $13 PVC threader online look so much better than threads made with an electric threader for metal pipe, that I am finally warming up to the idea of threading the pipe for this application.
Will keep posting other test results here

 

[Jeff H Young]

in the mean time I am glad to report that threads made with $13 pvc threader off Amazon look so much better than threads made with an electric threader for metal pipe, that I am finally warming up to the idea of threading the pipe for this application.
Will keep posting other test results here

Good to hear, yea them expensive 13 dollar chinesium dies are the best!

 

[Paltus]

I will measure it in ft/lbs for PVC+SS dry, for factory threads on the adapter and for DIY threads on the other end of my test pipe,
and will post it

At 57.4 N-m the pipe made a sound like a very quiet little girls fart or something. I don't know if that's it or not but feels like a lot of torque for pvc
( them little girls ... ).
Thats what my DIY socket for 1" tees looks like after putting two onto two ends of a test pipe. I won't measure the 2nd pop with it...

Galvanized 1" tees to sch 80 pipe, dry, ~75F

 

[Reach4]

At 57.4 N-m

which is 42.3 ft-lb.

 

[Jeff H Young]

you are putting all the plastic fittings together dry? or just what is on the drop pipe?
I would think your "goodntite "

 

[Paltus]

you are putting all the plastic fittings together dry? or just what is on the drop pipe?
I would think your "goodntite "

this is a short test pipe, one side (shown) has glue welded male adapter, the other side has DIY threads on the pipe. I am going to put this test pipe under load test and see which side fails first.
I didnt put any thread sealant or tape onto this test pipe. I am still thinking about how to do the real drop pipe.

 

[Valveman]

That is a grey male adapter. I don't know how that should sound. But white sch 8o threaded pipe sounds more like a big girl fart. Lol!

 

[Jeff H Young]

this is a short test pipe, one side (shown) has glue welded male adapter, the other side has DIY threads on the pipe. I am going to put this test pipe under load test and see which side fails first.
I didn't put any thread sealant or tape onto this test pipe. I am still thinking about how to do the real drop pipe.

Great just a test well let us know I'm interested.
I'd go with the threaded SCH 80 pipe if at all available (even though this out side my line I never set a well pump) But Like the experience Carey has a little nervous trusting the pop but he didn't invent the technique its been around I heard about it from other guys on PVC threads.
I hope your test is good and gets a good straight pull , but again from a non well guy I trust threads way more than PVC glue.

 

[TheOverThinker]

Threading pipe cuts away half the pipe thickness so, it cuts the pipes pressure rating in half. Glued joints have a higher pressure rating, but less weight holding capacity.
The torque from a pump starting tries to unscrew the pump from the pipe. Rapid cycling has unscrewed the pipe and dropped many a pump in the well.

Does it work to thread AND glue the threads?

 

[Paltus]

Does it work to thread AND glue the threads?

you'd normally use rigid PVC pipe with metal ( SS ) female adapters so PVC glue won't help. Other type of glue may help but
can make it difficult to undo without cutting pipe if you need to pull the pump later on. but if you don't need to pull the pump
in a long time and/or don't mind cutting pipe then it doesnt matter I guess so I don't see why not, just a bit not practical

 

[Jeff H Young]

ok paltus keep us posted on the stress test how many pounds to break male adapters and glue joints vs threaded pipe just a interest , but since you are doing it please share

 

[John Gayewski]

There is no "recommended torque" there is a minimum thread engagement that need to be made up. Which means if you don't have that many threads inserted before the seal is formed then you have something out of spec. range.

We usually wrap tape around the threads leaving the very first thread with no tape on it. Then use the tape spool to work the tape into the bottom of the threads. Then fill the taped threads with dope. Then run the threads tight until the tape is no longer visible (smaller pipe this doesn't quite get there). When the tape disappears your can feel your tight.

Keep in mind here plastic pipe can be threaded but threading procedures were not made for plastic pipe. The procedure described above is meant for black iron or galvanized pipe. Tape can prevent you from getting the minimum number of threads inserted before your tight, thus causing a plastic fnpt joint to split.

Threading plastic pipe was a bit of an afterthought compared to threading iron pipe. Whatever indicators are used to show a sealed secure joint the number of threads is what's at issue. You need the surface area of a number of threads to keep the joint secure. Very little to do with tightness.

I'm not a well guy. The swinging torque issue would be something novel and specific to that situation. I would think the minimum thread engagement would need to be increased for something like that.

 

[Paltus]

ok paltus keep us posted on the stress test how many pounds to break male adapters and glue joints vs threaded pipe just a interest , but since you are doing it please share

Finally got to do this experiment. went upto 1500 pounds, held for 5 minutes and nothing broke, neither the threaded end nor the glued adapter.
That's the max the neighbor's tractor can do so I am afraid it will conclude the measured experiment for now.
Maybe I will try a 20 ton hydraulic jack next but will never know how much it actually takes to break ...
Feel a lot more confident about both glued adapters and threaded pipe ends now !

 

[John Gayewski]

Finally got to do this experiment. went upto 1500 pounds, held for 5 minutes and nothing broke, neither the threaded end nor the glued adapter.
That's the max the neighbor's tractor can do so I am afraid it will conclude the measured experiment for now.
Maybe I will try a 20 ton hydraulic jack next but will never know how much it actually takes to break ...
Feel a lot more confident about both glued adapters and threaded pipe ends now !

A properly glued joint is a type of weld. It should hold whatever the pipe will hold. Most joints are not properly glued.