Home Depot cut & threaded iron pipe, but thread does not have taper

[ws6formula]

I am installing a compressor in my garage and running 1/2" black iron pipe. This is the first time I have ever installed black iron pipe. I went to Home Depot (HD)and had some 1/2" pipe cut and threaded to my required sizes. HD used a RIGID machine for cutting and threading. I am now test fitting all my connections. I am having some issues with the HD threaded pipe connections. For many of these HD threaded connections, I can only tighten the connection about 1-1.5 turns by hand. For the factory threaded pipe connections, I am usually able to tighten about 3-3.5 turns by hand. I checked the HD threads and they generally look ok. But, I noticed that the HD threads do not appear to have any taper. The factory pipe threads have a slight taper. I confirmed this lack of thread taper on the HD cut threads with my micrometer.
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I am speculating this lack of taper is preventing me from hand tightening any more than 1-1.5 turns. I read that I should be able to turn all connections approximately 3 turns by hand and then use my wrenches for approx. 2 more turns. After getting the HD connections 1-1.5 tight by hand, I am able to turn another 1.5-2 turns with my pipe wrenches.
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Is this a known issues with using a HD cut/threaded pipe? Does the RIGID machine not taper the newly cut threads? Will I be OK with hand tightening the HD connections 1-1.5 turns and then tightening another 1.5-2 turns with my pipe wrenches? Any other advice?

 

[jimvannoy]

Put some dope on them, tighten them up, and see if they leak.

 

[Lloydthumper]

It depends on how far up they thread them and how deep the dies are set most of the machines I have seen at lowes or home depot adjust themselves I have used a threader many many times and you have to play with them to get them the way you want it. Try Jimvannoy's advise and see if they leak I have put pipe together that fits just like you are saying and it has never leaked. You can use my bosses method of Tighten untill turns freely and then back off a 1/4 turn or his other method of tight as hell plus two turns. LOL. try it I think it will be fine to.

 

[Kevin54]

Or take them back and make them rethread them correctly. Pressured pipe has a taper thread for sealing purposes. http://en.wikipedia.org/wiki/Threaded_pipe Not all of the Yayhoos at the box stores know as much as they think they do. Before you leave the store, check fit with a factory ******, elbow, etc. I was standing at Lowes looking for some "B" vent and one of the clerks came up and asked if he could help me. I told him what I needed and he stated that they don't carry that. I had a piece of "B" vent my hand and asked him what this was. He said it was a flue pipe for a propane hot water heater.

 

[kbs2244]

I am guessing here, but rigid electrical conduit is basicly galvanized pipe.
The thread count and dia is the same but I do not belive it uses tapered threads.
They may have used the electrical dies instead of the plumbing ones.

 

[JB740i]

Hoped to do this same thing in the future, so I"m interested in the result.

 

[rockwithjason]

they have the wrong dies in the threader. you need a 1/8 taper die for that

 

[Flatmotor]

Make sure they have NPT segments in the die head and not NPSM which are straight electrical thread segments.

 

[rsanter]

its already been said, but I will chime in for a vote on wrong thread dies in the machine

bob

 

[ws6formula]

Thx for replies - I told the HD rep that was cutting and threading the 1/2" black pipe that I was using it for air. I was also buying a number of NPT fittings (ie. couplers, elbows, etc) at the same time. The HD rep told me he was a plumber.
I have assembled some of the HD connections (that lack the proper thread taper). I was planning to leak test a section at a time and see what are the results. Has anyone had any experience with using pipe connections that lack the proper taper? Am I likely to get air leaks? Should I just take the pipe back and get new pipe cut and threaded with the proper taper? (Note, I used Master Series Pipe Dope - asked for Rectorseal Pipe Dope and they did not carry it).

 

[nissan_crawler]

Personally, I would take it back and tell them to cut new pipe. Who cares if it does seal? It's still not right.

 

[Mr_fixit]

I can't understand how it can't be threasded correctly. All they do is thread PLUMBING pipe, not electrical pipe. My guess is that it's threaded correctly, But that you think it's not correct , since it's a little different than the prethreaded pipes.

Of course I'm usually wrong, just ask my wife.

 

[W-Cummins]

Well If they did have straight "Running" threads cut on his pipes he could turn them in all the way on, not only 1.5 turns. More likely they didn't cut the tapered threads long/deep enough.

William...

 

[Lloydthumper]

Any of you other guys in here that have threaded pipe as I have chime in. They could have had everything right and not threaded the pipe far enough for the dies. The taper on the end of the pipe comes from the end of the die. If they stopped to short the end of the pipe would not have alot of taper and it would not thread in very far at all. It will still work the taper just runs out quickly as oposed to one that is threaded back farther. Do what makes you feel best about the deal. If you don't feel comfortable with it don't use it.

 

[ws6formula]

Here are some pics of the factory cut threads and the Home Depot (HD) cut threads. Some of the HD cut & threaded pipe ends do appear to have some taper, though not as much as factory threads. Other HD threads have almost zero taper. I have already installed some of the worst HD cuts that had pretty well zero thread taper. I plan to leak test these zero/minimal taper threads in next few days. Note, most of my HD pipe was cut and threaded by one rep, though I did get some pipe cut and threaded by another HD rep on a prior visit. I likely had about 15 cuts/threads done by HD with most being on one day.

 

[slddnmatt]

i would say the die is probably out of adjustment and, the operator is supposed to run the pipe through the die until 2 threads are visible then slap it open, there should be a very visible taper if not... its wrong. i did a lot of pre-fab and changing teath in my dumb days....

 

[nissan_crawler]

that looks like poo. It would be unacceptable to me. i have an ancient hand threader that does WAY better than that junk.

 

[Palmetto]

Thread Makeup for NPT fittings is:

1/2" NPT = 1/2"
3/4" NPT = 9/16"
1" NPT = 11/16"

That doesnt look like a tapered thread to me. I would make sure you get atleast you Min. thread engagement with a good pipe dope. If you have to, mark it with a sharpee, or a piece of tape to get your bearings.

 

[dipper]

I guess this is why I'm running copper for my airlines, much easier to work with.

 

[Mr_fixit]

They look like ****, either something is wrong with the tool or the operator of the tool. I'd take them back..

 

[Aceman]

I'd take them back. Using them with 1.5 threads engaged even using pipe dope is hackish. Show that guy those pipes, the one with proper taper and the one he cut with straight threads. Make sure his dies are NPT like stated above. There's no reason to have straight threaded dies in a Home Depot machine. I am an electrician by trade, when we thread conduit even we use NPT dies.

 

[fireguy]

Retrun to home cheapo with your bad threads. Grab a factory ****** off the shelf. Show the HD plumber how a factory ****** threads into the pipe threading machine die, showing the amount of threads sticking out of the die. then show him his work. His work will not seal w/o using excessive pressure. As a plumber, he should know this already. He may also need to adjust the dies. I have been told hand tighten and then wrench tighten 6 turns per fitting. Pipe dope is not a sealer, it is a pipe lube.

I use a hand threader for 80% of my work. The balance is done with the 700 threader or the hand groover.

 

[danski0224]

They use the automatic stop Ridgid die heads. The operator can adjust the depth of cut by sliding the sizing ring above or below the indicated pipe size hash mark. The cut is stopped automatically when the pipe end pushes the die head release lever, and there is no adjustment for the stop point.

That is part of your problem- the employee is lining up the indicator with the 1/2" mark on the die head. The hash mark probably needs to be about 1/32 or a little further below the 1/2" pipe size indicator.

Another part is the quality of the pipe thread dies in the die head.

HD has a maintenance team that changes the dies based on time (or if someone breaks one). OEM Ridgid dies are expensive- and the HSS dies even moreso. Home Depot (at least one store I am familiar with) tried aftermarket dies a little while ago- those **** big time. The OE Ridgid HSS dies are now back in that machine.

The final part is the quality of the pipe.

HD buys made in China pipe.

It is garbage.

The pipe OD is a little big, the pipe is full of rust and the metal is soft.

Even with new dies in the threader, newly cut threads look bad with chunks of the thread just torn off of the pipe (just like your picture) Slowing the threading machine down does help, but the problem does not go away entirely.

Adjusting the die head for a deeper cut will usually tear all of the threads from freshly threaded **** HD China pipe. You gotta set it right the first time.

The plumber at your store does not know how to use that Ridgid threading machine.

 

[geaugafletcher]

No small wonder this plumber had to take a "day job" to make ends meet. A guy that can't see anything wrong with mixing up straight and tapered threads shouldn't be allowed to operate a microwave, let alone plumb somebody's house.

 

[arthur1920]

how about the pre threaded sections of pipe at HD? I was thinking of assembling my air pipe entirely from the pre threaded selections.

 

[swgray]

There should be 11 threads cut onto the pipe. The ones pictured that were threaded for you only have 9-10 threads. Thats why they seem tight from the start.

 

[GSSFC]

Thx for replies - I told the HD rep that was cutting and threading the 1/2" black pipe that I was using it for air. I was also buying a number of NPT fittings (ie. couplers, elbows, etc) at the same time. The HD rep told me he was a plumber.

If he is a plumber, why is he threading pipe at HD? There certainly aren't a shortage of plumbers in my area. My guess is the guy who helps load the lumber is a framing contractor, and the guy cutting the wire is a master electrician....I love it!

Tim

 

[ws6formula]

Thx for all the feedback. Just an update...
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I did try and use some of Home Depot (HD) cut and threaded pipe. I originally installed some of the HD cut and threaded pipe a few weeks ago and finally got around to testing it yesterday. I think I would not have tried installing some of the HD pipe if I had read all the feedback first.
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As I said before, I could only hand tighten the HD connections 1 to 1.5 turns (a few even less than that). I used Masters Pro Pipe dope for all connections. I made sure all connections were tight. I pressurized the pipe with air. All of the factory threaded and cut pipe connections have no air leaks. Many of the HD cut/threaded pipe connections have leaks. If I pressurize the pipe at 90 PSI..within 2hrs or so...the pipe will lose all pressure. I sprayed soapy water on the HD connections and I can see air bubbles at many HD connections.
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So, it looks like I will be taking off the HD pipe. It looks like this HD cut and threaded pipe will not seal properly. I learned a little about pipe and and pipe cutting/threading and how important it is to make sure your pipe is threaded and cut properly and has the proper taper. I assumed the HD rep knew what he was doing and never really thought I could get pipe cut and threaded so poorly. I wish I had known this when I went into HD to get the pipe. Now, I know to check the pipe and thread and thread taper etc. if anyone is going to HD or Lowes (or other hardware stores) to get their pipe cut and threaded they should check all cuts and threads.
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I am not sure if I should take the pipe back to HD and ask to get it recut and rethreaded or am I better off just going to a local plumbing supply company and having them cut and thread some pipe. Either way, I will now know a little about checking the quality of the cuts and threads , taper etc.

 

[JohnK007]

Hey, I learned alot about pipe and pipe threading reading this thread too. Thanks !!

 

[Uncle Buck]

Thx for all the feedback. Just an update...
.
I did try and use some of Home Depot (HD) cut and threaded pipe. I originally installed some of the HD cut and threaded pipe a few weeks ago and finally got around to testing it yesterday. I think I would not have tried installing some of the HD pipe if I had read all the feedback first.
.
As I said before, I could only hand tighten the HD connections 1 to 1.5 turns (a few even less than that). I used Masters Pro Pipe dope for all connections. I made sure all connections were tight. I pressurized the pipe with air. All of the factory threaded and cut pipe connections have no air leaks. Many of the HD cut/threaded pipe connections have leaks. If I pressurize the pipe at 90 PSI..within 2hrs or so...the pipe will lose all pressure. I sprayed soapy water on the HD connections and I can see air bubbles at many HD connections.
.
So, it looks like I will be taking off the HD pipe. It looks like this HD cut and threaded pipe will not seal properly. I learned a little about pipe and and pipe cutting/threading and how important it is to make sure your pipe is threaded and cut properly and has the proper taper. I assumed the HD rep knew what he was doing and never really thought I could get pipe cut and threaded so poorly. I wish I had known this when I went into HD to get the pipe. Now, I know to check the pipe and thread and thread taper etc. if anyone is going to HD or Lowes (or other hardware stores) to get their pipe cut and threaded they should check all cuts and threads.
.
I am not sure if I should take the pipe back to HD and ask to get it recut and rethreaded or am I better off just going to a local plumbing supply company and having them cut and thread some pipe. Either way, I will now know a little about checking the quality of the cuts and threads , taper etc.

Take it back to HD and get it re-cut, they will gladly do it. I used to work in the plumbing dept in the HD in my town. Speaking from experience I can tell you that it is real easy to grab a die that is out of adjustment and not notice that you are cutting a **** thread with no taper until you have done several. HD has their thread dies set so that normally the employee is not supposed to have to adjust anything other than select the correct die, kick the machine on then just watch it cut till the automatic release opens the die at a preset length. That works great and can even lull a guy that has done tons of threading into a false sense of trusting that no one has screwed with the die sets and assume all is as it is supposed to be. They idiot proof the process as much as they can, but every so often some ******* comes along and screws with the dies.

As I said, I have hand threaded, and machine threaded miles of pipe on older Rigid machines in a plumbing shop years ago and never had any issues other than HD machine on one occasion. I hate to admit it happened during a very hectic day and I did not even notice the **** threads till the guy brought the bunch of pipe back to me in a bit. After apologizing to the guy and feeling like an idiot I cut him some decent threads. Just trying to cover too many customers at one time is all it boiled down to. I have seen that happen several times, but only the one time to me. Go get them recut.

 

[ws6formula]

Update: I did take the pipe back to HD. The same guy was there. He ran the pipe through and rethreaded all fittings. He said the dies were the correct NPT (tapered) 1/2". He said the dies were recently replaced and were ok. The threading/cutting machine was a Rigid 535. He had to adjust the threading size slightly below 1/2" on the Rigid 535 indicator. When he left the threading indicator at 1/2" it did not cut the threads deep enough. Basically, he kept on moving the indicator a touch at a time and then rethreaded the pipe. After each rethreading we spun a 1/2" female coupling onto the pipe to see how many turns the coupling would spin on by hand. We tried to get the coupling to spin on by hand about 3 to 3.5 turns by hand (wish I would have checked that the first time I had the pipe threaded). I am going to assemble the pipe in the next few days and hopefully will have no leaks.

 

[WhatsNext?]

Thanks very much to all at this thread for your comments !

They saved me a LOT of trouble in my computer stand project.
http://www.garagejournal.com/forum/showthread.php?p=905787#post905787

Knowing what I learned here, I checked the thread situation on my visit to Home Depot.

It turned out there were a number of prefab factory threaded pipe segments, which did not properly match threads with the other standard joint fittings.


I ended up having the very nice fellow at Home Depot rethread those factory threadings, so everything actually worked.

His threadings of other odd sized lengths of pipe, threaded onsite there, worked properly as well.

Thanks again !
I wouldn't have known to check it otherwise . .

 

[Tom2]

Looks better than the pipe I had threaded by Do It Best hardware. Some of the threads were missing alltogether.. Talk about operator error.

Doped it up, installed it. Zero leaks.

In hind site, I probably should have had him redo it..

With just an air line, I wouldn't get too concerned over it.

 

[nickleone]

British standard pipe threads are the same pitch as US NPT. But there is no taper on the threads. They usea a sealant. It works for them. But they are British.
"US and Britain separated by a common language" Chutchill

Nick

 

[Sterff]

From just looking at the picture you can tell he didn't ream the pipe and remove any burrs from the end. He probably didn't use the right die set or it wasn't set to cut the threads correctly.

 

[TheGrooveking]

I suspect they ordered replacement cutters for their threading head and ended up putting in NPS not NPT. The pictures you posted show straight threads with no taper, which would indicate that even if they set them to cut deeper the threads will still be straight.

TheGrooveking

 

[Torque1st]

I have taps and dies I use to touch up threads if needed. It is often needed with the cheap import pipe and fittings. The time it takes to futz around with the import **** makes the price of US made stuff much more attractive. Finding US made stuff is a problem tho.

 

[mad57]

Exactly why i returned all my pipe from hd and just bought copper much easier , worked out great for me. hd has junk!!!

 

[gorilla]

Home Depot needs to change the inserts in the threading die. The torn metal and poor finish on the threads indicates that they are dull.

 

[toomnyprjts]

thanks everyone for the info. glad i looked before i leaped. putting in new floors and have to raise 1 radiator to accommodate new floor height. hoping to get this done by this monday.
does anyone know if Lowes does any better job cutting and threading pipe?
thanks in advance for the quick replies.