Conduit threading in classified areas

Status
Not open for further replies.
tkb said:
If properly threaded, this wouldn't be an issue.
Click to expand...

If properly threaded one would not be able to thread a coupling all the way on one piece and then back it up to couple to another piece, which is the whole point of using running threads at a coupling (even though it is not allowed).

Lets also not forget this thread is about hazardous locations. If I was to see running thread at a coupling I would rather see it in a non classified location than a classified location. Once the threading die is all the way on the pipe there is no more taper to the threads so any fittings installed are not going to match up very tight without the taper to the threads.
 
kwired said:
If properly threaded one would not be able to thread a coupling all the way on one piece and then back it up to couple to another piece, which is the whole point of using running threads at a coupling (even though it is not allowed).
Click to expand...
I wouldn't call being able to thread a coupling all the way onto a conduit properly threaded.

kwired said:
Lets also not forget this thread is about hazardous locations. If I was to see running thread at a coupling I would rather see it in a non classified location than a classified location. Once the threading die is all the way on the pipe there is no more taper to the threads so any fittings installed are not going to match up very tight without the taper to the threads.
Click to expand...
If using an NPT die as you should, and threading a conduit to the end of the die, the threads on the conduit will be tapered. Not straight threads as you imply.
 
tkb said:
kwired said:
tkb said:
If properly threaded, this wouldn't be an issue.
Click to expand...
If properly threaded one would not be able to thread a coupling all the way on one piece and then back it up to couple to another piece, which is the whole point of using running threads at a coupling (even though it is not allowed).
Click to expand...
I wouldn't call being able to thread a coupling all the way onto a conduit properly threaded.


kwired said:
Lets also not forget this thread is about hazardous locations. If I was to see running thread at a coupling I would rather see it in a non classified location than a classified location. Once the threading die is all the way on the pipe there is no more taper to the threads so any fittings installed are not going to match up very tight without the taper to the threads.
Click to expand...
If using an NPT die as you should, and threading a conduit to the end of the die, the threads on the conduit will be tapered. Not straight threads as you imply.
Click to expand...
As I said earlier, a moot issue... but to do it "properly", the running threads should be NPSM. The standard coupling has NPSM threads.
 
Last edited:
tkb said:
I wouldn't call being able to thread a coupling all the way onto a conduit properly threaded.

It is not, that is why running threads are not allowed as described.


If using an NPT die as you should, and threading a conduit to the end of the die, the threads on the conduit will be tapered. Not straight threads as you imply.
Click to expand...

I think you misunderstood. The die is tapered, but once it is fully on the pipe anything behind the die is not tapered, it is same as tail end of the die. The only tapered part of a so called 'running thread' is the part where the die was at the time the threading was stopped.
 
kwired said:
I think you misunderstood. The die is tapered, but once it is fully on the pipe anything behind the die is not tapered, it is same as tail end of the die. The only tapered part of a so called 'running thread' is the part where the die was at the time the threading was stopped.
Click to expand...
True.

However, most dies on threading machines have an easily adjustable cut depth. The trailing threads could easily be made to snug-in-coupling size.

I'd say part of the reason for running thread being a violation is that not all threading equipment have provisions for making a well crafted joint, or jobsites lacking NPSM dies and the willingness and/or knowledge to use properly... in addition to a substatial number of exposed threads after installation.
 
Smart $ said:
...I'd say part of the reason for running thread being a violation is that not all threading equipment have provisions for making a well crafted joint, or jobsites lacking NPSM dies and the willingness and/or knowledge to use properly... in addition to a substatial number of exposed threads after installation.
Click to expand...
The main reason the use of running threads at a coupling is a code violation is because there is large reduction of conduit structural strength at the point of the exposed theads after you have run the coupling on to the other section of conduit.
 
kwired said:
I think you misunderstood. The die is tapered, but once it is fully on the pipe anything behind the die is not tapered, it is same as tail end of the die. The only tapered part of a so called 'running thread' is the part where the die was at the time the threading was stopped.
Click to expand...

Yes, I agree. I must have misread. :slaphead:
 
Smart $ said:
True.

However, most dies on threading machines have an easily adjustable cut depth. The trailing threads could easily be made to snug-in-coupling size.

I'd say part of the reason for running thread being a violation is that not all threading equipment have provisions for making a well crafted joint, or jobsites lacking NPSM dies and the willingness and/or knowledge to use properly... in addition to a substatial number of exposed threads after installation.
Click to expand...

Some of us only have hand threaders that are non adjustable. If I have a big enough job I do have a light industrial customer that lets me use a power unit - still have to use my hand threaders with it - just don't have to use as much elbow grease.

If I ever buy a really nice threader I will probably never get much chance to use it - hopefully if that is the case I have enough helpers they are the ones that will be using it.
 
K8MHZ said:
I didn't say anything about useful. How could it be useful in a coupling, the only instance mentioned?

Where would a running thread be useful at all? Remember, the paralell part of the thread will be small in diameter and makes for a sloppy fit.

I have seen guys try to use them for close nipples because they didn't know how to make them with tapered threads.
Click to expand...

I guess I'm one of those guys. How would you make a close nipple tapered?
 
buddhakii said:
I guess I'm one of those guys. How would you make a close nipple tapered?
Click to expand...

Close nipples are tapered. Try threading a locknut on one. If the nut eventually stops, it is because of the taper. If you had a close nipple with non tapered thread you would be able to start the locknut on one end and thread it all the way across the nipple and remove it from the other end. You could make such a nipple with non tapered thread by cutting so called "running threads" then cutting the threaded portion in a suitable length for close nipple.


The machines that do cut real tapered close nipples as well as other short length nipples grip the pipe on the inside - that is how they can make these without messing up the threads on the opposite end. If you look inside of a short nipple you can usually see the bite marks from the threading machine.
 
I know all of this. My question is how do you make a close nipple in the field with tapered threads? K8 stated that he has seen guys making close nipples with running threads because they didn't know how to make tapered ones which tels me he knows how to make them in the field.
 
buddhakii said:
I know all of this. My question is how do you make a close nipple in the field with tapered threads? K8 stated that he has seen guys making close nipples with running threads because they didn't know how to make tapered ones which tels me he knows how to make them in the field.
Click to expand...
To make a close nipple in the field, start with two sections of pipe already threaded on at least one end. Couple them together. Cut one next to the coupling at close nipple length and thread. Advise doing so very cautiously using powered equipment.

Tip: Cutting threads longer on the section not being used for the close nipple allows it to go into the coupling further and butt up to the close nipple section. This will prevent the close nipple section from expanding the coupling and threading into the coupling too deep to cut the threads.
 
Last edited:
Smart $ said:
To make a close nipple in the field, start with two sections of pipe already threaded on at least one end. Couple them together. Cut one next to the coupling at close nipple length and thread. Advise doing so very cautiously using powered equipment.

Tip: Cutting threads longer on the section not being used for the close nipple allows it to go into the coupling further and butt up to the close nipple section. This will prevent the close nipple section from expanding the coupling and threading into the coupling too deep to cut the threads.
Click to expand...

Good idea - you could even cut a coupling so it is short enough both nipples thread in far enough to hit each other.

You have to use a threading that has adjustable dies for different pipe sizes. Typical hand threading dies will not let you thread this as the coupling will not fit into the head that holds the dies.
 
kwired said:
Good idea - you could even cut a coupling so it is short enough both nipples thread in far enough to hit each other.

You have to use a threading that has adjustable dies for different pipe sizes. Typical hand threading dies will not let you thread this as the coupling will not fit into the head that holds the dies.
Click to expand...

I don't use couplings. For some reason they like to jam to the conduit and it sucks trying to get them off.

I make a piece with 8 to 10 inches of running thread on one side of about a foot long stick of pipe. Then, I flip the pipe around and clamp the running threads into the threader. Next, I thread the pipe so that only about 1/8 to 1/4 of an inch is left not threaded.

Now all that is left is to cut the pipe (on both ends if necessary) so that only the tapered part (about 3/4 of an inch) is left on each side.

Caveat: If you don't use a coupling it's real easy to squish the pipe in the threader if you are trying to clamp onto running threads. A sharp die and lots of oil really helps matters. Oh, and pay attention if you are using the threader to cut pipe where it has been threaded. The cutter likes to follow the threads and if you aren't quick.....let's just suffice it to say it's better to cut the pipe with a saw. :ashamed:

The last one I did was in a steel mill where we were 20 minutes from our supply con box in the dead of winter. I was showing my foreman how to do it with an old nasty Rigid threader with dull dies. It took three tries, but I finally got one cut. It took me about a half hour as I did not lose my temper. So that was 1/2 hr J-man pay plus 1/2 hour foreman pay and a stick of pipe.

What's that, about $120 (total package, union scale) for a close nipple? :D

Not really avoidable since it would have been a 40 minute round trip PLUS rooting through the con box for a close nipple (that may not have even been there).
 
Last edited:
Smart $ said:
To make a close nipple in the field, start with two sections of pipe already threaded on at least one end. Couple them together. Cut one next to the coupling at close nipple length and thread. Advise doing so very cautiously using powered equipment.

Tip: Cutting threads longer on the section not being used for the close nipple allows it to go into the coupling further and butt up to the close nipple section. This will prevent the close nipple section from expanding the coupling and threading into the coupling too deep to cut the threads.
Click to expand...

OR... you could use the proper tools like a Ridgid 300 and a 819 Nipple Chuck.
http://www.ridgid.com/Tools/Nipple-Chuck-Kit/EN/index.htm

300_Complete_3C.jpg
819_Nipple_Chuck_Kit_3C.jpg
 
Status
Not open for further replies.
Top