Tac Weld the 2" LB's closed

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220/221

Senior Member
Location
AZ
That may be the sign of a poor joint. Solvent welding should fuse the two surfaces.

Nope, I am accurate on this one. LOTS of experience......TONS of experience.


Question. If you use PVC conduit and metal LB's, wouldn't you have to somehow ground the LB's? Seems like it.
 

iwire

Moderator
Staff member
Location
Massachusetts
220/221 said:
Nope, I am accurate on this one. LOTS of experience......TONS of experience.

Can't agree with you here and neither do the people that make the cement ......... but hey What do they know? :wink:

Pipe and fittings are bonded together by means of chemical fusion. Solvents contained in primer and cement soften and dissolve the surfaces to be joined. Once the pipe and fitting are assembled, a chemical weld occurs. This weld strengthens over time as the solvents evaporate.

http://www.ppfahome.org/cements/index.html

I suspect you have not taken apart correctly made joints.
 

220/221

Senior Member
Location
AZ
Don't believe everything you read.

Maybe it is just interpetation of "chemical weld".

When I think "weld" I think that the two surfaces are welded and bonded together to become one. That is simply not the case.

I can take any joint apart and show you. I can't count the times that I have done this.....probably a hundred. Were they ALL bad joints?


You don't have to believe me but I am right :)

I started off in the trades in 1970 working with PVC and have installed miles of the stuff. I learned quickly that a good joint had to be a tight fit. If the pipe was slightly undersized, you could put as much cement as you want on it and it still wouldn't hold.

Years later, in 1980, I met an engineer who explained how PVC joints were so strong and it all made sense. It's all about the tolerance.

Like I said, I have done miles of PVC, both plumbing and electrical and I have done a LOT of rework and repair. I gaurantee that I can take any PVC coupling apart and still leave a clean surface to reuse it. No grinding involved because the pipe/fittings do not fuse together like a metal weld.

If you are bored some day, give it a try. Find a piece of 2" that has been glued and set for however long. Use a sawsall to carefully slice thru the outer part (coupling or belled end). To make it REAL easy, do the same thing on the other side. Use a flat screwdriver and your linemans to chisel under the fitting/bell and it will pop off easily in maybe two or three pieces. No (or very little) fusing has taken place.

The PVC cement basically fills that small gap and creates the tight fit. Haven't you ever had undersized pipe before and no matter how long you let it sit, it will still pull apart? I have.....hundreds of times. It's especially troublesome when it's going into a light pole base :mad: NOT something you want to come apart.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
The fact that it has to be a tight fit does not change the fact that it is a solvent weld. PVC cement is not designed to fill a gap, it is only designed to weld the two surfaces together and it can't do that when there is not a tight fit between the parts to be welded. If fusing is not taking place, the was an issue with the amount of solvent, the cleaning of the pipe, the age of the solvent, the tightness of the fit or the installation methods.
 

iwire

Moderator
Staff member
Location
Massachusetts
220/221 said:
Don't believe everything you read.

I don't.

But one mans story from the trenches does not make me change my view.

And one mans view above the people that make the product ... well...it is what it is. Just an opinion.

Maybe it is just interpetation of "chemical weld".

That certainly could be.

I can take any joint apart and show you. I can't count the times that I have done this.....probably a hundred. Were they ALL bad joints?

I have my doubts that would be the case once we tested that theory,


You don't have to believe me but I am right :)

At least as far as you care to find out. :smile:

I started off in the trades in 1970 working with PVC and have installed miles of the stuff. I learned quickly that a good joint had to be a tight fit. If the pipe was slightly undersized, you could put as much cement as you want on it and it still wouldn't hold.

I agree, it has to be tight, we are not adding material like a traditional weld so if the fit is loose it will never stick.

If it was epoxy, or traditional 'glue' it would stick even with a loose fit.

Years later, in 1980, I met an engineer who explained how PVC joints were so strong and it all made sense. It's all about the tolerance.

We still agree, it has to be tight to work.
 

220/221

Senior Member
Location
AZ
If fusing is not taking place, the was an issue with the amount of solvent, the cleaning of the pipe, the age of the solvent, the tightness of the fit or the installation methods.

Heh heh...you are wrong too.


Glue a piece of PVC together, send it to me and I'll take the joint apart leaving a clean smooth surface on the pipe with no sanding or grinding. It's a fact. The only fusion going on is at a microscopic level. Is it "welded" microscopically? I suppose. I'm not a rocket scientist. All I know is that the pieces separate smoothly and cleanly with relative ease.

If it was fused like welded metal, there is no way it would come apart. I tell you I've done this a hundred times for various reasons and they were not all improper joints.

I can't believe you have never taken apart a PVC joint at some point in your careers.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
220/221 said:
I can't believe you have never taken apart a PVC joint at some point in your careers.
Many many times and never with the ease that you have found and never finding a clean smooth surface.
 

Buck Parrish

Senior Member
Location
NC & IN
Bentworker said:
roundheadtrigroove.gif





If the utility company will let you use tamper resistant screws you can get a 50 pack of 10-32's from mcmaster for about $15.00




This is a good suggestion. I'll try that.

The service is underground coming up to the gutter.
I will do it next week.

Mean while in an other juriiisdiction. I used two pvc LB's today above the meter up to the weather head.
I didn't think twice about it. If some one wanted to make a tap. They would go above the weather head any way.
My neutral is the same size as my hots. In an LB you can't tell which is which. (THHN)Can you imagine trying to tap off these on a live circuit. I guess it could be done.
Take a plastic drill stand on a fiberglass ladder. Drill a self tapper in to the wire with a one hole lug on it. I'm just trying to picture what the poco is thinking.
I'll let y'all know what happens.
 

TOOL_5150

Senior Member
Location
bay area, ca
220/221 said:
Don't believe everything you read.

Maybe it is just interpetation of "chemical weld".

When I think "weld" I think that the two surfaces are welded and bonded together to become one. That is simply not the case.

I can take any joint apart and show you. I can't count the times that I have done this.....probably a hundred. Were they ALL bad joints?


You don't have to believe me but I am right :)

I started off in the trades in 1970 working with PVC and have installed miles of the stuff. I learned quickly that a good joint had to be a tight fit. If the pipe was slightly undersized, you could put as much cement as you want on it and it still wouldn't hold.

Years later, in 1980, I met an engineer who explained how PVC joints were so strong and it all made sense. It's all about the tolerance.

Like I said, I have done miles of PVC, both plumbing and electrical and I have done a LOT of rework and repair. I gaurantee that I can take any PVC coupling apart and still leave a clean surface to reuse it. No grinding involved because the pipe/fittings do not fuse together like a metal weld.

If you are bored some day, give it a try. Find a piece of 2" that has been glued and set for however long. Use a sawsall to carefully slice thru the outer part (coupling or belled end). To make it REAL easy, do the same thing on the other side. Use a flat screwdriver and your linemans to chisel under the fitting/bell and it will pop off easily in maybe two or three pieces. No (or very little) fusing has taken place.

The PVC cement basically fills that small gap and creates the tight fit. Haven't you ever had undersized pipe before and no matter how long you let it sit, it will still pull apart? I have.....hundreds of times. It's especially troublesome when it's going into a light pole base :mad: NOT something you want to come apart.



I am going to agree [specifically] with 220/221 that a good solvent weld CAN be sucessfully taken apart without little to no damage to the bell. I have done it before. However, I have read that the purple primer and then 'glue' actually melt the 2 pieces of PVC to create a weld. Now, I also agree with that in the fact that if you take the purple primer and brush it on PVC, and let it sit, you can actually scratch some of the actual PVC pipe away with your fingernail.

~Matt
 

Buck Parrish

Senior Member
Location
NC & IN
TOOL_5150 said:
I am going to agree [specifically] with 220/221 that a good solvent weld CAN be sucessfully taken apart without little to no damage to the bell. I have done it before. However, I have read that the purple primer and then 'glue' actually melt the 2 pieces of PVC to create a weld. Now, I also agree with that in the fact that if you take the purple primer and brush it on PVC, and let it sit, you can actually scratch some of the actual PVC pipe away with your fingernail.

~Matt


Yes, I agree. Speaking of that I saw a ten ft section of electrical pvc tied in to a 2" plumbing drain under a house today.
I thought to myself. If Pierre we're under here with me. I would get him to take a picture of it.
 

iwire

Moderator
Staff member
Location
Massachusetts
Question.

Has anyone successfully 'glued' any non-PVC material together with PVC solvent cement?

Ever notice no matter how much spills on the can top you can still unscrew it?

Why is that?

Because it is not glue, it does not stick, it has no 'stick'

The only thing that makes it work is the chemical melting of the plastic.

I can take apart arc welds, does that mean they are not welds?


But I will try not to let facts get in the way of opinion. :grin:

Rock on. :grin:
 

TOOL_5150

Senior Member
Location
bay area, ca
iwire said:
Question.

Has anyone successfully 'glued' any non-PVC material together with PVC solvent cement?

Ever notice no matter how much spills on the can top you can still unscrew it?

Why is that?

Because it is not glue, it does not stick, it has no 'stick'

The only thing that makes it work is the chemical melting of the plastic.

I can take apart arc welds, does that mean they are not welds?


But I will try not to let facts get in the way of opinion. :grin:

Rock on. :grin:


As far as welding the 2 pieces together - I agree, thats what PVC cement does.

Now as far is it not having any 'stick' - You must have never spilled any of it on your arm... It sure sticks to hair pretty good. OUCH! :grin:

~Matt
 

iwire

Moderator
Staff member
Location
Massachusetts
TOOL_5150 said:
Now as far is it not having any 'stick' - You must have never spilled any of it on your arm... It sure sticks to hair pretty good. OUCH! :grin:

LOL :grin:

You got me there, it does have plenty of stick with hair, I think it melts the hair to some extent.

It is also good at finding the small cuts that otherwise would have gone unnoticed.
 

TOOL_5150

Senior Member
Location
bay area, ca
iwire said:
LOL :grin:

You got me there, it does have plenty of stick with hair, I think it melts the hair to some extent.

It is also good at finding the small cuts that otherwise would have gone unnoticed.


Oh yeah - forgot about its magical ability to find small cuts that you would otherwise never notice, and man, does it let you know when it finds them.

~Matt
 

Minuteman

Senior Member
Originally Posted by Bentworker

If the utility company will let you use tamper resistant screws you can get a 50 pack of 10-32's from mcmaster for about $15.00


My opinion, though not worth much.

The LB's are being installed by an electrician even though they are on PoCo's side. As an electrician you must install according to the listing. The LB is not listed to be drilled and locked, welded, or glued shut.

I'm just saying. :)
 

iwire

Moderator
Staff member
Location
Massachusetts
Minuteman said:
My opinion, though not worth much.

The LB's are being installed by an electrician even though they are on PoCo's side. As an electrician you must install according to the listing. The LB is not listed to be drilled and locked, welded, or glued shut.

First it absloutly makes no diffrence that an electrian is intalling it. The NEC does not even use the word electrian. What maters to the NEC is the service point and who controls the installtion.

I'm just saying.

And I am just saying that it is not listed to not do those things. :)

Do you have some listing and labeling info that says I can not drill an LB?

But lets say the electrical inspector says no, you can't seal the LBs. Fine, the power company still does not have to hook up your service till you figure something out with the LBs. You would end up removing the LBs and using 90s.

It's no different then the power company putting a lock on a CT cabinet, meter socket or trough.
 

Minuteman

Senior Member
iwire said:
It's no different then the power company putting a lock on a CT cabinet, meter socket or trough.
I hear ya. I just think this is one of those times when the mechanic gets caught in the middle and has to appease both the PoCo and the AHJ , with little or no input.
 
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