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View Full Version : Anatomy of a main line leak?


PurpHaze
10-02-2007, 02:50 PM
The guys repaired a 4" main line leak under a concrete sidewalk while I was gone and Leo saved the "leak" for me which occurred at a SCH 40 glued bell joint. Since I had the time I cut the bell open to investigate the leak and here's some pictures of what I found.

I've glued a new 4" fitting together (didn't have an extra bell and bevelled end so just glued together a coupling) and will tear it apart sometime next week to compare to this one. I'm not sure if it was glue failure or what. Any ideas?

Kiril
10-02-2007, 03:34 PM
I would guess slightly deformed pipe. The gray cement might have prevented that leak since it has better gap filling properties than the blue.

Mike Leary
10-02-2007, 03:37 PM
Maybe LACK of glue? Did you find any? I see just primer & not too much
of that either. You feeling better?:weightlifter:

Kiril
10-02-2007, 03:42 PM
Maybe LACK of glue? Did you find any? I see just primer & not too much of that either.

Good point. Don't see much glue in that area and a big spot lacking primer.

jerryrwm
10-02-2007, 03:43 PM
Yeah...looks like what little cement used was pushed ahead by the pipe. Easy pop out of the pipe also indicated lack of cement.

WalkGood
10-02-2007, 03:48 PM
The guys repaired a 4" main line leak under a concrete sidewalk while I was gone and Leo saved the "leak" for me which occurred at a SCH 40 glued bell joint. Since I had the time I cut the bell open to investigate the leak and here's some pictures of what I found.

I've glued a new 4" fitting together (didn't have an extra bell and bevelled end so just glued together a coupling) and will tear it apart sometime next week to compare to this one. I'm not sure if it was glue failure or what. Any ideas?

Maybe cleaning and prep was not done well enough. The pic of the glued surface appears that either the glue did not adhere (poor prep), glue not spread properly, or joint not twisted when freshly connected with the glue.

I've heard a plumber state that after thorough cleaning/priming n prep, glue smeared in well and evenly coat all mating surfaces , he hasn't had a leak if some glue squishes out when connected (but not puddling out all over). Also use a 1/4 turn motion when assembling.

If the glue was jelly-like consistency it may not adhere well, and should be tossed out.

Kiril
10-02-2007, 03:49 PM
Yeah...looks like what little cement used was pushed ahead by the pipe. Easy pop out of the pipe also indicated lack of cement.


Would be nice to know how they applied the glue. To the pipe, fitting, or both. Perhaps if we could see a section of the pipe you cut out?

Mike Leary
10-02-2007, 03:58 PM
I'm thinking poor primer application (should have been multiple coats)
and being glued-up at:drinkup:30 :laugh:

CAPT Stream Rotar
10-02-2007, 04:01 PM
dam 4 inch pvc is huge....

Mike Leary
10-02-2007, 05:55 PM
dam 4 inch pvc is huge....

Out of the mouths of babes.:laugh:

FIMCO-MEISTER
10-02-2007, 06:09 PM
LACK of glue Did you find any? I see just primer & not too much
of that either.

I have examined all answers closely and after review of the pic decided this is the one I consider most correct.

Of course I edited it slightly to make it seem really correct.

Mike Leary
10-02-2007, 06:23 PM
I have examined all answers closely and after review of the pic decided this is the one I consider most correct.

Of course I edited it slightly to make it seem really correct.

Oh oh, I see another personality developing here.."Professor-Meister".

Bigred350
10-02-2007, 07:06 PM
Isnt blue glue a medium bodied glue?

On a 4" pipe I would have used the strongest glue on the market.

PurpHaze
10-02-2007, 09:09 PM
Maybe LACK of glue? Did you find any? I see just primer & not too much
of that either. You feeling better?:weightlifter:

The only real glue found was at the very ends. Other than that, each section was easy to pop out.

PurpHaze
10-02-2007, 09:10 PM
Yeah...looks like what little cement used was pushed ahead by the pipe. Easy pop out of the pipe also indicated lack of cement.

Kinda along the lines I was thinking. I do know that the contractor on this site was fired and brought back twice.

PurpHaze
10-02-2007, 09:15 PM
Would be nice to know how they applied the glue. To the pipe, fitting, or both. Perhaps if we could see a section of the pipe you cut out?

Here's a couple of the pipe pieces I popped out.

irrig8r
10-02-2007, 09:39 PM
There's a lot of dirt mixed in with that glue. Contaminated glue or dirty pipe?

londonrain
10-02-2007, 09:39 PM
I repair more leaks when blue glue has been used. When using blue glue I have noticed that the glue would rather say on the dabber than transfer to the pipe and fitting unless the can is brand new. Get the least bit of water on the dabber and the transfer ratio is even worse.

PurpHaze
10-02-2007, 09:40 PM
dam 4 inch pvc is huge....

Handling 3" and 4" for us is like handling 3/4" and 1" for others since we deal with so much of it including 3" lateral lines. You just get used to it and it's really not much different. Just takes a little longer to cut/glue and you need bigger trenches so you don't put any binding pressure on the joints. I'm sure anyone could adjust to it in short order as we've had many of our grounds guys who've had only contact with smaller pipe cutting, glueing and setting fixtures in short order when working with us.

Out of the mouths of babes.

LOL... Especially when he's used to poly. I'm sure he could make the transition and with his gumption I'd bet he'd be butt fusion welding large PE in no time flat.

PurpHaze
10-02-2007, 09:46 PM
There's a lot of dirt mixed in with that glue. Contaminated glue or dirty pipe?

Your guess is as good as mine. Without being there when the joint was glued it's all guess work anyways. In other leaks/breaks I have a pretty good idea what happened but this one is a "best guess" scenario for me.

The main line leak to the north was where a tee had pushed off and the leak to the south they had the 90 in a bind and not much of a thrust block poured. It'll be interesting to see what is up with the next two leaks since they're between all the ones already repaired.

And then... this is the same contractor that used saddle clamps on many of the field zones' valves instead of glueing in a tee.

PurpHaze
10-02-2007, 09:52 PM
I repair more leaks when blue glue has been used. When using blue glue I have noticed that the glue would rather say on the dabber than transfer to the pipe and fitting unless the can is brand new. Get the least bit of water on the dabber and the transfer ratio is even worse.

Until these three sites with all their problems we've experienced many more gray glue leaks than with blue glue. However, not all glue of a particular color is created equal. We spec out Plumb Tite and have had great success with it even on the 8" pipe we have on a couple of sites. However, not being there and inspecting what they're doing/using at the time of installation is a whole 'nother story.

We always make sure there is plenty of primer on both ends, ring glue around the pipe end, ring it inside the fitting, re-ring glue on the pipe end, insert and twist like it should be to spread the glue and hold for 30 seconds to make sure it doesn't want to back out.

londonrain
10-02-2007, 09:56 PM
Here is a pic of a 3" that I pulled apart with my hand.....

PurpHaze
10-02-2007, 10:05 PM
Here is a pic of a 3" that I pulled apart with my hand.....

At least you have some glue mixed in with the primer. When I popped out the pipe on the 4" it's very smooth except where the rusty appearing area is.

The more I think about it there were gaps on the bevelled end of the pipe not filled in with glue. An article I read (looking for a copy) on glue joints stated that the welding takes place mostly on the end of the pipe and innermost part of the fitting. I'm kinda leaning towards the suspicion that they just didn't put enough glue on when making the weld. I know that when I glued my test pieces together I got a healthy bead on both the inside and outside as is common. Guess I'll have to wait until I tear my test pieces apart but I want them to set up for awhile (but I'm not about to wait three years). :)

FIMCO-MEISTER
10-03-2007, 06:01 AM
At least you have some glue mixed in with the primer. When I popped out the pipe on the 4" it's very smooth except where the rusty appearing area is.

The more I think about it there were gaps on the bevelled end of the pipe not filled in with glue. An article I read (looking for a copy) on glue joints stated that the welding takes place mostly on the end of the pipe and innermost part of the fitting. I'm kinda leaning towards the suspicion that they just didn't put enough glue on when making the weld. I know that when I glued my test pieces together I got a healthy bead on both the inside and outside as is common. Guess I'll have to wait until I tear my test pieces apart but I want them to set up for awhile (but I'm not about to wait three years). :)

I think this is correct. When I bought my first van from an old irrigator named get this "Rainey Westberry" he told me to use those large copper tube style cutters on all my mainline. Said that I needed a perfect straight edge to my pipe because the seal occurs where the pipe meets the stop piece inside the fitting. Bells don't have stop pieces so I guess you are depending on more total pipe being glued in. I'm not so anal about it now but I do focus on very straight hacksaw cuts. If my hacksaw cut is slightly angled I'll recut it. Doesn't happen very often I must say. Same with my kwik-cuts.

FIMCO-MEISTER
10-03-2007, 06:07 AM
LR is right about the blue glue. We are as guilty as some but it gets used sometimes way beyond its best viscosity point. I've many times tilted the can and scraped the side looking for some good glue to get a job done when I didn't have a can of back up glue. Dinky pipe is a little more forgiving on this no no.

PurpHaze
10-03-2007, 08:23 AM
We'll toss (or set aside for non-critical situations) glue that gets clumpy or very dirty. When we work on mains or main line repairs we always have fresh cans because the larger sizes require more glue and we want it to be as virgin as possible. I'd rather make good glue joints than having to come back in and repair something again.

Another thought occurred to me on this glueing problem. On rare occasions a cut will not be perfect (i.e. not good enough for a normal transition... usually from too long a cut) or will back out. If the whole process isn't started all over (re-primer and re-glue the joint) then there may not be enough glue if the parts are just pushed together again.

We also adhere to the initial set/cure times as established by our glue manufacturer before undue handling of the pipe/joint... just to be on the safe side.

Kiril
10-03-2007, 08:59 AM
Here's a couple of the pipe pieces I popped out.

That first pic looks like too much glue in the fitting, not enough on the pipe.

Perhaps they also let the primer dry too much before fitting the pieces together?

On dinky pipe systems I don't put glue in the fitting unless I'm making an in ground repair. On pipe that size, both the fitting and pipe need copious amounts of glue. I go with 1/3 bead on fitting, 2/3 on the pipe.

I agree with your glue regiment. Critical and constant pressure pipe fitting gets a new can, or at least one that is fresh. The non-critical pipes get the cans that have been laying around for a while but haven't gelled up yet.
:)

irrig8r
10-03-2007, 11:09 AM
My understanding has always been that it doesn't matter if the primer is dry or wet when you glue....in other words, it's purpose is to clean and soften the surface, and once it's done that it doesn't matter. In fact, if it's too wet with primer, the glue gets thinned a little, no?

Meanwhile, my supplier reminded me yesterday about how low VOC cement doesn't apply as easily as the old stuff used to. and it seems to me that I make more swipes around with a dauber these days before I'm satisfied with an even application. Funny what we get used to doing without thinking about it..

BTW, I almost always use IPS Weld-On, either 2711 or 2721.

One more thing... I seem to remember someone telling me not to apply glue to both ends when using a bell end... but I do anyway. Maybe this contractor heard the same info I was given and didn't apply to both...

PurpHaze
10-03-2007, 04:53 PM
Decided to cut into my glue experiment and check out the bonding on one small section. Pictures are pretty self-explanatory. I'm going to let the rest continue to cure and then I'll check other pieces at later dates. The major thing I can't duplicate would be the stresses and shock that the pipe fitting is subjected to as if it were a part of an actual main line.

Mike Leary
10-03-2007, 05:01 PM
Great shots Hayes..I agree with all of you..except the Scotsman from Dallas.
Hacksaws will deposit shavings that will foul valves, not to mention our
beloved brass nozzles...get the good red handled pvc clippers.

FIMCO-MEISTER
10-03-2007, 05:35 PM
Great shots Hayes..I agree with all of you..except the Scotsman from Dallas.
Hacksaws will deposit shavings that will foul valves, not to mention our
beloved brass nozzles...get the good red handled pvc clippers.

Purty hard to do service work without my folding Lenox hacksaw. RainMaster blows out the crumbs. Has it happened ? yeah. Has it happened often enough to make me worry about it? no

Mike Leary
10-03-2007, 05:39 PM
Purty hard to do service work without my folding Lenox hacksaw. RainMaster blows out the crumbs. Has it happened ? yeah. Has it happened often enough to make me worry about it? no

Then (& I agree about tite situations), I'd buy a Makita battery recip saw
w/ the # 72 (I think) metal cutting blade...me & Hank have them, less
shavings means fewer callbacks.:)