PDA

View Full Version : Tweaked main line repair...


PurpHaze
10-17-2007, 11:05 PM
Leak on 4" main line at bell connection under concrete. Same site we've already made three repairs under concrete and still have another to go. (It's under a driveway used for food/other deliveries so plan is to keep spur off and make repairs during winter holidays.)

Line was so tweaked that when I made the first cut it snapped 5" out of alignment vertically and several inches horizontally where it dives under a fire access lane. No way to use Dresser couplings because the amount of deflection was so great that I didn't want to chance it. All joints have been solvent weld so far so decided to just do the old 90/90 routine to get everything to line up again. Pressure loss from the 90s not important because spur only feeds smaller zones in front of school (was supposed to be looped main but never happened).

We ended up having to open more concrete than originally expected because our Bobcat operator snagged/cracked some when making the original dig but it was no big deal and ended up being necessary in the end. The additional dig allowed us to straighten out the pipe on one end and to cut back both sides beyond actual bends in the pipe. As always... bigger is better when it comes to working with bigger pipe.

Told the boss that I wouldn't be surprised if we end up having to repair every joint on the system main leading to the front before it's all said and done.

PurpHaze
10-17-2007, 11:08 PM
Last of the pics for today. We'll turn the spur back on tomorrow, check repairs and then turn it back off until December. Off to newfound interest of GeoCaching. :)

CAPT Stream Rotar
10-18-2007, 07:01 AM
purp-as par the course thats an awsome reapir..I cant belive the pipe moved that much after you cut it...would you call that a "stressed pvc joint"? The 4 90's look great..neat as part the course....
::takes notes::

what size is that pipe?

FIMCO-MEISTER
10-18-2007, 07:23 AM
Purp on 4 elbow repairs, which we do many of due to ground shift and roots, I'm curious to your install technique. The one problem with 4 ells that always bugs me is my inability to do a one third turn on the last glue. Also at some point two joints are going to have to be glued and pushed on at the same time unless you have lots of play. If that is Leo between you and me he is heading for a massive heart attack.

PurpHaze
10-18-2007, 09:16 AM
I cant belive the pipe moved that much after you cut it...would you call that a "stressed pvc joint"? The 4 90's look great..neat as part the course....

what size is that pipe?

It's 4" SCH 40 pipe and, yes... I'd say it was under a lot of stress both laterally and horizontally.

PurpHaze
10-18-2007, 09:28 AM
Purp on 4 elbow repairs, which we do many of due to ground shift and roots, I'm curious to your install technique.

I glue the stubs onto the first 90s then glue them onto the main line ends using a level to get them somewhat on the same geometrical plane so the last horseshoe part goes on easier.

The one problem with 4 ells that always bugs me is my inability to do a one third turn on the last glue.

This is where confidence in your glue comes in. We use a good glue and plenty of it on both the pipe and inside of the fitting so we are positive we have good coverage. I'd rather be messy with extra glue than not have enough.

Also at some point two joints are going to have to be glued and pushed on at the same time unless you have lots of play.

We ran a string line between the stubs and eyeballed the best angles closest to right angles, marked our cuts with a marker and then just trusted that we'd done our homework. We had a small bit of play in each pipe so this also helped line them up better for the final horseshoe piece. We then cut the cross-pipe and dry fit it between the stubs to make sure we're neither too short or too long. We then glued the 90s onto the long piece and used level concrete to make sure the 90s were true to each other. Lots of glue slides them right on without binding and then we press and hold with a shovel or breaker bar to make sure they don't pop off.

If that is Leo between you and me he is heading for a massive heart attack.

He is a big boy and has been trying to lose weight. Rides a bike to work every day but just can't seem to shed much. Course... he loves his beer too. :)

Wet_Boots
10-18-2007, 09:53 AM
I always wonder about beer-lovers who ride bikes. Do they still have their driver's licenses?

WalkGood
10-18-2007, 10:04 AM
Pressure loss from the 90s not important because spur only feeds smaller zones in front of school (was supposed to be looped main but never happened).



If any pressure loss WAS important, what would you do differently?

Would using 45*'s help in any way?

Wet_Boots
10-18-2007, 10:15 AM
twenty-seven unions :)

Mike Leary
10-18-2007, 01:12 PM
twenty-seven unions :)

:laugh: :laugh: Nice repair Purp, all of our worst nightmares when you cut
into the line & it goes "twang!". :cry:

PurpHaze
10-18-2007, 10:34 PM
If any pressure loss WAS important, what would you do differently?

Would using 45*'s help in any way?

Not really a whole lot I could of done given the circumstances that everything is under concrete which precluded ripping out too much of it and going back far enough on both sides to realign the pipe. The use of 45s would decrease the fitting pressure loss by about half as much "100' of pipe equilevent" versus 90s but using them in these situations is extremely hard (in my experience). Very hard to get them all lined up properly yet still get them fully seated in the fitting without putting additional stress on any of the joints. Two is bad enough and then dealing with four 4" ones would be a real mess.

One althernative might be to use mechanical joint fittings such as long barreled couplings that would hold at the deflection point yet possibly tweak the pipe again subjecting it to stress and failure down the line. Wouldn't be a good choice under concrete.

I'd probably still go with the 90s and hope like hell that the original designer used the buffer method of designing that would take into account small changes in the future. :)