Gray water tank pipe leak

[tiinytina]

Sent: 5/7/2006

hi all,
    another successful Allegro journey, and this time after a couple hours of putzing on her we finally just relaxed in the sun, under our now patched awning... but...
    Noticed water dripping from the pipe that carries the gray water to the release valve, directly in the dead center of the RV. Looks like the PO let her freeze as the leak is not due to road debris but is well under about 1.5" of sprayed on foam insulation. The Gray water tank on our allegro is on the opposite side from the black water tank and the release valve, so this piece of pipe spans the width of the trailer and is "jury-rigged" up in 2 places by plastic pipe tape hung from somewhere under the chassis (covered in that sprayed on foam stuff). It just drips under normal operation but when I dump the tanks it really flows from the leak.
   Pipe looks to be 1.5". I guess I have 2 options but don't know which would be better. 1 is to replace the pipe from the valve backwards to the tank which involves 2 90 turns. The other is to cut out the offensive section, about 18" of sodden foamed pipe, sand off the foam and put in couplers...
   Is this pipe PVC? Can I just use Sched80 and be done or is this stuff specialized. My valves all work, and tanks are fine.. I'm assuming... (bum-U-ME) that the joints are glued into place and the only points of removal are at the tank junction and the valve.... other than access via a sawzall or hacksaw that is... found all sorts of water tank repair info in my search but no pipe info...
Thanks!
Tina

[OldEdBrady]

Sent: 5/7/2006

On the Whiny Beggar, from the tanks to the release valves is just ordinary sewer pipe.  I'm not sure what size, but that's all it is. 

And, yes' it's glued with whatever it is they use for ordinary sewer pipe.

[brians1969]

Sent: 5/9/2006

campers use the black ABS pipe, not the white PVC pipe. Available at most building centers and some of the bigger hardware stores.
brian

[tiinytina]

Sent: 5/9/2006

thanks!
I have both a Home Despot and a Low's... (pardon the puns) on my way home. Still at a loss as to whether it would just be a good idea to replace the whole piece or just excise this section.  Guess I should also buy some of that spray insulation stuff to put around it as protection since it sits in the middle in back of the tires....
tina

[tiinytina]

Sent: 5/16/2006

Evenin' all,
   OK just discussin' with the hubby (he's the contractor I'm the plumbers daughter)... about replacing the pipe this coming weekend as She is going campin' the first weekend of June and don't want the embarrassment of a "leaky teeky" . So... bowing to you knowledgeable ones.... Should we just replace the entire piece from the tank ( 3 90's + 8') or cut out the offending section (18")? In the long haul (pun intended) would it be best to just use sched 80 pvc? or the abs? price really isn't a consideration as I'd rather do it right the first time than do it again... (my dad talking there).
  As one consideration this thing was installed prior to spraying the undercarriage with foamy cra* so everything but the flange into the tank and the outlet valves are covered in an inch of dried foam...
  I bow to the Winnie cahoonas!   (I am not worthy I am not worthy... hee hee)
cheers
Tina

[Lefty]

Sent: 5/17/2006

Tina,
There is a slight size difference between sewer line (black) and fresh water lines (white), that is done on purpose to keep plumbers from accidentally crossing a line during a building project (Eeeewww!!)
For this reason, you will need to stay with the regular black lines. It's cheaper too.

I would replace the entire run, instead of trying to piece it together & risk a leak.
Be very careful of where the line is joined at the tank. After all these years, it will surely be brittle!! Cut through the line with a hacksaw diagonally across the joint just enough to cut through the pipe, without harming the stub. Then use pliers to carefully pry open the cut to loosen the pipe BEFORE trying to pull it away. You may have to make several such relief cuts, if the pipe is well glued.

[tiinytina]

Sent: 5/19/2006

The leak looks to be due from freezing by one of the PO's. The only reason I would go up to sched 80 from the ABS would be for wall thickness. The pipe runs about 2' in back of the tires so I figured the sched 80 wouldn't get dinged as much as thinner material. The old stuff is caked with hardened spray foam. I think I will go for replacing the run from the valve across to the first 90 at least. We'll see. may try cutting out the offensive area first then seeing if I can clean off enough of the insulation to make a clean joint. If not the whole thing goes.... The price be between abs and sched 80 for so little pipe is negligible at this point.
Thanks everyone!
Tina

[salplmb]

Sent: 5/19/2006

the pipe and fittings for pvc and abs are not interchangeable. the cements used to glue them together are different. there is a glue that will bond both together but in my experience it dose not last well. these rigs move a lot more than a house dose. the pvc pipe is a solid core pipe and the abs is a sort of foam core. pvc can take a lot more abuse and is more ridged and more expensive. the abs is lighter and less expensive. they also make what is called a no hub coupling. you can connect any pipe to another with this band. be sure to use the proper sanitary fittings and not just your reg. pvc fittings. abs fittings are for plumbing only. sch 80 pipe is usually used for elec. or sometimes water mains. there are no sch. 80 sanitary fittings. sanitary fittings have a longer radius turn so as to let the water run through them smoother. also they are designed to flow the water through the tee so as to not make turbulence that disrupts the flow through the fitting. I'm sure this is more than you wanted to know.
sal

[DaveVA78Chieftain]

Sent: 5/19/2006

Sal,

While septic system design may not be the most pleasant of subjects, it is a gravity drain system therefore your points should be taken into account when repairing or designing a holding tank system.   That no hub coupling is used in many installations to connect the polyethylene holding tank stub pipe to the black abs pipe.   The cement issue is also important.  Then the possibility of the pipe types not being interchangeable could bring about big headaches (connection leaks).  Best to stay with what has become the industry standard so that if you later have to replace slide valves or repair damage things will work out easier.   Just changing from the old off-size Thetford drain connector (where you connect the flex hose up) to the current standard is well worth it on my rig.  I now can purchase flex hose attachments without worry or trying to locate that odd adapter.  I view this as thinking ahead to make life easier rather than more complicated.

Dave

[tiinytina]

Sent: 5/19/2006

thanks guys,
   So I think I will try to first go buy some ABS and 2 joiners.... then just try cutting out the offending section, and replacing it...  if that doesn't work I'll work on replacing everything from the valve back to the first 90 with abs.  Since this is only the grey water lines "Sweeping 90's" aren't the utmost importance. The current ones look to be standard PVC type 90's.  The only reason I was considering switching over to PVC is simply the proximity of this  pipe to the dual back tires. I didn't plan on spraying new insulating foamy stuff on it either or should I?

tina

[tiinytina]

Sent: 5/21/2006

OMG! wow... a repair that actually took as much time as I allotted... that won't happen again in this century I'm sure....

I hacksawed out 13.5" of sodden insulation covered pipe. bought 2 ABS rubber 1.5" couplings ($7.50 each at very local True Value), searched dads garage for a scrap of pvc as couldn't buy anything under 8'... and voila... done. Total time about 1 hour, including driving "Gone" to neighbors asphalt driveway and back to its parking place.

I did however find out that the coach batteries are dead.. as the genny just went click click click....  oiy vie. They are Deep Cycles... so hook them up to the trickle charger and cross fingers....

Tina