This isn’t really an emergency, but I’d like to take care of it next weekend, so I’m hoping I can gather some wisdom before then.
I have a sprinkler system under my lawn. I have taken out the grass and landscaped with low-water plants (I’m in southern California). I use the sprinkler pipes to feed a drip-irrigation system.
The problem is that the pipes are old, iron, and rusted. I had a PVC riser screwed into one of the sockets, but it didn’t fit well and the water pressure just forced it out.
I want to re-attach the riser but make sure that this time it will stay in place. I have a wire brush and will clean the threads. I will use a new riser with undamaged threads, and the guy at Home Depot suggested using some WD40 to make it easier to screw in. (Would teflon tape be better? I have some lying around.) I don’t want to use any rust removing compounds because I’m afraid they’ll melt the PVC/get into the water and poison my plants.
I was thinking that perhaps I should use Water Weld or this other epoxy I have around to make the riser stay in there for permanent. I used the other epoxy to seal a break in one of the iron pipes so I know it will stick and can handle the pressure.
Will it be okay to use one of these adhesives on both pipe and PVC? Should I just mold it around the junction of the pipe and riser, or should I go so far as to smear some on the threads of the riser? If I do that should I forego WD40/teflon tape?
Pre-made risers come in two kinds: rigid gray PVC, and a soft slightly flexible black ABS plastic. The latter are usually set up with multiple thread sets that you can cut off in 1/2-3/4" increments to be any length from about 8" down to about 2".
Clean the metal threads as best you can with the wire brush, steel wool, etc. Then thread the riser in carefully dry (i.e. with no lube or glue or Teflon tape).
If the threads feel tight & the riser is stiff in there, don’t muck it up with glue; leave it be.
If the threads are bunged up & the riser is floppy, the right thing is to replace the metal T or elbow. The crap DIY method is glue.
An intermediate idea is to try the other kind of riser; the extra stiffness or floppiness may make the difference you need. In fact you might look at using a metal riser as another alternative trying to get really bad threads to come together well enough to be water tight.
You know what the overall state of your system is. On my stuff I’m real reluctant to do the first jerry-rig redneck trailer trash craptacular repair on an otherwise properly assembled whatever-it-is. But if I already have 5 craptacular junkyard rednecks in there, I won’t mind too much doing a 6th.
Thanks LSL. I know the ABS ones you mean but I need more length–I need 18", because I need to accommodate a pressure reducer, debris trap, and connections to the 1/2" irrigation tubing, and the best way to do that in the spot it’s in is for the pipe to go up high, give it a 180 turn with fittings, and have the other gear parallel to the riser and pointing back toward the ground where it meets up with the tubing.
I thought about a metal pipe but the Home Depot guy told me they don’t make it any more–I should have he was wrong. This is the kind of thing I could use, right? Do you think that’s the best solution?
I did think I had the last PVC pipe threaded pretty tight, which is why I’m considering the epoxy. I really don’t want to do this again. As for the crappiness, I’m willing to tolerate it. The really good solution would be to run new PVC underground, but I’m not going to do that, which means I’m handcuffed to the old pipes because this riser is in the easement across the sidewalk. The rest of the landscaping I could run from a regular outdoor tap instead of the old sprinkler system, but there’s no way I can do that for the easement. I guess I could also break up a piece of sidewalk and have it re-poured to include a channel through which I could run the 1/2" tubing, but…not this year.
Yes that is a standard pipe length of 18". I would use that. Be sure that the female end it is fitting into has good threads & is not rusted too badly. Use the Teflon tape on it.
As far as replacing the pipe under the sidewalk, With a lot of digging, you can probably replace it with a new length of pipe without demolishing the side walk. What you would need to do is to find where it goes under the sidewalk. Dig two trenches on either side of the sidewalk. Dig down until you find the pipe on both sides. Cut it close to the sidewalk.
At this point, you can leave it in place & drill a hole for the new pipe in the dirt beside or under it. You can use a long wood bit & extensions to drill a hole slightly larger than the pipe. Drill from one side all the way through to the other side. When it is through, install the new pipe using a cap on the end of pipe that you will hammer on. The cap is used to protect the treads. You can now hammer the new pipe into your drilled hole. Be sure to get it all the way across the sidewalk. Then use couplers to attach it to your new lines. Steel pipe stands up to hammering better then the PVC does, but I have done this with both. If using PVC, make sure that the section that you are hammering on has extra length that you can cut off after the section is through the dirt. This will leave you clean, fresh ends that you can glue your fitting +/or couplers to.
It is a lot of work, but it can be done. I first did this about 40 years ago using a long bit with a brace. Hand power all the way. The sidewalk was four feet wide, but the hole I drilled ended up being almost eight feet long. The section of pipe I drove in was 16 feet long, as my grandpa wanted as few joints in the water line as possible. From start to finish took me about 18 hours. That was from clean lawn to clean lawn. These days, I hire the digging done, or I rent a track-hoe.
BTW, I now have a long drill bit used to place dynamite in mines that I use, no hammering for one inch diameter pipe and below. It just slides in.
