I’ve got a problem with either UV degradation or environmental degradation of PVC pipe serving my drip irrigation system on the pecan grove. The well head and manifold is under a shelter, but there is about a 30 foot run of 2″ schedule 40 PVC that is exposed to the elements.
The glue and pipe seem to be degrading quickly, developing leaks at fittings. It’s a complex system, from the well pump to the centrifugal sand separator, then to the filter, then splitting to two different solenoids.
My question is, can I paint the pipe and fittings to resist UV, and if so, what sort of paint ? Or should I wrap it with shade cloth or the ubiquitous duct tape ? With all of the mechanicals, it can’t be buried. I know one of you must have run into this before with a more traditional water supply.
Thanks. Greg.
Replies
I would recommend valve boxes for all the valves and other mechanical parts, and burying the rest of it. Besides protecting the pipe from UV, it will reduce damage to the mechanical bits, and make it possible to drive equipment through the area, if that's a consideration. Even if you don't want to go to the trouble of digging a trench and installing valve boxes, I think dumping a couple inches of dirt on top of 30 feet of pipe would be a lot easier than any of the alternatives you've brought up.
Of the three possibilities you mentioned, I think duct tape would be the easiest and the most effective. A quick Google search suggests that there might be brands of duct tape that are specifically rated for exterior use.
You might use gray pvc conduit when it becomes bad enough to replace. It is schedule 40 and I believe you can get gray glue for it too. It is uv protected and I have never seen it degrade. You can get it at HD or Lowes or your local electric supply.
I have found that a simple coat of cheap latex paint prevents deterioration from sunlight. As an electrician we use a grey PVC conduit that it resistant but not impervious to UV. Given enough of the Florida sun even this stuff can fail. In most areas there is little mechanical abuse this is not much of a problem. The degraded conduit never gets enough abuse to cause any damage
Where there is likely to be hard contact, industrial sites and warehouses even when protected by bollards, a UV degraded conduit could easily be broken and leave the wires exposed to damage. In these cases I have tried painting the pipes with latex paint. This seems to have greatly slowed the degradation due to sunlight exposure. I used a cheap industrial grey latex, it was handy, and slopped it on fairly thick. Every conduit I have used it on has maintained, as well as I can tell, the full strength of the PVC even when smaller conduits next to them have blanched and become brittle.
I used to do lots of solar systems in a prior life and can tell you that PVC, exposed to the sun, can and will become brittle. I can also tell you (based on my experience with trying to insulate hot water pipes for domestic hot water solar systems) that duct tape or the black tape used to wrap gas pipes will quickly degrade when exposed to sunlight.
I second the recommendation to cover the valves so that they can be protected yet be worked on, and to bury the pipe that doesn't contain maintainance items.
John