I placed some decorative fountains in my south-facing front yard and have run a 1/2" Schedule 40 PVC irrigation pipe that runs underground to the back of each fountain so that I can install an automatic refill valve. The pipe comes up through the ground, through the concrete platform and from there is exposed to the harsh desert elements. It can get up to 122 degrees in the summer. It's been 115 so far this year.
I've been looking online for some type of sleeve to protect the white PVC that comes up from the ground. I need about a foot or so for each of my two fountains. The elbows have gotten slightly "toasty" looking and are now sort of amberish in color due to burning in the sun. For the time being I've wrapped and tied some torn white blanket bits to protect the pipes from further damage but it looks tragically ghetto at this point. Since these pipes will be pressurized at all times I want to do all that I can do prevent failure which could be awful (e.g coming home to a geyser shooting 20ft into the air and wasting tons of water for who knows how long).
I don't mind if I have to replace something every year or so as the sun and heat destroy everything out here.
Since it's only a foot or so, you could transition the PVC to brass, copper, or stainless steel before it emerges from underground. The metal pipe will be impervious to heat and sunlight. If you like the look of white pipe, just paint the metal pipe with a suitable white paint.