PVC – in the sun – getting brittle?
toolbear
| Posted in Construction Techniques on
Folks,
I have some planter boxes that are watered from PVC 40 runs attached to the existing irrigation system. Pulled the nipples and replaced with a run to each box. Stuff is painted.
Went to repair one and my PVC shears are not cutting it, they are cracking it. I commence worrying.
This stuff get brittle in the open?
Am I in trouble?
What to run in lieu of P-40?
The ToolBear
“Never met a man who couldn’t teach me something.” Anon.
Replies
Yep, the white stuff gets brittle in the sun. The grey electrical stuff is supposedly better.
In general, with plastics, white/clear is most UV-sensitive, and darker colors are less so (since the pigments help block UV).
Is "P-40" the same as "schedule 40"?
Matt
Yep, Sked 40 PVC in white. The ToolBear
"Never met a man who couldn't teach me something." Anon.
paint the P-40...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Did paint it. Lovely forest green - and brittle below.The ToolBear
"Never met a man who couldn't teach me something." Anon.
"What to run in lieu of P-40?" Black polypropylene is about the best choice for outside, direct exposure and is what most irrigation systems are run in (if they're done right).
iv been installing irrigation for 10 yrs. the black polyethelene expands/contracts heavily in dirrect sun. this needs to be compinsated for during planning. crosslinked poly vinyl chloride is 100% uv resistant but cost 10 times pvc. black poly also looks like c^&*. black poly is now availible in blue. Paint the PVC. but 1 yr in sun and the dammage is already done.
PVC starts as a powder. It wants to return to powder. What makes PVC plastic, both as a material and a physical property, are plasticisers. Essentially specialty oils. Some not too different from sex hormones. A concern for kids chewing on toys.
UV light and ozone can damage it and speed this process. Anything that is added or put on to retard or shield from these forces will slow the deterioration. A coat of paint can block the sunlight. Simple latex seems to adhere well and if put on thick enough slow the damaging effects of sunlight. Darker shades might be more effective but I have seen white work well.
Also, and independent of UV damage, over time these plastisizers leach out or evaporate. Is I understand it it is a matter of temperature, exposure to air and time. We sometimes get older PVC conduit that is stiffer, more brittle and less friendly to use a pipe shear on.
Electrical conduit and fittings typically has a UV blocking agent added to the mix to slow its deterioration. It also has more plastisizer added making it more flexible. Not uncommonly plumbing that needs to be torn out is easily taken out by striking the fittings with a hammer to shatter them. Electrical fittings will typically flatten before they crack.
In the end all plastic plumbing and conduits are becoming more brittle and weaker as time goes by. Nothing lasts forever. Galvanized steel is only good for 40 years or so. A lot of PVC plumbing has been around for 40 years and is still kicking. PEX, according to some, might last 100 years. A lot depends on when, where and how any material used is employed.
4LORN1,
That was a great post! Thanks. I now know why this crap is breaking...White PVC , What a lousy choice for rain gutters!
Interesting post. Sounds like entropy is happening a bit faster in my planter boxes.
Wonder about sweating up some copper for the above ground bits. That should be good for 50 yrs. What is that dark gray stuff with threads I see in the irrigation section? That work? These things are basically two lenghts of pipe, one valve and a 1/4 spray head.
We travel in the summer and rely on these things to water the plants. Don't want to be called because there is a geyser happening.The ToolBear
"Never met a man who couldn't teach me something." Anon.
i cannot tell what you are triing to water from where. the uv isnt such a big thing to me since anything exposed will likely be run over within 2 yrs. sched 80 seems to last longer the light must only be able to penetrate so deep. copper risers would look very nice but aluminum would be cheeper. you can sweat or thread or victulac or burr it and ram poly over it. I would never use sched 40 pvc for live mainline though.
NoWAY... PVC Fencing lasts forever... Why can't they make the water pipe from the same thing my fence is made of. It was twice the price of cedar and the company warrantys it for 50 years. Totally maintainenance free-that's what the salesman told me. It's only 6 months old and it cost me $50,000 US
How can all of you have axes to grind? Did your parents choke on a piece of vinyl or something?
This must just be propoganda against the vinyl/plastics industry... I don't believe any of you!
TIC ( I am absolutely-100% kidding-you believed it didn't you?)
L
GardenStructure.com~Build for the Art of it!
Question floating around is how are those PVC fences going to hold up long term. Some manufacturers seem to offer a lifetime warrantee. Given a sufficiently large fence going bad and the ready availability of crack addicts willing to kill people for an eightball it might be cause for worry. Enough at least to keep the back door locked.Of course in legaleeze lifetime sometimes translates into a set number of years. Of course the manufacturer likely runs this game from both ends. Defining down what 'life' and 'defect' and 'failure' are. How yellow does it have to get to qualify as 'yellowed'. One site I visited bragged that the company manufacturing the fencing and warrantee it has been in business for 100 years. Not sure it means much. Given the ease which companies can spin off, drop, portions of a corporation that proves troublesome.But who knows? Given the improvements in plastics technology and the UV inhibitors, evidently some manufacturers have made great gains in UV resistance by incorporating titanium dioxide in their mix. One brags of it making up 10% of their mix. Given the the reactivity of the material and resistance to UV it would be highly resistant to yellowing and might be, to some extent, self-cleaning. The dioxide catalyzing many organic soils and oils when exposed to UV into simpler compounds.I would think 20 to 30 years might be expected. Just a WAG. Perhaps twice that. Probably half of that from the 'also-ran' companies who will be riding the reputation of the best by providing a product half as good for 75% of the price. How does that stack up against a wood fence?
Wow 4... you have really researched it. I can show you a 7 year old pvc fence, nearly on the ground...I'll photograph later. Professionally installed. The pipes(used ni the 3 rail fence are shattering near the end and all are sagging. There's a couple on our composite decking page... scroll down to the bottom
http://www.gardenstructure.com/page/composite_decking.html
LGardenStructure.com~Build for the Art of it!
The use of uv inhibitors in vinyl products is an on going research effort by the vinyl industry. Unfortunately the laboratory for this research is at the consumer end of the pipe line.
The basic double carbon bond of the vinyl is the culprit. That c=c bond will breakdown with the right frequency of energy striking it. Unfortunately, that freg. is that of ultraviolet light. It acts as a kind of microwave for the bond, adding energy untill the bond weakens and seperates. Basic organic chemistry teaches this in the second semester, and I for the life of me , can't understand how the chemical industry can keep on denieing that simple fact.
They just keep reformulating with new and improved uv inhibitors, and shoving products out the door to be field tested for them by the consumer. A 30 year life is certinally better than the 10 year life of products 25 years ago, but it by no means as "final as vinyl" claims that they make.
Dave
i vote for a pressure rated abs
Thanks for the chemical insight. In theory adding enough, is 10% enough, titanium dioxide to the mix produces a situation where the outer surfaces of plastic might break down. further delayed by other UV inhibitors, but the filler protects all under it. Assuming the dioxide remains firmly attached they have a longer term solution.Same general way aluminum reacts with oxygen. The outer surface oxidizes, corrodes, but remains firmly attached protecting all under it.As you point out the field, largely at the expense of the consumed, is the ultimate testing laboratory. Given the climate extremes within the US I wonder if there might not emerge different plastic blends. Much like we have seasonal and regional changes to gasoline blends. Up in ND the frequent cold might demand a mix which won't shatter at sub-zero temperatures. Down here in Florida cold weather cracking is less an issue but the sun is significantly more powerful as there is a more direct approach angle for the UV rays through the protecting atmosphere. Every spring break we see Yankees who lay out for hours in northern climates get badly burned down here in a fraction of that time.Then again when those flying cars and fusion plants producing electricity at a cost too low to meter arrive, they said to expect them around 2000 so any day now, we might have low-cost durable ceramic or stainless steel fencing pretty soon.I can't wait for my flying car that runs on water. Going to be a blast to ride. Any day now I'm sure.
I got one!
But, ya gotta bring yer own tinfoil beanie.
SamT
The beanie?
I forgot the beanie!
Last flying car I had landed in the lake immediately after take off.
Shoulda remembered the beanie !
Dave