What would be the best plasic to make some custom irrigation fittings?

[6061billet]

I'm working on a drip irrigation system for the garden and I've reached the point that it might be easier to machine some NPT threaded fittings rather than cobble together various fittings from one of the big box stores. It's an outside application that will be fed from a rain barrel with a pump so I'm not worried about failure. I have some acetal rod on hand but I was thinking nylon rod might work better.

[chipmaker4130]

ABS machines nicely and holds up pretty good in the sun.

[garyhlucas]

I machine custom PVC pipe fittings all the time. Type 1 pvc comes in rods of all sizes up to 10" or more. Nylon, delrin etc. work but must be black in color or the sun deteriorates them badly.

[Black_Moons]

I machine custom PVC pipe fittings all the time. Type 1 pvc comes in rods of all sizes up to 10" or more. Nylon, delrin etc. work but must be black in color or the sun deteriorates them badly.

Not 100% sure if its just 'black' that makes them stable.
IIRC, the UV stabilizers are one of the bigger costs in plastic. But I think 'carbon black' actually makes a good UV stabilizer (or at least, UV blocker) and is reasonably cheap, so most black plastics will be much more UV stable then white plastic. You CAN get light colored plastics that are UV stable but you likely can expect to pay more then for UV stable black plastics.. You likely can also find black plastics that are not UV stable.

You may very well fine that UV stability is the biggest issue for durability of the part designed for outdoor use in the sun, because even the strongest plastics become exceptionally brittle when exposed to a lot of UV, if they don't have a lot of UV stabilizers.

Try to buy from somewhere that has some kind of datasheet for the materials and look for UV stability, or noted for 'outdoor applications' in the plastic you buy.

[1-800miner]

How about aluminum? Say...6061billet?

[JRouche]

ABS machines nicely and holds up pretty good in the sun.

+1 on this. I have also. It machines a lil nicer than white PVC, seems less gummy, and it holds up well. Before using white PVC I usually like to go with the grey electrical stuff. Very durable.. JR

[Mike Burch]

Nylons absorb moisture, and swell when wet.
Black alkathene is widely used for irrigation fittings and pipe. It lasts forever.

[OwenG]

+1 what Mike said!

[Lee in Texas]

If it's being used in a plumbing application and and has NPT threads, why wouldn't a PVC nipple work? If you don't need threads on both ends, cut the nipple and glue into a fitting. If you want cut threads instead of cast threads, you may need to go to a plumbing supply store, rather than a big box store.

[CarlByrns]

If it's being used in a plumbing application and and has NPT threads, why wouldn't a PVC nipple work? If you don't need threads on both ends, cut the nipple and glue into a fitting. If you want cut threads instead of cast threads, you may need to go to a plumbing supply store, rather than a big box store.

Yep- a TOE (Threaded One End) nipple. Plastic nipples are glueable and sized to fit socket fittings.

[Carm]

Just random thoughts.
Try to avoid threads if you can, especially female, and particularly in PVC. Barbs are easy and hose bands are cheap, if necessary on low pressure.
If you use PVC try to use Carlon (the grey electrical stuff) to get the UV resistance. It does well in freezing weather.
All the PVCs/ABS can be glued in combination w/universal glue.


1-800miner, I see what you did there.

[CCWKen]

White PVC gets chalky and brittle down here in the South Texas Sun. While it holds up to pressure, I wouldn't use it if it's exposed and there's any chance of flexing such as moving the drip lines, etc. I ran stand pipes up 4x4s with hose bibs about every 150' when I put in the well line (Over 750'). That's been about 18 years ago now. I broke one of bibs off the pipe pulling on a hose two summers ago. I went through all of them and replaced the bibs with screw-mount type ball valves after that. The pipe was clamped to the posts but the clamps went over insulation that weathered away. I now just wrap the post and all for the occasional winter freeze. (Maybe once or twice a year.)

[lakeside53]

Much as I understand the desire are you sure you really want to make these? I have 1500 feet of drip/soak system.. I buy my fitting etc from"mrdrip" and others online. Dirt cheap and very good.

oh.. PVC.. the gray stuff. I've had some outside for years.. no problems.. so mine must have UV inhibitors.