What is everyone's opinions on pvc vs ductile iron for water mains? I've been thinking here lately as a lot of local systems are seeing a huge amount of breaks. Is pvc as prone to breaks as ductile? Which one last longer? Are the breaks worse on pvc or ductile? Are the breaks the came type, dose pvc get radial breaks just like pvc? Or are they lateral breaks? If it is a lateral break will it run the full stick length? Dose pvc develop blow holes as often? Sorry for the lengthy question. I'm just curious to hear others experiences/thoughts.
Moving this to General Industry. Depends on the installation IMO.
Can you elaborate on install cm1995?
I've yet to fix a water main break. I do like the fact that you can encounter a ductile pipe with an excavator and not break it. PVC is not as tough to that kind of damage. Both are gasketed installs with some flexibility. Ductile can have a more aggressive field lock gasket.
I also like the fact ductile bells will accept a large amount of deflection where as pvc will not.
I'm a big fan of all DIP and fittings but like the price and weight of C900 pipe better. Most of the leaks we fix on plastic are older IPS PVC, usually cracks inside 90's or around tee branches.
I worked for a company that did ductile mains with case backhoes. All single axle dump trucks, and we had a trailer that we would drop by the supply house and they would load 10 tons of fittings on it, and the pipe would get drop shipped from the plant. Yes those fittings added up!
Well installation wasn't the best choice of words, environment it will be used in is a better term. Soil conditions being first and foremost. DIP - Good for rock and rocky trench installations. Urban and certain industrial applications where there are multiple utilities and the likely hood of digging around it is high. However DIP can deteriorate in acidic soils if the cement coating is compromised. Certain chemicals can also eat DIP up rather quickly. I saw the video of a 6" DIP lateral less than 1 year old where the bottom of the pipe was completely gone - you could see the #57 stone bedding. That lateral was for a recently built Taco Bell...take what you will out of that. C900 PVC is lighter but more fragile than ductile however it can withstand acidic soils and chemicals better than DIP. A country water main stretching a couple of miles in sandy or clay soils is a perfect use of C900. Lighter and cheaper to purchase and install. So more bang for a local water dept's budget. On the flip side the city I live in just replaced about 2 miles of a 30 year old 8 and 12" PVC main that was installed in rock and apparently not bedded properly. Our house was serviced by this line and it constantly leaked. It was replaced with ductile. Just my $.02. Both have their place.
Where I live, some water mains are shallow, and they use iron so they can unthaw it with electricity. Public works has equipment just for that. I notice even new installs using iron. Never questioned the choice between the blue bruit or the iron. All water mains are bedded and back filled with gravel, and all sanitary are bedded with stone. I used to think it had something to do with the 2 former communities on either side of the river, but both sides have been engineered for either iron or plastic.
Why do they freeze it?
As I get older, I wish it didn't get cold enough to freeze
So people can have ice tea on a hot afternoon!
Sure, but "unthaw" = freeze
Finally, an interesting topic. Lol. Here in this part of Ontario PVC is the most widely used pipe material for distribution watermains. I only run into DIP at railway crossings or as risers in a fire system for an ICI building. Transmission mains are CPP or concrete encased welded steel. The PVC is easier to work with and has the same service life or better than DIP. HDPE pipe is starting to show up more and more these days. Directional bore guys love using it.
Not enough cover over it and or flow through it in the winter time and it freezes.
As a guy who makes his living performing hydrostatic pressure and leakage tests on watermains, I assure you that neither DIP or PVC joints can be deflected enough to be useful without leaking ( at test pressures).
the available deflection is quite useful when following undulating terrain.
I believe he was being facetious, considering the name IceHole. But yes, a lot of the older mains in the city are shallow.
I'm a big fan of HDPE. Stronger than PVC, welded joints, and cheaper than PVC. Johnson County, KS requires any sewer lateral run of more than 80' be welded SDR 17 HDPE. Their code department has a lot bad ideas, but I can't argue with that one.
Does it come in straight sticks? That would be my only issue is getting it to lay flat because HDPE curves.
Low pressure sewer systems are catching steam here for new residential developments. 3-4" HDPE main with 2" laterals. Each house has their own sump and sewage pump that pumps into the main. Drastically lower sewer installs upfront however the downside is pump maintenance over the years. Probably knocks $8-10K off the cost of a new 80' lot.