4 ms·

Cast iron :P Seriously, aside from requiring more skill to work with and not surviving well with large DC leakage currents (think: DC traction power from light

Cast iron :P Seriously, aside from requiring more skill to work with and not surviving well with large DC leakage currents (think: DC traction power from light rail), it's got a lot of advantages. Plastic piping in general is already disallowed in a lot of commercial construction. ABS is a valid alternative in some parts of the country, but is often already banned from being used in even residential construction in places where it gets very cold in the winter, as it shatters easily.

Ekaros 3y ago
I would say weight is an other drawback... At larger diameters segments get heavy and that brings own risks. Including things like stress injuries for workers.
- systems_glitch 3y ago
  Ugh, yeah, it can be a bear. Try dropping a 3-storey stack that's freeze fractured and ready to come apart on you :/
legitster 3y ago
> aside from requiring more skill to work with This is an understatement. This would essentially kill off plumbing as a DIY task and be a huge boon for professional plumbers.
- kevin_thibedeau 3y ago
  Copper is perfectly viable for interior small diameter pipe. Home owners aren't typically DIYing a cast iron main sewer.
  - mentalpiracy 3y ago
    Copper piping is unfortunately several orders of magnitude more susceptible to corrosion from a variety of sources: water acidity, high temperatures, and exposure to common household chemicals like bleach and drain cleaner.
    - amluto 3y ago
      Also CO2. Boiler condensate will eat copper pipe very quickly. And some well water and reverse-osmosis-filtered water is not so friendly to copper.
- systems_glitch 3y ago
  Remember that most cast iron isn't like it was for hundreds of years, nowadays there's no-hub and even if you do need to use hub and spigot, lots of folks use the neoprene bushing instead of oakum...and if you're still using oakum, you can usually use a modern sealant that comes in a caulk tube, instead of molten lead.
_8j50 3y ago
Why not aluminium?
- Turing_Machine 3y ago
  One reason might be that aluminum reacts with sodium hydroxide (lye), which is used in just about every drain cleaning product. "Yep, that 5" hole in the side of the pipe sure keeps everything flowing." Heh. The manufacturer could put a warning label on it, but you and I both know how well that's going to work in practice. Edit: oh, and the reaction produces large quantities of hydrogen gas, for extra fun.
  - thfuran 3y ago
    It reacts with acids and bases, so using the other half of drain cleaners that are sulfuric or hydrochloric acid won't help.
- poulsbohemian 3y ago
  I'm not a metallurgist, but it has been my observation that it deteriorates over time with hot / cold cycles. When I walk into a house built in the 1950s with aluminum pipe, I generally advise homeowners to expect to need to replace it within their time per ownership as my plumber friends have advised it has around a 75 year life at best.
Turing_Machine 3y ago
Classic cast iron drain pipe was connected with by pouring molten lead into the joints after packing them with oakum. Real medieval technology. I'm not super-fond of the so-called "no-hub" joints for cast iron. IMO, the rubber is just waiting to deteriorate underground and cause an expensive nightmare 20 years down the road.
- systems_glitch 3y ago
  The no-hub also won't carry the weight that hub and spigot cast iron will. I've seen a few roof drains come apart in business ceilings because the old cast iron was replaced with hub and spigot, and no one adjusted the spacing on the clevis hangers. First major rain, and there's too much weight for the no-hub couplings! You can of course run extra heavy no-hub couplers (four or more worm clamps per joint).
jakewins 3y ago
Did some DIY in the US (PEX and PVC), now live in nordics; water pipes here are copper (or PEX). Expensive, but basically just really tiny EMT conduit, so totally fine to DIY.
- dredmorbius 3y ago
  Guide for the perplexed: DIY: do-it-yourself (fairly widely known) PEX: Cross-linked polyethylene, a form of polyethylene with cross-links. Increasingly prevalent in plumbing applications. PCV: Polyvinyl chloride, a common plastic pipe, often white or black, may be rigid or flexible, widely used in plumbing for decades. "the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene)" per Wikipedia. EMT: Electrical metallic tubing.
  - dredmorbius 3y ago
    Erm, that should be PVC, rather than PCV.
amluto 3y ago
Is cast iron really so great for drainage? I get that it’s quiet and has nice mechanical properties, but acidic and/or oxidizing waste seems quite likely to eat it. So your bathroom sink, toilet and laundry are fine, but your kitchen sink? I would much rather use ABS in applications where it works.
- systems_glitch 3y ago
  The kitchen sink must not be too hard on it, after all it hits the main stack eventually :P I've seen a lot of NY state cast iron cast at the Monitor Iron Works, like Monitor and Merrimack, the US Civil War era ironclad warships. Still in service, still not leaking. Now of course that's survivor bias! You usually don't need expansion joints on cast iron...not that most residential construction gets them even when they are needed. It's detectable in an X-ray, unlike PVC, though I doubt that's of interest to 99% of DWV applications! No-hub is easier to adjust and rework than glued plastic pipe, as you can always loosen the coupling. Hub-and-spigot with rubber gaskets is effectively permanent, you have to seat it with lube and a mechanical assist puller usually. On the old lead and oakum joints, you can always dig out the lead to change orientation (not fun), or caulk it (as in with irons) more if there's seepage on a line.
  - amluto 3y ago
    My house had no shortage of cast iron DWV pipes leading from the kitchen that needed replacing. Fortunately they were accessible.
    - systems_glitch 3y ago
      All plumbing ought to be, it all fails. I still have a few more bits of galvanized screwpipe in our current house to replace, but what's left is closed up in walls :/
- systems_glitch 3y ago
  Cast iron is also not a problem at all to recycle -- it just gets to be woodstoves or brake rotors or more cast iron pipe or something. IMO that is one of its largest strengths as a sustainable building material.

Ekaros 3y ago

I would say weight is an other drawback... At larger diameters segments get heavy and that brings own risks. Including things like stress injuries for workers.

systems_glitch 3y ago
Ugh, yeah, it can be a bear. Try dropping a 3-storey stack that's freeze fractured and ready to come apart on you :/

legitster 3y ago

> aside from requiring more skill to work with This is an understatement. This would essentially kill off plumbing as a DIY task and be a huge boon for professional plumbers.

kevin_thibedeau 3y ago
Copper is perfectly viable for interior small diameter pipe. Home owners aren't typically DIYing a cast iron main sewer.
- mentalpiracy 3y ago
  Copper piping is unfortunately several orders of magnitude more susceptible to corrosion from a variety of sources: water acidity, high temperatures, and exposure to common household chemicals like bleach and drain cleaner.
  - amluto 3y ago
    Also CO2. Boiler condensate will eat copper pipe very quickly. And some well water and reverse-osmosis-filtered water is not so friendly to copper.
systems_glitch 3y ago
Remember that most cast iron isn't like it was for hundreds of years, nowadays there's no-hub and even if you do need to use hub and spigot, lots of folks use the neoprene bushing instead of oakum...and if you're still using oakum, you can usually use a modern sealant that comes in a caulk tube, instead of molten lead.

_8j50 3y ago

Why not aluminium?

Turing_Machine 3y ago
One reason might be that aluminum reacts with sodium hydroxide (lye), which is used in just about every drain cleaning product. "Yep, that 5" hole in the side of the pipe sure keeps everything flowing." Heh. The manufacturer could put a warning label on it, but you and I both know how well that's going to work in practice. Edit: oh, and the reaction produces large quantities of hydrogen gas, for extra fun.
- thfuran 3y ago
  It reacts with acids and bases, so using the other half of drain cleaners that are sulfuric or hydrochloric acid won't help.
poulsbohemian 3y ago
I'm not a metallurgist, but it has been my observation that it deteriorates over time with hot / cold cycles. When I walk into a house built in the 1950s with aluminum pipe, I generally advise homeowners to expect to need to replace it within their time per ownership as my plumber friends have advised it has around a 75 year life at best.

Turing_Machine 3y ago

Classic cast iron drain pipe was connected with by pouring molten lead into the joints after packing them with oakum. Real medieval technology. I'm not super-fond of the so-called "no-hub" joints for cast iron. IMO, the rubber is just waiting to deteriorate underground and cause an expensive nightmare 20 years down the road.

systems_glitch 3y ago
The no-hub also won't carry the weight that hub and spigot cast iron will. I've seen a few roof drains come apart in business ceilings because the old cast iron was replaced with hub and spigot, and no one adjusted the spacing on the clevis hangers. First major rain, and there's too much weight for the no-hub couplings! You can of course run extra heavy no-hub couplers (four or more worm clamps per joint).

jakewins 3y ago

Did some DIY in the US (PEX and PVC), now live in nordics; water pipes here are copper (or PEX). Expensive, but basically just really tiny EMT conduit, so totally fine to DIY.

dredmorbius 3y ago
Guide for the perplexed: DIY: do-it-yourself (fairly widely known) PEX: Cross-linked polyethylene, a form of polyethylene with cross-links. Increasingly prevalent in plumbing applications. PCV: Polyvinyl chloride, a common plastic pipe, often white or black, may be rigid or flexible, widely used in plumbing for decades. "the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene)" per Wikipedia. EMT: Electrical metallic tubing.
- dredmorbius 3y ago
  Erm, that should be PVC, rather than PCV.

amluto 3y ago

Is cast iron really so great for drainage? I get that it’s quiet and has nice mechanical properties, but acidic and/or oxidizing waste seems quite likely to eat it. So your bathroom sink, toilet and laundry are fine, but your kitchen sink? I would much rather use ABS in applications where it works.

systems_glitch 3y ago
The kitchen sink must not be too hard on it, after all it hits the main stack eventually :P I've seen a lot of NY state cast iron cast at the Monitor Iron Works, like Monitor and Merrimack, the US Civil War era ironclad warships. Still in service, still not leaking. Now of course that's survivor bias! You usually don't need expansion joints on cast iron...not that most residential construction gets them even when they are needed. It's detectable in an X-ray, unlike PVC, though I doubt that's of interest to 99% of DWV applications! No-hub is easier to adjust and rework than glued plastic pipe, as you can always loosen the coupling. Hub-and-spigot with rubber gaskets is effectively permanent, you have to seat it with lube and a mechanical assist puller usually. On the old lead and oakum joints, you can always dig out the lead to change orientation (not fun), or caulk it (as in with irons) more if there's seepage on a line.
- amluto 3y ago
  My house had no shortage of cast iron DWV pipes leading from the kitchen that needed replacing. Fortunately they were accessible.
  - systems_glitch 3y ago
    All plumbing ought to be, it all fails. I still have a few more bits of galvanized screwpipe in our current house to replace, but what's left is closed up in walls :/
systems_glitch 3y ago
Cast iron is also not a problem at all to recycle -- it just gets to be woodstoves or brake rotors or more cast iron pipe or something. IMO that is one of its largest strengths as a sustainable building material.