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Malleable or Cast Iron fittings?

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Sorry to beat this topic to death!

I'm in NYC, what fittings for steam please? I see companies selling near pipe kits and it all looks malleable. I'm thinking malleable. Thanks!

Comments

  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,840
    edited February 2022
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    Either will work. Stay away from Galv.

    Time was, (before that new fangled copper pipe) Cast cost less than malleable. The Gas company did not like the way Cast could crack on impact so they liked the more expensive malleable fitting. Today there is a lot less use for cast so the malleable fittings are near the same cost.

    So, if you can get a good deal on Cast for a steam job. Go for it. It can be hard to find at local supply companies.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    ranzerox
  • gerry gill
    gerry gill Member Posts: 3,078
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    Cast when availability allows, otherwise malleable out of necessity.
    gwgillplumbingandheating.com
    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

    ranzerox
  • ranzerox
    ranzerox Member Posts: 52
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    Can I use #150 or #300, thanks!
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
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    Honestly, I've only seen those ratings for flanges, where load-bearing is critical. As long as you're buying schedule 40 fittings, you should be okay.

    BTW, I use maleable fittings because it's easier to get a pipe wrench to bite on them.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
    JUGHNEranzerox
  • STEAM DOCTOR
    STEAM DOCTOR Member Posts: 1,973
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    NYC code allows both. Malleable is lighter, smaller (OD) and easier to work with. Only real benefit to cast, is that it's easier to crack ( in event you need to remove in the future). In this day and age, with grinders and all sorts of saws and blades, this should not be much of a consideration. 
    reggiethicalpaulHap_Hazzardranzerox
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,529
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    I see no benefit to CI any longer. Most small supply houses don't stock them. Malleable is rated for higher steam pressure (124 v 150) and you can use them on gas...less stock.

    Less likely to have a pin hole in malleable
    ranzerox
  • ranzerox
    ranzerox Member Posts: 52
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    If I go with malleable, which pressure rated should I go with? Here's a picture of a fitting I'm considering using versus one rated for 300. Thanks




  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
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    Only real benefit to cast, is that it's easier to crack ( in event you need to remove in the future). In this day and age, with grinders and all sorts of saws and blades, this should not be much of a consideration.

    Also, if you use a pipe joint compound with PTFE you'll never have to worry about taking joints apart. I love the stuff.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
    ranzerox
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
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    ranzerox said:

    If I go with malleable, which pressure rated should I go with? Here's a picture of a fitting I'm considering using versus one rated for 300.

    Interesting. I've never seen a pressure rating on a fitting before. Maybe they were there and I never noticed.

    Since steam systems typically operate at 3 psi or lower, it's not really anything to worry about. The safety valves open at 15 psi, so 300 psi is 20 times the highest possible pressure they could see. Since I'm not a pro, maybe I just haven't seen one break due to pressure, but I'd be really surprised if anybody else has. I'd expect the pipe to split along the weld long before a fitting exploded. I'd say go with whichever is cheapest, all other things being equal.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
    ranzerox
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,529
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    Standard CI and Malleable fittings are usually not marked with a pressure rating. But it's widely known that Cast Iron has a steam rating of 125# and malleable has a steam rating of 150#. That's all you need for a 15# rated system.

    XH cast iron is rated 250 lb and xh malleable (usually called ductile iron) is rated 300#
    Hap_Hazzardranzerox
  • cubbydog
    cubbydog Member Posts: 42
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    It’s only a matter of time until cast goes the way of the horse 🐎 n buggy. The only thing that cast has over malleable iron is it cracks, that doesn’t matter these days.
    The cost is so close and once they stop making cast, malleable will go down in price.
    ranzerox
  • PC7060
    PC7060 Member Posts: 1,160
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    ranzerox said:
    If I go with malleable, which pressure rated should I go with? Here's a picture of a fitting I'm considering using versus one rated for 300. Thanks   
    What ever they sell at SupplyHouse.com.  Go for the Ward brand if you want US made.