Malleable or Cast Iron fittings?

ranzerox

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!

EdTheHeaterMan

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.

gerry gill

Cast when availability allows, otherwise malleable out of necessity.

ranzerox

Can I use #150 or #300, thanks!

Hap_Hazzard

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.

STEAM DOCTOR

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. 

EBEBRATT-Ed

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

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

STEAM DOCTOR said:

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.

Hap_Hazzard

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.

EBEBRATT-Ed

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#

cubbydog

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.

PC7060

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.