Cast iron vs mallable

BillyFris

Is it ok to use mallable fittings instead of cast iron. Looking at some of the pics on here it looks like there using mallable instead of cast unless I’m looking at them wrong.

Jamie Hall

Malleable iron -- if it's the real thing and not a variation on steel -- is tough. Really tough. The advantage of cast is you can break it -- if need be -- with a hammer. Malleable, not a hope. On the other hand, it won't break...

ChrisJ

> @Jamie Hall said:
> Malleable iron -- if it's the real thing and not a variation on steel -- is tough. Really tough. The advantage of cast is you can break it -- if need be -- with a hammer. Malleable, not a hope. On the other hand, it won't break...

Personally I don't feel safe shattering fittings. A grinder is much safer so it doesn't matter if it's cast or malleable.

retiredguy

A good pipe fitter always keeps a 4# hand sledge close by when removing any old steam piping when cast iron fittings are use.. You do not have to be able to turn the fitting or pipe just swing the hammer. my 2 cents

Gordy

Yes it’s okay.

STEAM DOCTOR

Diablo heavy metal sawzall blades are what I use. Cuts through cast iron/mallable like butter. Make 2 cuts, stop before male threads, hammer and chisel. Under 5 minutes. And no sparks or broken grinder wheels to worry about

ethicalpaul

STEAM DOCTOR said:

Diablo heavy metal sawzall blades are what I use. Cuts through cast iron/mallable like butter. Make 2 cuts, stop before male threads, hammer and chisel. Under 5 minutes. And no sparks or broken grinder wheels to worry about

and way less (none) of that nasty burnt metal spark dust

Hap_Hazzard

One advantage of malleable fittings is that they tend to be less bulky. Due to the higher tensile strength, they don't need to be as heavy to prevent fracturing. They also allow you to get a better grip with a pipe wrench. In fact, one way to tell malleable fittings from hard cast iron fittings in old work is the presence of jaw marks.

GroundUp

Local code may dictate what's allowable or not. We cannot use MI on any condensate piping here in MN, it has to be Sch 80 or XH piping and CI or forged fittings. Inspectors typically frown on MI with steam too, but cannot disallow it legally

Hap_Hazzard

I'd love to hear the rationale behind that, if there is one.

EBEBRATT-Ed

@Hap_Hazzard

Yeah, CI is rated 125# steam and malleable is rated for 150# steam so there no good. LOL

I used to use CI because at one time they were cheaper. But as steam goes away a lot of the smaller supply houses only stock MI and since you can't use CI on gas (at least we can't in MA) why bother lugging them around?

Plus I got tired of the wrenches slipping, always wire brushing the jaws and replacing jaws

GroundUp

Condensate is acidic. MI is soft and more susceptible to corrosion. Sch 40 is thinner than Sch 80, more susceptible to wear through due to corrosion.

Hap_Hazzard

GroundUp said:

Condensate is acidic. MI is soft and more susceptible to corrosion. Sch 40 is thinner than Sch 80, more susceptible to wear through due to corrosion.

Crazy. The first thing to rust through is going to be the threads in the mild steel pipe. Even if you re-use fittings (which is probably also too sensible to be code-compliant) you'd go through a half dozen sets of pipes before any of the fittings even got close to rusting through.

Henry

My father would say that it time to play the music. Two solid hits on the seam of a CI fitting, and I could split it in half. I have done some historical restaurations that all the piping was photographed. We used CI fittings and original pipe supports.

Hap_Hazzard

I worry about what's happening to the rest of the pipe joints while you're banging away on those CI fittings trying to break them.

EBEBRATT-Ed

@Hap_Hazzard

Yes, I worry about busting a fitting down the line or causing a leak, especially if the pipe isn't well supported........swinging around.

Depends where it is I usually go for an angle grinder and a cutting disk. I cut both sides of the fitting without getting all the way to the threads then drive and old screwdriver in one of the cuts and they open right up. The cut on the other side allows it to open up easier..........

But everyone has their favorite method

retiredguy

I am older than a lot of you guys so I will tell you how fittings were usually chosen in the commercial/industrial field. Most jobs were done by union steam fitters and they did everything by their "code" which was cast iron fittings on steam pressures up to 150#. A 150# steam boiler job used X-heavy cast iron fittings rated at 250# where the fittings were exposed to the boiler pressure and 125# cast iron fittings on the lower pressure piping and the returns. All the piping below the water line was sch 80 and the piping above the water line was sch 40. Now, I can't tell you what code if any pertains to what type of pipe and fitting to be used but in the jobs I was involved in that is the way it was done and that is the way I was taught. Most of the boilers I serviced were rated at 200# or 150#, high pressure boilers and 15# low pressure boilers. If I was replacing a lot of piping in a steam system and they used cast iron fittings it would take a couple seconds to remove a cast iron fitting with my trusty 4# sledge. You use what you want, I will use my sledge. If you are worrying about down stream pipe or fittings being damaged have someone back you up with an 8#-12# sledge. my 2 cents

Hap_Hazzard

Well, my preference is to unscrew everything and re-use what I can and scrap what I can't. If I absolutely have to break something I use an air chisel, because there's seldom room to swing a sledgehammer, and most of my fittings are malleable. Most things come apart eventually with leverage, determination and sheer brute force.

GroundUp

Well, I can tell you there have been several dozen occasions of me replacing rotten MI fittings in systems less than 10 years old in my short 6 year career with steam. Many were Sch 40 which still looked perfect, but MI elbows were paper thin and pinholed. I see it a lot. Did a YMCA building last spring that was only 4 years old and pretty much repiped the entire condensate side of the system because most of the MI fittings were pinholed or cracked. There's a reason condensate pumps are cast instead of mild or malleable

ChrisJ

GroundUp said:

Well, I can tell you there have been several dozen occasions of me replacing rotten MI fittings in systems less than 10 years old in my short 6 year career with steam. Many were Sch 40 which still looked perfect, but MI elbows were paper thin and pinholed. I see it a lot. Did a YMCA building last spring that was only 4 years old and pretty much repiped the entire condensate side of the system because most of the MI fittings were pinholed or cracked. There's a reason condensate pumps are cast instead of mild or malleable

Sure, cast is cheap and it doesn't need the strength of steel.

I can only imagine the cost of a billet steel condensate pump......

It may be true between ci and mi fittings but you can't say it for steel vs cast iron in general. When it comes to pumps I'm pretty certain it's because cast is cheap and gets the job done.

GroundUp

Forged fittings are cheaper than cast, I would beg to differ the reasoning behind cast pumps and receivers is solely cost driven

ChrisJ

> @GroundUp said:
> Forged fittings are cheaper than cast, I would beg to differ the reasoning behind cast pumps and receivers is solely cost driven

Ok

EBEBRATT-Ed

@GroundUp

I don't see forged steel being cheaper

From Supply House .com
2" elbows

CI $10.36
Malleable $11.55
Forged Steel $15.19

GroundUp

EBEBRATT-Ed said:

@GroundUp

I don't see forged steel being cheaper

From Supply House .com
2" elbows

CI $10.36
Malleable $11.55
Forged Steel $15.19

Odd. The supply house (Ferguson Enterprises) I buy all my commercial material through is quite different. MI is cheapest by a large margin and forged is about 10% less than cast. Maybe there's a mix and match with brands and whatnot but I always spec domestic versus import so it should be apples to apples. I've been on hot and chilled water for quite awhile, I think the last steam job I did was that YMCA but I had ordered everything in CI and my rep called to tell me it was considerably cheaper to buy forged. I don't remember exact numbers but I'm certain it was right around the 10% neighborhood. I thought it was weird too, given the manufacturing processes of each, but that was the case for me.

ChrisJ

> @GroundUp said:
> (Quote)
> Odd. The supply house (Ferguson Enterprises) I buy all my commercial material through is quite different. MI is cheapest by a large margin and forged is about 10% less than cast. Maybe there's a mix and match with brands and whatnot but I always spec domestic versus import so it should be apples to apples. I've been on hot and chilled water for quite awhile, I think the last steam job I did was that YMCA but I had ordered everything in CI and my rep called to tell me it was considerably cheaper to buy forged. I don't remember exact numbers but I'm certain it was right around the 10% neighborhood. I thought it was weird too, given the manufacturing processes of each, but that was the case for me.

That's probably due to volume. They don't sell near as many cast.

Hap_Hazzard

Does anyone know what types of cast iron are used in cast and malleable fittings? I know the malleable fittings are annealed white cast iron, and the cast fittings are gray, but there are several types of each.

EBEBRATT-Ed

Supply House.com had cheaper fittings the prices above were for domestic fittings

dopey27177

Here is the story about malliable fittings.
They are also cast. The difference between the cast iron fitting and the malliable iron fitting is cast fittings have a lot of carbon in them making them hard and somewhat brittle.
Malliable iron fittings have very little if no impurities in them and that makes them ductile, softer and in some regards stronger.

Cast iron fittings cannot be used on any type of gas because they a re some what porous, the cast iron fitting can be used any system that has water or water vapor in it because the pourosity vanishes when the internal rusting process begins.

A little history about MI fittings rotting out.
I only used Ward fittings and Grinnell fittings never had a problem.

In the early 1970s pipe and fittings were imported from China, these materials were never sent for testing to ASTM and given a
an approval for use in the USA.

The cost of this material was 30% less than american made products.

Many small pipe contractors bought this junk because they could not compete with more reputable contractors.

So when you speak about what fittings or pipe is better than the next product see if your pipe has a schedule rating on the pipe or if your fittings are listed with ASTM by manufacturer.

Remember one thing about materials in the pipe trades.
What is this material usage intended for. Or, What was specified by the customer.

It is your responsibility to use the appropriate material for the type of job you are doing.

MI is ok for steam if you can afford to unstall it, I will still recommend Cast iron fittings for steam and in some cases water.

Remember this too. Many water main shut off valves are made from the same cast iron that the cast iron fittings are made of. (this applies to only made in the USA)

Jake

EBEBRATT-Ed

@dopey27177

I think water main valves are ductile iron which is similar to Malleable

Hap_Hazzard

Jake, it's not the amount of carbon that distinguishes white iron from gray. It's the form it takes when the iron is cast. In gray iron, the carbon precipitates as graphite. In white iron it precipitates as pearlite or cementite. White iron is very brittle, but after annealing its tensile strength is greater than gray cast iron.

Hap_Hazzard

I think ductile iron is more similar to gray cast iron, except the graphitic inclusions are spherical instead of precipitating as flakes, but it's properties are more similar to pearlitic white iron, but it's less brittle and more ductile because the spherical inclusions are graphite instead of carbide.

dopey27177

The chemistry lesson was great. It brought me back to my classes in strength and materials. (60 years ago) You are refreshing my memory.

But in lay mans terms cast iron fittings are brittle, malliable iron fittings are not.

I do not know how old you are but like I said in the early 70s many fittings came into this country from China.

We used ward and grinnel fittings never had a problem. Cast iron broke nicely down the seam when hit with a 3 pounder malliable fittings were re-usable and did not leak when lamp wick was used on the threads of pipe and nipples.

When I say re-usable I mean the fitting was on the existing pipe and we were making a repair or cutting a "T"nearby.

We did not play the salvage game.


Jake

ethicalpaul

I don't blame contractors for not re-using materials. They would have to spend labor $$ to do so, so why not use those same $$ (or even fewer!) to have new stuff and free up your labor to get to another job faster.

But as a H.O. I love reusing 100 year old Ward CI fittings on my system

Dave0176

> @ethicalpaul said:
> I don't blame contractors for not re-using materials. They would have to spend labor $$ to do so, so why not use those same $$ (or even fewer!) to have new stuff and free up your labor to get to another job faster.
>
> But as a H.O. I love reusing 100 year old Ward CI fittings on my system

I don’t reuse fittings for that exact reason, it takes time to cape the old pipe nipples out, then I gotta chase the threads. It’s just easier to reach in the bin a grab a new fitting.

As far as cast vs malleable, I like cast, I like the look of it, it’s what the old timers used, to me cast iron and steam just go together and in my opinion it just looks tough......

My local supply house carries pretty much everything up to 4” in both cast and malleable in Ward fittings.

I’ll use Anvil too if I have to, Anvil has the old Grinnell line of fittings.

And I am also one to use cast fittings even on hot water baseboard near boiler piping. I just like the look..... My personal opinion