Ductile Iron near boiler piping

D. McLean

I came across a Smith G28A 13 section hot water boiler that had been installed as a replacement (apparently by a plumber) about 9 months ago. They used 6" ductile iron piping on the outlet of the boiler. Is this new technology? I have never seen this done in the 20 years I have been around. comments? Pictures if you want them...

Dave in Kansas City.

mark_40

not new technology ....

he used what he had hangin' around ....plummers ..:-(

D. McLean

Would you replace it?

We are... Just seems like temp swings would be a real problem...

Whatda you think?

Dave in Kansas City

Tony Conner

Pipe Material?

Do you mean carbon steel pipe that has been threaded, and put together with malleable iron or cast iron fittings?

David Efflandt

ductile iron stronger than cast iron

Ductile iron has more tensile (pulling) strength than regular cast iron because instead of irregular graphite flakes, the carbon is reduced to rounder balls. This makes it stronger because stress is less concentrated around balls than sharp edged flakes, and "ductile" means it can more readily deform or stretch, instead of crack as easily as regular cast iron. Steel is stronger than iron because it has even less carbon than iron, but being purer without as much carbon, steel tends to rust more. That is your Materials Science lesson for today.

I am no heating system expert. Just a 1-pipe steam HO, that graduated with a BSME back in 1975, that sells automatic valves in ductile iron, cast steel, bronze, stainless steel, and aluminum.

D. McLean

Ductile Iron

No, it's the stuff plumbers use buried for water, etc. Flanged fittings with lots of bolts. The surface of the pipe is black and textured like an orange. I'll take a pic next week, and post it then.

D. McLean

Thanks

for the lesson. My main inquiry was to find out for certain if it was suitable for use in the boiler piping, 'cause I can't recall ever seeing it before.

Ken_8

Ductile iron is far too

brittle to be used in a steam system. The typical hub gasket is not designed for 215° either.

It's an accident waiting to happen! D.I. pipe fractures (unlike sched. 40) and is not approved for use in steam by any code organization I can refer to.



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Tony Conner

You Can Actually Get...

...ductile iron valves that have a 150 PSIG steam rating. We bought some at the district steam operation I used to work for because you could get a 150# rated valve with a non-rising stem that was good for manhole installations. We never did find a 150# cast steel valve with a non-rising stem. However...the ductile iron piping material that is used for underground water services is NOT made to those standards. I totally agree that ductile iron water piping in this service is a bad-BAD thing. This is the same material that fractures in undergound watermain service during cold snaps in the winter, and has no place in any steam or condensate system. I don't see it standing up to any water hammer at all.

This installation is along the same lines as the 100 HP low-pressure steam fire tube boiler with the safety valve discharge piping done in...wait for it...PVC. Chest high across the boiler room, exiting through a window pane. Even better - it discharged at just about the same height OUTSIDE. A lot of this stuff is so stupid that you couldn't make it up.

D. McLean

Hot Water System

Yea, that's what we were figuring. We are removing the offensive piping starting next week. Even though it's on a water system, it was just too wierd to miss.

bovide_5

ductile

I use ductile iron as a plumber. The joints are called "mechanical joints". As an aside, I doubt if the standard gaskets are designed for >180 deg. temp.

Mijola

Ductile Iron

Dave E,

Your description was great regarding the ductile iron pipe. Given that you obviously have knowledge about that product that we do not have, is it an appropriate product to use in that hot water heating system that Dave M described?

If it is not appropriate would you please describe why, and what problems he would expect to encounter if he leaves it there.


Thanks In advance

Ed Carey

Mijola

Ductile Iron

Dave E,

Your description was great regarding the ductile iron pipe. Given that you obviously have knowledge about that product that we do not have, is it an appropriate product to use in that hot water heating system that Dave M described?

If it is not appropriate would you please describe why, and what problems he would expect to encounter if he leaves it there.


Thanks In advance

Ed Carey
E.A. Carey H.V.A.C.

Mijola

Ductile Iron

Dave E,

Your description was great regarding the ductile iron pipe. Given that you obviously have knowledge about that product that we do not have, is it an appropriate product to use in that hot water heating system that Dave M described?

If it is not appropriate would you please describe why, and what problems he would expect to encounter if he leaves it there.


Thanks In advance

Ed Carey

E.A. Carey H.V.A.C.