Why Some Steam Boilers Fail - A page turner - White Paper

Bruce Stevens_2

non-pin three pass

Gary Hayden_2

Why Some Steam Boilers Fail - White Paper

Arrived by US Mail today - Just finished a page turner -

I suggest that this article / piece will be one of the most referenced articles by boiler manufacturers and their reps / salesman. Commonly known as a "White Paper".

If anyone has a link to this to put up here- or find a copy of P&M March 2008 / Volume 26 Number 1

DanHolohan

It's in

Hot Tech Topics

Thanks, Gary.

Big Will

how old is the wall

I have been looking and posting for about 2 years but I know its older than that.

DanHolohan

It's 10 years old.

John@Reliable_14

Only 10 Dan?

Time does fly, doesn't it. John

Dave Yates (GrandPAH)

after reading the article........ (GrandPAH)

After reading about meds in our public water systems, it's no stretch to imagine some PPB-level of road-salts might be hitching a ride too.

Pins vs. no pins? I'm stretching my feeble brain trying to recall boilers without pins that we've installed in recent years. Are there models that remain pinless???

How much of an eff bump do the pins grant??? Seems like a double-edged sword: we demand higher efficiencies, yet that causes minute amounts of salts to become a boiler-killer.

Cast without pins above the water line???

As for the super-heated heat-transfer from pins: what is the temperature boundry line? That's info I'd like to have that's not included in the article.

If a boiler & its steam system are tight (free of leaks) and the water is recycled through heating cycles, does the salt lose its aggressive qualities while attacking the iron or does it re-dissolve and return to repeat its destructive cycle?

Is there a simple filtration canister that can be added for feed-water that will absorb salts?

I get the metering deal & we always recommend one. Testing too. I gather the salt levels we're talking about would defy being discovered with entry-level test instruments at such low concentrations???

Given that my area utilizes water collected from surface run-off and streams, I'm wondering why this has not been an issue we've seen & we do a ton of steam???

DanHolohan

I don't know

the acceptable temperature for the pins above the waterline, Dave, but I believe it would depend on the amount of chlorides in the water. And I don't know the acceptable level of chlorides in a steam boiler. I haven't been able to get any of the manufacturers to say what that is.

Dave Yates (GrandPAH)

what I don't get

could fill the library of congress books - ten fold!

Stuppose we boil water under 1-Lb of pressure = 215F, right? In the short and fast(er) move from new-born-steam to moving-out-the-outlet, how much hotter can that cast iron get???? It is, if my mind is functioning properly, a wetted surface by virtue of the fact that we need a header beyond the boiler to wring out larger water droplets? So, now I'm wondering what kind of delta-T we might see from base of section to top of crown and then that data divided by where the water and steam is within the section as well as those temps over the pinned portion (from bottom to top). Wondering ..... if the liquid must be 215F to boil & we base our rads EDR on that same 215F, what is the temp within the steam chest???? And, what is the temp of the CI wall over the two areas - both externally and internally, although it seems the stool-sitter indicates the issue is at, or borders on, the water-line internally.

I'd sure like to hear from the mfgrs on this issue. My e-mail is above if privacy is wanted.

DanHolohan

I believe it has to do with

the liquid being able to absorb more heat from the metal pins than the steam can absorb from the metal pins. The liquid is on its way to becoming steam, which requires lots of heat. The steam is already there and not absorbing any more heat, well, not enough to make a difference.

Dave Yates (GrandPAH)

interesting link

http://www.aquapurefilters.com/contaminates/118/chloride.html

Well, we can rule out RO as a means!

Here's another one:

http://repositories.tdl.org/handle/1969.1/446

Maybe an anode rod for steam boilers could be developed????

ttekushan_3

boiler leak

Yeah, but what kind of glue should I use to fix this one?

-Terry

[Deleted User]

\"none of them had pins.

They had smooth, ribbed surfaces and a lot more metal...."

so then, why don't the manufacturers go back to the older design?

Mark Eatherton

My $0.02 worth

That is obviously not any where near the water line. That's in the upper reaches of the steam chest. A search of "graphitic corrosion in cast iron" shows that the occurrence of this type of corrosion is NOT exclusive to hot, heated surfaces.

I suspect, based on field observations, that in the process of becoming more efficient at developing cast iron casting technology, that the boiler manufacturers have made the thickness of the cast iron much thinner, resulting in less time before vessel failure. The old cast iron boilers that I have had the opportunity to take apart were massively thicker than todays cast iron sectional boilers.

That is not to say that the addition of chlorides will not cause early or faster failure, but I suspect that thickness has as much if not more to do with the early failure of todays modern boilers. Any one who has had the task of taking apart an older snowman type of boiler knows exactly what I am talking about. I think that the same elements were at work on these vessels as well, it just had a LOT further to go before leaking through.

Just my two cents worth. You want your change back? :-)

ME

JackR

Out of luck

I think everything out there right now is a pin style, looks like we will be seeing a lot more corrosion.

Phil_17

[Deleted User]

Many of the failures

I see, that cannot be attributed to excess fresh water, are in the upper area of front sections, above the pins.

The other most prevalent area is the top of intermediates, above the pins.

Very few failures in the pinned areas.

JackR

Never Thought of them

Looks like they might be way ahead of the curve with that

[Deleted User]

yeah...now all they have to do is...

set it up on gas and modulate it down when necessary, and steam just MIGHT be as efficient as other hydronic alternatives...

Mr Lochinvar, meet Mr Burnham...

You just never know. Whooda thunk that Ford would own Volvo and all the other Europeans.

You never thought that Molson and Coors would end up under the same roof either did you. How's about Molson, Coors, Pabst...

ME

Bruce Stevens_2

Good Idea

however a hi lo oil burner would be a great start