Black pipe on potable water

doug_piazza

I work as a power pant operator in a very large hotel . This building has just been commissioned in December of 2010.

My question is Can you use BLACK PIPE on your main water supply to your boiler fed tank. This boiler feed tank feeds 2- 40 Horse power steam boilers running at 160 psi.. We are at 90% fresh make up water. the 3 -500 horse power boilers I do care so much about because we aren't added water to them every day. The installing contractor said that they always pipe the fresh water make up to the  feed tanks and boiler connections with black pipe. this worries me.Fresh water has a lot of oxygen which equals rust. I've been in the heating business for 35 years and I know that black pipe  and fresh water doesn't mix. just need someone else to give me some feed back .

Thanks

Doug Piazza (formally from Long Island New York)

These people really need to learn what a good heating system is and Scorched Air is not the way to go.

Utah - The Land Of Scorched Air

dougpiazza@yahoo.com

meplumber

Is this between a DA (deareating) tank and the boiler?

Many systems of this size, with this amount of make up water, use a deareating tank.  Black iron pipe between the DA tank and the boiler is an accepted practice due to the higher water temps found in the DA tank, copper is not advised, and a fair amount of the dissolved O2 in the water (the corrosion culprit) is removed in the tank.



However if this piping you are referring to is directly from a cold water line and the boiler, then I personally would not use black iron.  It would depend on local and state codes as to whether it was "illegal".

doug_piazza

Black pipe

thses water lines are the lines used to fill the DA Tank. and yes the piping from the DA to the boilers are black pipe. My main consern is the water lines feedind the DA tank.

Thanks

doug_piazza

Black pipe

thses water lines are the lines used to fill the DA Tank. and yes the piping from the DA to the boilers are black pipe. My main consern is the water lines feedind the DA tank.

Thanks

meplumber

I understand you concern.

With this being a newly comissioned building, the power plant was almost certainly designed by a licensed Professional Engineer.  If the engineer specified black iron pipe from the domestic water supply to the DA tank, then the installer had to install as specified.  The purpose for having "stamped" plans is to lean on the learned ones.



Black iron pipe has been carrying water for longer than you and I have been alive.  There has been a push in the industry to move away from galvanized piping due to a whole host of other concerns. Copper may not be appropriate due to other outlying factors. If the system was designed by a PE, and I am sure that it was, then just go with it and trust their judgement.



If you find the plans and see that the PE specified something other than black iron, then you can ask the installer to install as specified.



Good Luck

doug_piazza

black pipe

Thank you!

icesailor

Black Pipe on Boiler:

You can bet your sweet black pipe that there is a reduced pressure zone back flow preventer that is piped in Copper or some other potable water approved pipe. What happens after the backflow is of no concern of any plumbing code. As ,long as the integrity of the potable water for human consumption is protected, it's OK. What it may or not do to the heating system is between the boiler and the engineer who designed and spec'ed it.

You will find no unprotected steel pipe in a potable water system. You may find it in an automatic fire sprinkler system but that is protected by a backflow device.  

Brad White

Exactly right, Icesailor.

The raw make-up water would be in type L copper, but after that, black iron (usually ASTM B53 carbon steel) is typically used, especially where chemical treatment is used and being after a deaerator. It is, as icesailor said, separated by an RPZ backflow device.



When you consider all of the pipe handing condensate, vents, steam and boiler feed water, being iron is not of much concern. Protecting the potable water supply, is.

Brad White

I do have to ask,

for a power plant, why so much make-up water? 90 percent? I gather from those pressures you are serving laundry process, maybe kitchen cooking appliances and of course HVAC. Maybe even some low pressure electrical turbines for cogeneration. But all of these have minuscule make-up water requirements. Nearly all of the water can be returned as condensate and not dumped.



So, I am just a bit curious!

icesailor

Returning Condensate:

Yeah Brad,

Throwing away used condensate is like standing in a windstorm with buckets full of dollar bills and peeling them to the wind.

Let me see, how does trhat work? A gallon of water weighs 8.33#, it starts at 50 degrees? How many BTU's to heat it up to boil? How much is lost by throwing it away? How much is saved by recycling the hot condensate?

I think it is a lot.

Put the most efficient power plane in that you can. Then dump the condensate water and not recycle it.

Oh well, Ther're smart. I'm not.

Mark Eatherton

Screw the code... Whatever happened to employing COMMON SENSE???

Even if it IS after an RZP, but before deaeration or treatment, it NEEDS to be of non ferrous nature. If not, it WILL go away, like a red headed step child with freckles AND pimples...



Just because the engineer drew it that way doesn't mean that it is right, and if the contractor KNEW that and didn't bring it to the attention of the engineer, he too may be culpable.



ME

meplumber

Been there Mark.

At one point in my career, I did a lot of these huge commercial systems when I was a union man.



Every time we brought something like this up to the engineer we got the same song and dance, "You change it, you own it."



The larger the job the more arrogant the engineers seem to get.



I agree, but what do you do when it is a set of stamped prints?

I don't like ferrous piping on the input side of the DA tank.  I have seen stainless run where there were outlying factors against copper.  As ice and Brad stated the plumbing code stops at the RPZ and the boiler, steam and ASME codes take over.



The catch is getting the insurance companies to buck the PE's.  Not gonna happen.

meplumber

Been there Mark.

At one point in my career, I did a lot of these huge commercial systems when I was a union man.



Every time we brought something like this up to the engineer we got the same song and dance, "You change it, you own it."



The larger the job the more arrogant the engineers seem to get.



I agree, but what do you do when it is a set of stamped prints?

I don't like ferrous piping on the input side of the DA tank.  I have seen stainless run where there were outlying factors against copper.  As ice and Brad stated the plumbing code stops at the RPZ and the boiler, steam and ASME codes take over.



The catch is getting the insurance companies to buck the PE's.  Not gonna happen.

Mark Eatherton

You CYA in paper...

Document the infraction, mail a copy of it to the GC, and the engineer of record. If at some point down the road, the owners decide to go back and sue someone, your butt is covered in paper. If the engineer of record decides he is right and you are wrong, then HIS errors and omissions policy will be imposed upon, not your GL policy.



If you look real close at the drawings and specifications, it clearly states that if you see something in the engineers work that is wrong, and you don't immediately bring it to their attention, then you are culpable for any costs associated with the fix.



As a judge once told me, if it is not in writing, in the eyes of the court, it doesn't exist.



Proceed with caution. Tis a litigious society in which we live.



As for the insurance companies, they employ their OWN PE.s ME's and even have some engineers with law degrees. I've worked side by side with these folks, and they are a VERY intelligent bunch.





ME

Gordy

Then you CYA

 If you bring it to the designers attention, and he is adamant he is right. Then you CYA, and are off the hook.  Some paper work to verify the RFI is a must, and sometimes will lead the adamant headed designer to re think their logic.



Gordy

Gordy

sorry Mark

 Must have been posting at the same time.

Mark Eatherton

Great minds think alike Gordy :-)

We even used the same acronym ;-)



ME

Brad White

But....

The reason the steam side is piped in carbon steel is the same reason you do not pipe steam in copper: Stresses of expansion and contraction including pump-on/pump-off thermal and dynamic stresses would tear copper apart sooner or later.



But this also underscores the need for de-aerators in steam systems with lots of make-up water. Pre-heating and driving off non-condensibles, free air and chemistry off-gassing, is the key to pipe longevity.

Mark Eatherton

Agreed and understood Brad....

and just in case it was not clear, I am addressing the make up water between the source of supply and the de-aeration assembly.



Also, my comments regarding engineers is not meant to defame these VERY necessary folks. Engineers (most of them anyway) are human beings, and as such are subject to mistakes.



We all make mistakes. To err is human...



If I make a mistake, I fix it, at my expense.



ME

Brad White

We agree, Mark

You can drink from the protected copper side. That is code everywhere I know, IPC and elsewhere. Ductile iron is acceptable in the street of course. Funny how that works out! As if the last run to your house has amazing cleansing properties.