Municipal Water Treatment for Steam Boiler?

AdmiralYoda

I live in a town that treats their own municipal water from a large reservoir. Below are a couple comparisons from the latest water quality report to the requirements from my Peerless Boiler.

Municipal Report:
Chlorides: 30.7ppm
pH: 8.08
Hardness: 15.5

Peerless Manual:
Chlorides: <30ppm
pH: 7.5-11
Hardness: <7

My total dissolved solids are 108ppm if that makes a difference. Peerless doesn't mention a requirement for this.

So overall my municipal water isn't too bad, though it looks like I could soften my water a bit. I add Rectorseal 8-way to keep the pH around 10 or so. Water is crystal clear in my 42 year old Peerless.

But out of curiosity, should I decide to treat the boiler water or the whole house supply for that matter... what would be the best way to go about this? I admit I know nothing about water treatment.

Jamie Hall

There's nothing wrong with your municipal water in terms of using it for a boiler. Just use it as is -- don't treat it. Particularly, don't even think of softening it -- that will send the chlorides out of spec.

You could soften your domestic water, if you like. You shouldn't need to, but some folks like slippery water. You would do that anywhere after the take off for the boiler. I'd use a plain vanilla ion exchange water softener if asked to do the job (I wouldn't, myself -- I dislike the feel of softened water, but that's just me).

ChrisJ

Hmmm.

@Jamie Hall
How about my water?

Jamie Hall

not real happy about those chlorides there.... not that there's much you can do about it.

WMno57

Water softeners are bad for boilers. They replace calcium and magnesium with sodium. Calcium and magnesium will plate out as scale in your boiler. This is good. Sodium is inversely soluble in relation to temperature and will stay in solution where it raises the electrical conductivity causing corrosion.
If it were mine, once a year I would drain the boiler and fill it with Wal-Mart distilled water. I would still use 8 way. I would still use municipal water for make up. Doing this would reduce the hardness and chlorides.

ChrisJ

Jamie Hall said:

not real happy about those chlorides there.... not that there's much you can do about it.

So,
Is that considered hard water? Is it corrosive?

Would a softener be beneficial for everything but the boiler?

Jamie Hall

No, it's not hard -- I didn't see the calcium and magnesium results? So I really can't tell.

But -- the chlorides indicate it is a little more corrosive than i would really like... tell your highway department to lay off the road salt.

ChrisJ

Jamie Hall said:

No, it's not hard -- I didn't see the calcium and magnesium results? So I really can't tell.

But -- the chlorides indicate it is a little more corrosive than i would really like... tell your highway department to lay off the road salt.

Oh they love the salt!

Check your PM. I sent you the entire report. I also kinda don't like hijacking this thread, but I thought my info may be a good comparison for the OP.

AdmiralYoda

@ChrisJ Hijack away! We are essentially asking the same question!

@Jamie Hall Here is my full water quality report. Anything stick out to you? Thanks!

ethicalpaul

There's nothing wrong with your municipal water in terms of using it for a boiler. Just use it as is -- don't treat it.

Or, yes, keep treating it with 8-way to get the ph up to the manufacturer recommendation. Jamie's boiler has like 8" thick castings, so he doesn't worry about PH, but the rest of us do

vhauk

The corrosive nature of water is extremely complex, having to do with tds, the balance between ph and hardness, and so on, and so on. Oxygen content is high on the list, because you can’t form iron oxide (rust) without oxygen. 

ethicalpaul

The oxygen goes away on its own, the ph doesn't

vhauk

Every time the main vent opens, oxygen flows back into the system. Water likes having oxygen in it. Contact with atmosphere is all it takes to oxygenate water. Ph’s relationship to corrosion is much more complex that less is bad and more/higher is better. It’s possible to have a high 8.0 and higher ph and have extremely corrosive water. Apologies I’m not trying to be argumentative. 

ChrisJ

vhauk said:

Every time the main vent opens, oxygen flows back into the system. Water likes having oxygen in it. Contact with atmosphere is all it takes to oxygenate water. Ph’s relationship to corrosion is much more complex that less is bad and more/higher is better. It’s possible to have a high 8.0 and higher ph and have extremely corrosive water. Apologies I’m not trying to be argumentative. 

That's literally what I keep trying to tell everyone but no one listens.
The entire system is open to the atmosphere and pulls fresh air in every time it shuts off.

Why everyone thinks dissolved O2 is only an issue with makeup water has confused me for years. I don't know much about the subject, but I've had quite a few that do understand it tell me O2 is always going to be a concern in a vented steam system and that makeup water isn't going to be the main source.

Jamie Hall

Quite true, @vhauk . However, the effect on oxygen levels in the boiler water is, while not perhaps negligible, minimal. In order to get any significant amount of oxygen into water -- something the wastewater and aquarium boys pay a lot of attention to -- takes a good deal of vigorous interchange between the air and the water. However, in a boiler, there is only a very small amount of air actually in contact with the water, and there is no appreciable circulation at all, either of the air or the water. You are completely dependent on diffusion processes, which are remarkably slow.

If it were a concern -- it isn't -- you would expect to see extensive corrosion in the steam mains themselves, where there will be air drawn in and residual water. You don't.

Now if you add water to the boiler with a decent oxygen saturation, then yes -- there will be corrosion, at least until the initial fill is boiled and the oxygen levels dropped essentially to zero. That's why it is important to find leaks, so you aren't doing that all the time.

WMno57

Agree with Jamie that diffusion is minimal. An example of this would be the air over water expansion tank in my hot water heat system. 105 year old gravity pipes and 75 year old boiler.

vhauk

There are 2 main reasons for corrosion. One is galvanic and the other chemical. Galvanic happens because of electrons flowing through the water. Electrical current. All fresh water has oxygen otherwise it is septic. Steam mains don’t corrode because steam replaces any air which contains the oxygen. 

vhauk

An Air Force maintenance officer overlooked the effects of corrosion in an elevated water storage tank. The level of water in this tank was never varied for years. A strong wind took the top of the tank off at the water level and set it on several parked cars. The corrosive action of water and air in the same spot literally cut the tank in two. Expansion tanks are constantly changing water level. Aquariums have critters living in them using the oxygen and converting it to co2. Wastewater treatment plants have large colonies of bacteria that live on the sewage but need vast quantities of oxygen to survive and treat our waste. Hence mechanical aeration. 

ChrisJ

vhauk said:

An Air Force maintenance officer overlooked the effects of corrosion in an elevated water storage tank. The level of water in this tank was never varied for years. A strong wind took the top of the tank off at the water level and set it on several parked cars. The corrosive action of water and air in the same spot literally cut the tank in two. Expansion tanks are constantly changing water level. Aquariums have critters living in them using the oxygen and converting it to co2. Wastewater treatment plants have large colonies of bacteria that live on the sewage but need vast quantities of oxygen to survive and treat our waste. Hence mechanical aeration. 

Allegedly when you boil water it drives the oxygen out.
Does it have to boil, or is there a specific temperature it happens at?

If it needs to boil, does that mean as it drops below boiling point it starts absorbing again?

How do chemicals used as oxygen scavengers work?

vhauk

Allegedly when you boil water it drives the oxygen out. Does it have to boil, or is there a specific temperature it happens at? If it needs to boil, does that mean as it drops below boiling point it starts absorbing again? How do chemicals used as oxygen scavengers work?

York Shipley recommends on their steam pack boilers to heat the boiler water to 180 to drive out excess oxygen after performing the wet side maintenance. Water has a varying natural level of oxygen depending on temperature and pressure, and several other things. If you drive out most of the dissolved oxygen then as soon as the water is exposed to free oxygen it will absorb it quite readily. In other words, yep. 

vhauk

Anything that combines with the d.I. will bind it so that it won’t react. Oxygen binding chemicals. 

ChrisJ

vhauk said:

Anything that combines with the d.I. will bind it so that it won’t react. Oxygen binding chemicals. 

How is Sodium Nitrite at that?

vhauk

we use used sodium nitrate at the plant I operated in out hot water system as a corrosion inhibitor, it forms a protective barrier on ferrous surfaces. 

ChrisJ

vhauk said:

we use used sodium nitrate at the plant I operated in out hot water system as a corrosion inhibitor, it forms a protective barrier on ferrous surfaces. 

Once that barrier is there, does sodium nitrate need to remain in the water or would that barrier stay even if sodium nitrate was removed?

vhauk

ChrisJ said:

we use used sodium nitrate at the plant I operated in out hot water system as a corrosion inhibitor, it forms a protective barrier on ferrous surfaces. 

Once that barrier is there, does sodium nitrate need to remain in the water or would that barrier stay even if sodium nitrate was removed?

We had a feeder. (13.5 acre building) While acting like a barrier it’s really an anode type of barrier. So the barrier would be a sacrificial anode. So yes, it needs to be added on some basis, just like anodes have to be replaced. 

Jamie Hall

Mountains out of molehills. Yes, water with moderate to high levels of dissolved oxygen will promote corrosion. Is this a problem? Well, it depends. If you are running a large power boiler -- say somewhere around 50,000 boiler horsepower -- it surely is. If you are running a teakettle, it isn't. At what point do you start to worry about it? And at what point do other considerations start to be more important, such as chlorides or any of a number of other ionic species or excess pH levels (in either direction -- basic or acidic, by the way). At what point are galvanic effects more important? And then there is the question of what metals and alloys are you worried about? Cast iron? Malleable iron? low carbon steels? Stainless steels (better find out what alloy)? Aluminium (again, what alloy)? Copper?

There are a number of compounds which can be used to protect against corrosion. Some are for steam boilers. Some are for hot water systems. Some are used in public water supplies. Some are intended for boilers during shutdowns. And so on. If you have managed to convince yourself that simply making sure your dissolved oxygen levels are under control, and the pH is reasonable, and you are running even a very large residential boiler. Relax. Don't worry about it. If you're still worried, there are engineering services which will be happy to help you find the perfect concoction for your needs.

ChrisJ

Jamie Hall said:

Mountains out of molehills. Yes, water with moderate to high levels of dissolved oxygen will promote corrosion. Is this a problem? Well, it depends. If you are running a large power boiler -- say somewhere around 50,000 boiler horsepower -- it surely is. If you are running a teakettle, it isn't. At what point do you start to worry about it? And at what point do other considerations start to be more important, such as chlorides or any of a number of other ionic species or excess pH levels (in either direction -- basic or acidic, by the way). At what point are galvanic effects more important? And then there is the question of what metals and alloys are you worried about? Cast iron? Malleable iron? low carbon steels? Stainless steels (better find out what alloy)? Aluminium (again, what alloy)? Copper?

There are a number of compounds which can be used to protect against corrosion. Some are for steam boilers. Some are for hot water systems. Some are used in public water supplies. Some are intended for boilers during shutdowns. And so on. If you have managed to convince yourself that simply making sure your dissolved oxygen levels are under control, and the pH is reasonable, and you are running even a very large residential boiler. Relax. Don't worry about it. If you're still worried, there are engineering services which will be happy to help you find the perfect concoction for your needs.

I'm not worried.
I pop two Steamaster pills in and the water turns purple and rust stops happening, at least in the boiler the best I can tell. Remember, the main ingredient in Steamaster is Sodium Nitrite.

I'd be very worried with straight water though. I saw that rusty chocolate milk in my gauge glass for a few months when I put the boiler in.

AdmiralYoda

ChrisJ said:

I'm not worried.
I pop two Steamaster pills in and the water turns purple and rust stops happening, at least in the boiler the best I can tell. Remember, the main ingredient in Steamaster is Sodium Nitrite.

I'd be very worried with straight water though. I saw that rusty chocolate milk in my gauge glass for a few months when I put the boiler in.

I think SteamMaster Tablets are discontinued right? I've been using Rectorseal 8-way with good results. It looks like the active ingredients are Sodium Phosphate, Sodium Hydroxide and Sodium Nitrate. Maybe its a similar product.

reggi

AdmiralYoda said:

I'm not worried. I pop two Steamaster pills in and the water turns purple and rust stops happening, at least in the boiler the best I can tell. Remember, the main ingredient in Steamaster is Sodium Nitrite. I'd be very worried with straight water though. I saw that rusty chocolate milk in my gauge glass for a few months when I put the boiler in.

I think SteamMaster Tablets are discontinued right? I've been using Rectorseal 8-way with good results. It looks like the active ingredients are Sodium Phosphate, Sodium Hydroxide and Sodium Nitrate. Maybe its a similar product.

Potato Potatoe 😊

Rectorseal 68732 36 Steamaster Tablets https://a.co/d/ftusp89

ChrisJ

reggi said:

AdmiralYoda said:

ChrisJ said:

I'm not worried.
I pop two Steamaster pills in and the water turns purple and rust stops happening, at least in the boiler the best I can tell. Remember, the main ingredient in Steamaster is Sodium Nitrite.

I'd be very worried with straight water though. I saw that rusty chocolate milk in my gauge glass for a few months when I put the boiler in.

I think SteamMaster Tablets are discontinued right? I've been using Rectorseal 8-way with good results. It looks like the active ingredients are Sodium Phosphate, Sodium Hydroxide and Sodium Nitrate. Maybe its a similar product.

Potato Potatoe 😊

Rectorseal 68732 36 Steamaster Tablets https://a.co/d/ftusp89

Potato and potatoes....
"Potatoe" isn't a word my friend.

AdmiralYoda

@reggi Interesting! Not sure if the formula is different than Steam Master but looks pretty good. Sodium Nitrate, Sodium Triphosphate and Sodium Metasilicate.

It says to add six tablets for every 100sq.ft. of radiation to clean/flush the boiler. Then add 4 tablets for every 100 sq.ft. radiation. Seems like alot!

@ron Thank you for that filter link! What effect would a filter like the one you mentioned have on water quality for the boiler?
https://aquapurefilters.com/store/product/200930.200952/aqua-pure-ap917hd-s-replacement-cartridge.html

vhauk

I only ever said something to point out that corrosion is more than ph. 

reggi

ChrisJ 

Potato and potatoes.... "Potatoe" isn't a word my friend.

https://en.uncyclopedia.co/wiki/Potatoe

Maybe.. maybe not 

ChrisJ

reggi said:

ChrisJ 

reggi said:

Potato and potatoes....
"Potatoe" isn't a word my friend.

https://en.uncyclopedia.co/wiki/Potatoe

Maybe.. maybe not 

ethicalpaul

> Steam mains don’t corrode because steam replaces any air which contains the oxygen.

Maybe in a steam plant, but in my house there is air in the steam pipes for 7 months every year and for hours every day even in the dead of winter. Still they are 100 years old.

Don't worry, this is a friendly discussion and I value your input!

What you said about the most corrosion happening where water and air meet is known to many steam boiler owners! I'm looking at you, Hartford Loop!!

ChrisJ

ethicalpaul said:

> Steam mains don’t corrode because steam replaces any air which contains the oxygen.

Maybe in a steam plant, but in my house there is air in the steam pipes for 7 months every year and for hours every day even in the dead of winter. Still they are 100 years old.

Don't worry, this is a friendly discussion and I value your input!

What you said about the most corrosion happening where water and air meet is known to many steam boiler owners! I'm looking at you, Hartford Loop!!

True...
But the steam mains and run outs only have distilled water in them. How does that behave?

ethicalpaul

The distilled condensate is going to be more acidic (lower ph) than most people's boiler water (especially ours who treat), but it should be quite low on oxygen. As @vhauk and I think @Jamie Hall said, it's a combination of things.

But I can't control the condensate (I'm not a steam plant), only what's in the boiler, so I do

vhauk

our pour one pipe steam system started to get pin hole leaks in the bottom of the steam mains just before the Hartford loop. Why? The installer of the last boiler reduced to 1 1/2 inch pipe which left a 1/4 inch of water in the main. 

PMJ

Jamie Hall said:

Quite true, @vhauk . However, the effect on oxygen levels in the boiler water is, while not perhaps negligible, minimal. In order to get any significant amount of oxygen into water -- something the wastewater and aquarium boys pay a lot of attention to -- takes a good deal of vigorous interchange between the air and the water. However, in a boiler, there is only a very small amount of air actually in contact with the water, and there is no appreciable circulation at all, either of the air or the water. You are completely dependent on diffusion processes, which are remarkably slow.

If it were a concern -- it isn't -- you would expect to see extensive corrosion in the steam mains themselves, where there will be air drawn in and residual water. You don't.

Now if you add water to the boiler with a decent oxygen saturation, then yes -- there will be corrosion, at least until the initial fill is boiled and the oxygen levels dropped essentially to zero. That's why it is important to find leaks, so you aren't doing that all the time.

I agree completely @Jamie Hall . It takes a lot of agitation to get oxygen into water, so once removed by boiling - especially boiling repeated several times daily, in these systems minimal amounts of oxygen will get back in and levels ongoing will be very low.

I run a bigger steam system at work with significant water makeup requirements and an oxygen scavenger is definitely required there. We monitor sulfite levels to be sure the oxygen stays below levels that would support corrosion. Oxygen pitting of the tubes can happen remarkably fast. Picture the air bubbles forming on the surface of a pot on the stove. When that is a one time or very infrequent event there is no problem in a boiler. But if oxygen is continuously being removed by boiling, meaning bubbles are always present on the heated sufaces, there will be trouble. Only raw water can supply this much oxygen. The other thing to consider is that like in the pot on the stove the oxygen forms bubbles at the places that get hot first...the same places over and over. In a tube boiler oxygen pitting failures look like someone took a drill to the tube, and a surprisingly small diameter one at that.

But at home my water add is extremely low and I add no chemicals because without significant raw water additions there is no issue with oxygen.

vhauk

Water seeks a level. Cool, we all know that. Water also seeks a balance. Water can be stable chemically, not very reactive, or it can be very reactive. For example, water that has a high ph and a low alkalinity is very reactive, extremely corrosive, not very stable. Because this combination is not in balance. Likewise water that has a very low d o will accept oxygen from atmosphere much more readily that water with a high d o. 

PMJ

vhauk said:

Water seeks a level. Cool, we all know that. Water also seeks a balance. Water can be stable chemically, not very reactive, or it can be very reactive. For example, water that has a high ph and a low alkalinity is very reactive, extremely corrosive, not very stable. Because this combination is not in balance. Likewise water that has a very low d o will accept oxygen from atmosphere much more readily that water with a high d o. 

More maybe. But the question is how much. In my experience it will not return to anything remotely close to the oxygen levels in raw water without lots of agitation. Lots of heat to remove, lots of agitation to put it back.

If this were not true then the long standing advice to bring a freshly filled boiler to steam to drive off the oxygen really wouldn't do much good if it could easily just return to the water through surface contact with still air. It really doesn't.