Steam question (pH question)

Steamhead

try flushing and skimming the boilers if you haven't already. I'll bet there's some oil and dirt in there. If that's not the problem, in "Lost Art" Dan says a pH below 7 is not good for the pipes.

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David Van Wickler_3

Proper pH for low pressure (5psi)

I am looking at a problem with a surging waterline - The boilers are vertical steel firetube and have 75 gallon of water with 900MbtuH input dual fuel power burners. The manufacture says surging is not caused by the boiler design.

What is the proper pH for a low pressure system?
Is underfiring the boiler ok as long as the system pressure is sufficient?

Blackoakbob

boiler ph....

Just for starters, you should be using soft water as makeup and try to get to O (sero) hardness, use some Ph
test papers to check and stay above 7.0 (too acidic and it will attack the boiler and the piping), use some good quality boiler treatment and test frequently...boiler water treatment is an ongoing process it is never done. You soften the water, test and treat the water and if that doesn't work you "throw it away" ( blow down and skimming)
Carryover of water with steam can cause waterhammer and loss of heat from the steam to the condensate thereby loss of efficiency. Hope this helps.
Best regards,

Ken_8

The SBI,

Steel Boiler Institute, suggests a pH of 10 will stop all corrosion.

For starters on all our large boilers we flush them with TSP rather than skim. Most steel tube scotch marine type boilers do NOT have a properly located skim tapping and even if they did, the time it would take to get all the oils and junk off the surface of the water even with a 2 or 3" tapping would take days - not hours.

We add about 1 pound of TSP per 10 H.P. for moderately dirty boilers and double that for dirty boilers (which yours sounds more like). Run the boiler to almost steaming but NOT ACTUALLY STEAMING and allow it to sit for 4 hours. Then refire the boiler again until near steam, BUT NOT ACTUALLY STEAMING, and dump the soapy, filthy water from the lowest blow down and drain as fast as possible.

Rinse with clean water, drain that from only the bottom drain, and refill with clean water.

Trace amounts of TSP will raise the pH slightly - which is a GOOD thing.

Water treatment is a must with large boilers like this. Have the water tested and use chemicals that will protect the boiler. If the system has leaks, fix 'em before doing any of this. Leaks are the #1 cause of the problem you have. It demands tons of make-up water that has all the stuff in it that boilers are killed by: oxygen, calcium carbononate, chlorine, and flouride - just to name a few.

Let us know how you make out.

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David Van Wickler_3

pH

Thanks a bunch - going to the job tomorrow with the installer.

So here is a bunch of other stuff I've found out by asking.

The orginal system had two large tanks - it appears there was a surge tank and the boiler feed tank. It seems that the engineer didn't need two tanks, only the boiler feed tank. So when the system cold starts the boiler feed tank runs dry. Well, they also have a problem with live steam in the condensate reciever tanks so the trapped the lines prior to dumping into the receiver (Yup double trapping).

So when the (7) 900MbtuH boiler fire the feed tank water level drops, the feeder valve opens wide to make-up and then Whooooosh, here comes the condensate back the the feed tank, and phfoooosh goes the condensate out the vent as the feed tank overflows by about 200-250 gallons.

So we're dumping chemical, bringing in fresh water and now there's a problem with surging water lines.

Oh yeah. The problem isn't so great when they are fired on Nat Gas. Why? Because they have to underfire the burners since the venting is not optimal and there was insuficcient draft. And on Oil the surging is enough to trip the low water cut-off on the boiler.

Also - I'll find out if there is an equalizer line on each boiler. What happens if there's no equalizer line on the boiler?

- Fun Fun Fun.....

Thanks to all - DVW