Oxygen corrosion causing premature failure of steam boilers

Dick Charland

Unfortunately, the biggest problem today is no one wants to monitor steam systems. In the past, we would not recommend water feeders, today they are installed regularly and no one checks water levels, add probe type LWCO's which do not need flushing and the unit will run feeding/adding water and causing premature boiler failure. The response, another piece of ---- boiler. When a steam boiler is replaced the entire system needs to be checked to make sure there are no steam leaks vents, packing on valves and returns. Additionally, if a water feeder is installed, it should be used only as an backup. Show the customer where the water should be in the glass and have them maintain that level. Explain to them that if the water goes down quickly, there is a leak that needs to be addressed. Use some method of monitoring water use, Hydrolevel has a meter on their feeder, if using a competitor, add a water meter.

Unfortunately, in typical American fashion, no one wants to take responsibility, it's someone else's problem.

Bill Anderson

Oxygen corrosion causing premature failure of steam boiler

New Steam boiler was installed 4 years ago into the heating system of 100 year old house. System has had continuous problems with vents and return line leaks. We know that a large amount of makeup water has flowed thru the system. We are about to dismantle the system and will be able to better examine the nature of the corrosion. How likely is it that the boiler would fail due to these conditions in such a short time?

Tony Conner_2

Large...

...volume of make-up water means a very short lifespan for little boilers like this. It'll be death from oxygen corrosion and/or scaling-up. Not to mention big fuel bills.

clammy

fresh water corrision

Replaced one last year and she was taking on plenty of fresh water she only lasted 4 years so it does not take long .If need be replace your wet returns it may cost you $ but in the long run it's cheaper then replacing your your boiler ever 4 to 5 years and you may save some coin on your fuel bill to peace clammy

Tony Conner

It's A Lot of $ In Fuel

If you assume the condensate comes back to the boiler at 182*F, that means there are 150 BTU/lb in that water. Cold make-up water, for example at 52*F will only have 20 BTU/lb. With the hot condensate coming back to the boiler, it's got a 130 BTU/lb of water running start to turn it back into steam. If you assume that boiler is 80% eff (proper boiler eff) then the fuel saving is 162.5 BTU/lb. That means that that amount of fuel doesn't have to be purchased & burned for every lb of hot condensate that comes back, as compared to having to use cold make-up.

Get the condensate back - it's got a lot of heat in it. And it's not full of dissolved oxygen and hardness.

Tony Conner_2

I Wouldn't...

... say that probe-type LWCOs "do not need flushing". Gauge glass and LWCOs should be proved functional by blowing them down regularly. There's not normally any flow in the connections between these components and the boiler. Those relatively small connections tend to plug up with crud. I've seen people drain things like boilers/vessels/tanks, and while they were very definitely empty (the manholes were open, and people were inside them), the gauge glass still showed half-full. The connections were plugged solid.

Unknown

Some background info

This was the 1st steam job I worked on for my present company . In 1996 we replaced the 2 back sections of a Weil Mclain 6 section 72 series ( I think that is the series number ) .

In 2001 we were back replacing the whole boiler . We had reps from Weil there to look it over and they sized the new one to the connected load , which was a 4 section of the same series . At that time we also added a water meter on the boiler feed . At the present time , there's another gaping hole in the back section . Water meter reads 1500 gallons after 4 years of use ( just for heat , not hot water ) .

1500 gallons sounds like alot of makeup water for 4 years on this size boiler . How do you figure the parameters for normal makeup water on a steam boiler ?