Weil Mc-Lane Steam Boilers Rotting Out

[kpdualie]

anyone else experience severe corrosion of Weil-McLane series 80 steam boilers. I just replaced my second boiler in seven (7) years; the first series 80 lasted less than three (3) heating seasons before several of the sections rotted out at the top. I was supposed to get some credit from WM for a new boiler so I installed another WM series 80 and that one also rotted out after four (4) heating seasons. WM refuses to warranty or credit for their defective boilers; saying instead that there MUST be a leak in the system and the only way that these boilers could rot out so quickly is due to a large amount of make-up going into the boiler. four years ago, after the second WM boiler was installed I inspected all of the return lines in the building and found NOT one leak and then turned off the auto feed to see if I was losing any water. After four days the water level hadn't changed (yes, this was during the heating season and we were pushing steam). WM's response is that since I didn't have a water meter on the feed line there is no way to prove that the boiler wan't using a lot of make-up and therefore they won't warranty. after two bad boilers I obviously decided to look elsewhere. I manage another building in the same neighborhood using the same hard water and the same size boiler, not WM, and that boiler has lasted over 20 years. I seem to recall that WM said they had some design issues 7-8 years ago and that they were supposedly resolved in the boiler I bought from them four years ago; obviously not. the sections of the boiler I just replaced literally fall apart when touched.

 

[pmover]

for others to understand, i gather these WM boilers are cast-iron sectionals.
when boiler metal is corroded, one needs to think about the cause of corrosion. often, the cause is poor water quality. however, since you seem convinced it is WM design and not a water quality issue. i would be certain by having a flow-meter measure the make-up water. excessive & poor make-up water quality may very well be a problem. is the boiler water and/or condensate monitored/treated? monitoring boiler/condensate quality would be beneficial to determining the source of corrosion.
have you considered problems associated with dis-similar metals? chances are that this would be a localized problem.
also, taking a sample of the boiler metal and having it analyzed may also be beneficial for you to determine cause of corrosion. take several samples and have 2-3 labs conduct the analysis.

Good Luck!
-pmover

 

[chicopee]

I am assuming that there is no process heating taking place and that the heating radiators do not let steam blow out. So can you be more specific about the word "Rot"? Also where was the "Rot"? On the fireside? water leg nipple connections? piping connection?
About your water quality? Have you checked for chorides? Has scale build up on the sections? Do you drain the mudd legs periodically to check for sludge build up?

 

[kpdualie]

the boiler is used in an apartment building and aside from the hot water coil used for domestic hot water there is no heat process. the mud leg is drained on a regular basis as is the low water cut-off. we have checked all of the air valves on radiators and risers repeatedly and change them as needed, as far as I know we don't have any that are blowing steam constantly. as already mentioned we have inspected every return line and have not found any leaks. the location is new york city and I know the water is very hard and recent testing confirmed that; I plan to institute a chemical treatment system for the make-up. but for 25 years I have never had this type of boiler failure in any building in Manhattan. both of the WM boilers that rotted out were cast iron steam sectional and they rotted out at the top of the sections. I'm not talking about a few pinholes in the most recent failure; I could put my fist through the hole in one section. another observation is that in December of 2007 this boiler was cleaned and the mechanic pointed out to me that there was evidence of a problem in the sections that failed but at that time there was no leakage. I contacted WM to schedule an inspection at that time but they were non-responsive. we were making steam for heat from 12/07 until 5/08. from 5/08 until 10/08 we did not make steam and only used the boiler to make hot water until I reinspected the boiler in Oct of 2008 and found that the corrosion/rot had advanced to the point of failure. WM's position is that a large amount of make-up had to have been introduced into boiler. I didn't have a meter on the feed at that time but I am having one installed on the replacement boiler. I did save two of the rotten/corroded sections if anyone is interested.

 

[moosesp]

A chemcial treatment program for water make-up is definetly bennificial. I would suspect that the chemical treatment program that the city is using for there domestic water has changed since you have not had these problems in the past. A high amount of oxygen present may be the cause of the corrosion and subsequent failure of the boiler in the steam portion of the boiler. A ballanced chemical treatment program will include a phosphate treatment for dissolved solid control, a soduim sulphite for an oxygen scavenger, and amines designed to protect the steam piping and condensate return lines. The boiler manufacture probably has recomendations on chemical treatment levels required to maintain your warranty. Just my two cents!

 

[chicopee]

I grew up in Westchester county and New York City from what I remember gets reservoir water from several watersheds in Westchester county. Typically water from watersheds is not hard but you may have a chloride probem due to road salting operations.