Extreme Corrosion issue well water

[orcas]

Hello...have been looking for assistance on solving what is becoming a very expensive boiler issue and have had no success with the local experts here in San Luis Obispo, CA. We have replaced 3 boilers in the last 6 years (at a cost of $8,000 each). We are being told that the corrosive quality of the water is the issue corroding the SS heat exchanger...so we had a new water system put in and just had a water analysis done. Among other things of concern we have a ph of 12. I would VERY much appreciate assistance in reading the water report and I can email it but can't get it to paste here but have uploaded (pdf file). We currently have no hot water as we cannot put in another boiler until we have a solution to the water so there is some urgency to this request. Any assistance or direction for assistance is greatly appreciated.

Thank you.

http://files.engineering.com/getfil...efdc1d&file=Aug_2010_water_test_Lone_Palm.pdf

 

[bimr]

The water analysis is quite unusual in that you have over 300 mg/l hydroxide as reflected by the pH of 12.

This water would generally not be corrosive to stainless steel. However, because of the high level of chloride, you may seem some stress cracking corrosion.

The water will be extremely scaling as reflected by the water hardness. The hardness is extremely high. If you ran this water through any type of heat exchanger, the water will thoroughly scale the heat exchanger in a very short time.

You need to install Reverse Osmosis (RO) water treatment equipment or connect to a municipal water supply.

The RO equipment is capable of removing 90+% of the water parameters in your water analysis.

Please describe the water treatment system that you have installed. It must not be working.

 

[orcas]

We took over this project/property 4 months ago so it seems that the corrosion has been on going...since we got it we have done the following: Starting at the well water...we have a 20 micron filter then a 5 micron carbon filter. That water is brought into the house then Y'd off. One side goes directly to the boiler without further filtration (the boilers that have had the corrosion issues). The other Y goes: through a Water softener then another 5 micron carbon filter then UV Trogan max system. In addition on ONLY the kitchen sink we have a RO system. We have spent tens of thousands of dollars on this 'all' new system so if you have any ideas on adding something less costly than an entire house RO it would be appreciated. In addition, water is at a premium here and an RO system (as I understand it) can waste quite a bit of it. Your thoughts and assistance are GREATLY appreciated. Andre

 

[orcas]

I should have added that the boiler companies will not warranty systems with distilled water running through them...I don't know if an RO system would void the warranty but if it takes out all minerals my understanding is that it would...

 

[bimr]

This water will be more of a scaling problem than a corrosion problem.

As a minimum treatment for the heating equipment, you should treat this water with a water softener to remove the hardness. The hardness present in the raw water will ruin the heat exchanger equipment.

The hardness of the water is so extremely elevated, that use of a water softener may be very expensive. However, use of the water softener will be less expensive than buying soap (hard water requires additional soap) and replacing scaled up heating equipment.

The existing pH of 12 is outside the drinking water range. You will also have to feed some type of NSF approved acid to reduce the pH to the 8-9 range.

There will be a long term issue with stainless steel stress cracking corrosion because of the elevated chloride content. You will have to use an RO process if you desire to reduce the chloride.

This water is not going to be aesthetically pleasing for drinking water purposes. If you want high quality potable water, then you will have to use RO. And yes, the RO will waste 15-25% of the raw water.

Another option that you should investigate is the drilling of new water well into a different aquifer.

Regarding “should have added that the boiler companies will not warranty systems with distilled water running through them" ....That is an incorrect statement. For example, all modern utility boilers run on ultrapure distilled water.

Yes, distilled water may be slightly more corrosive than regular tap water, but distilled water may be easily treated to remedy the corrosiveness.

The micron filter is not doing anything for you since the turbidity is already low. Micron filters are used for turbidity removal.

The UV is also probably not doing anything for you either. The UV treatment is for disinfection.

 

[orcas]

Thank you very much...can you direct me to someone who can advise on the treatment system? Central Coast California..I know Culligan does our house water softener but don't know if they are suited for this..

I'm wondering if I should put an RO on just the line coming to the boiler (we already have one on the drinking water) - that way it would be a reduced cost and would use much less water than whole house? If I do use RO on the boiler would I still have to deal with the ph level and TDS issues for the boiler?

Again your help is MUCH appreciated.

Andre

 

[bimr]

The technical asistance will be only as good as the person working on your project.

Do any of you neighbors have wells? They would probably be able to reommend a water treatment supplier. You can also ask your local well driller for a referral. Culligan also does these types of treatment systems.

You definitely should use RO on the boiler feed. The discharge pH on the RO will be much lower than the raw water. You may be able to blend 10% or so of the raw water with the RO treated water. Blending raw and RO treated water will help to control the pH.

 

[orcas]

New twist. I'd love your opinion as it seems you are the most knowledgable of anyone I have spoken to....So I brought out a 'water expert' today and he found something disconcerting. The water PH from the softened (house) and hard (boiler) water are all 7.1-7.4 NOT 12 ph. We then retested at the storage tanks..7.2...and from the well 6.8. There is nothing but pvc between the well head and the storage tanks...in any case no 12PH water was to be found which now makes me suspect on that aspect of the water analysis. The 'water expert' also recommended just softening the water to remove the calcium and magnesium to the boiler line to prevent build up. He saw nothing else that he was concerned with. I don't understand the high Choloride of 740 though. I'm not sure if that is a concern if we soften it and the ph is actually at 7.1 to 7.3.

Any further advice?

Many thanks...andre

 

[bimr]

I started out by saying that the water analysis is quite unusual in that you have over 300 mg/l hydroxide as reflected by the pH of 12.

I have no explanation as to why the water would have these parameters. Is it possible that the sample may have been contaminated with bleach or a household cleaner?

I would have the lab retest the water. The lab will probably do it for free if you point out to the lab that the hydroxide concentration is so unusual that it has to be a mistake.

Regarding the softening, if you remove all of the hardness, the water will be somewhat corrosive, especially if the TDS is high. I would not expect that the stainless steel boiler is going to effected by zero hardness water, but your plumbing faucets or other metal components will be subjected to the corrosion.

To reduce the corrosion of completely softened water, you can either:

1. Raise the pH slightly; or
2. Blend some of the raw water so you have some hardness in the blended water. Maximum hardness of blended water should be less than 120.

However, before you do anything further, I would have the water retested.

 

[orcas]

Thank you. Again...seems like the best advise. We will contact the testing company and have them retest.

Andre

 

[sir67]

I NEED A ADVICES
I have a porblem with high chloride in boiler after every 4 ot 5 week i do blow down to control chloride level.
i do not understand why it happened?
Water quality is very good pretreament systems are consist of softner, carbon filter, mix bed and demin.
so there is not indication to increase chloride in feed water.
Ammonia is used for ph control and ammonia contain less than 1 ppm chloride and we diluted it. no other treatment.

Any one can tell me what are other sources of Chloride.

 

[bimr]

Don't know what type of plant that you have. Do you have condensate returns?

Is it possible that you have a oondensate leak of some type? I would not expect chloride to be passing through your makeup system.

 

[sir67]

Thank bimr

Coal fire power plant with water cooled system.
yes have condensate retures.

If condensate leak some time? why chloride is always higher ? on the other hand sulfate and sodium always with in limits.

level of chloride is always higher after 5 to 6 weeks so i do the blow down to control chloride.

 

[bimr]

Would suspect you have a condenser leak of some sort. The cooling water probably has a higher chloride content.

Do you have a condensate polisher?

 

[sir67]

yes i have condensate polisher.