1001-D

9A

THE "PARKER" BOILER WATER TREATMENT PROGRAM

AND REPORT ON GALVANIC CORROSION & ELECTROLYSIS

BY:  FRANK M. KOSCIELSKI, JR.

 

 

We have an increased belief in the necessity of a complete or total Boiler Water Treatment Program.  We call our Program "PARKER" and fell that our Program contains the six essential ingredients of a successful Boiler Water Treatment Program:

 

        "P"       is for Preliminary  analysis.  The accurate and thorough water analysis is the keystone to identifying the problems to be corrected by the treatment.

        "A"       is for Analytical recommendations.  Those recommendations are based on the continuing water analyses and specific job requirements to select and use the proper treatment to do the best job.

        "R"      is for Regular  uniform treatment feeding methods and regular preheating when required.

        "K"       is for Knowledgeable boiler operating and blowdown procedures.

        "E"       is for Enterprising, follow-up water analyses to verify proper treatment usage and operating procedures.

        "R"       is for Routine periodic follow-up internal inspections and to verify that proper protective films are coating the boiler tubes.

 

This complete Program can be very vulnerable if only a partial Program is instituted.  Without starting a complete analysis, someone is selling a treatment product without knowing what the treatment problems are.  While this may work out occasionally, logic dictates that a thorough analysis should be made and utilized as a tool to recommend the proper treatment and dosage.

 

Frequently, the treatment is not uniformly added in adequate dosage.  The batch treatment method of adding compound once or twice per day may result in a problem, particularly when there is low percentage of condensate return.  On systems with a high percentage or 70% or more return condensate, the treatment should be uniformly added three times or more during each 8-hour shift  with a compound feeder. 

 

Even with the proper Water Treatment Program employed, the results are not successful unless the boiler is properly blown down and correctly operated.  See our water treatment instruction bulletins 101-5, 1001-B, 1001-C for more information.  Both the follow-up water analysis and internal inspections are absolutely essential to verify the proper operating and Treatment Program.  The periodic internal inspections will verify the condition of the boiler and determine if a thin protective film or coating has developed in the boiler tubes as recommended.

Report on Galvanic Corrosion & Electrolysis

We became aware of a problem from a number of tube failures due to electrolysis caused by galvanic corrosion.  We have knowledge of numerous boiler installations that have experienced tube failures as a result of galvanic corrosion within 3 to 18 months of service.  On each of these jobs, we were not able to build up a protective coating when using the proper Water Treatment and even when using hard water.

 

Many of these boilers were individually grounded to a copper rod driven 6' or more into the ground if electrolysis was a factor.  The D.C. millivolt readings taken were found to range from 85MV to 850MV. Within a short time after the proper grounding, the recommended protective coating build-up appeared in the tubes that was not previously possible.  Normal tube life is experienced with the continuance of an active ground and proper Water Treating Program. Time to time, the grounding rod must be turned to eliminate deposits, which insulate the rod and inhibit its grounding ability.

 

Based on these experiences, the grounding is now an essential part of our Program when this problem exists.  We do not have an advance method of forecasting a possible galvanic corrosion problem.  Our procedure is to determine this from the regular internal inspection of the tubes when a protective coating cannot build up.  It is certainly a sound recommendation to drive a grounding rod and take a reading at the time of all large boiler installations or when this problem maybe expected.

 

Such a condition can be confirmed only by properly grounding the boiler in the recommended manner and from the D.C. millivolt reading.  Readings in excess of 35MV require grounding to satisfy this problem.  It is very important to continue follow-up with regular internal inspections to be certain that the condition does not recur and to also take periodic millivolt readings.

 

Since this has not been a common problem on Parker Boiler installations, our experience is limited to a very small percentage of jobs.  However, the increased number of installations found to experience this problem  required our dedicated attention for a solution deserving of our customers.

 

To further our study of this problem, we have attended the National Association of Corrosion Engineers Seminar and have held conferences with numerous consultants in the field.  The technical information on this problem relating to boiler is very limited and we have had to rely mainly on our own field tests and the experience of other specialists.  We will continue to research this problem and report our findings and recommendations.  To date, we have been very successful in the results from our grounding and will continue these recommendations until such time as we may determine a better solution from our field experience.

 

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