Following The Wrong Path – Again And Again

How Facts and Common Sense Do Not Always Lead to the Correct Actions

Preface

A luxury condominium has been plagued with corrosion problems at its condenser water piping system since opening, and has received various conflicting recommendations toward resolving its corrosion issues.  They have already replaced all small threaded pipe nipples based upon an HVAC contractors suggestion that they only have a galvanic corrosion problem, but experience the same problems following that effort.  The building hires CorrView International, LLC to perform an ultrasonic investigation of the condenser water piping system, and to provide recommendations to correct the problems identified.

The building has a central open condenser water system which splits into 6 sets of small risers feeding individual A/C package units for the tenants.  All piping is schedule 40 carbon steel, and ranges from 10 in. diameter near the cooling tower and pump room to 1-1/2 in. at the A/C units.

Investigation

Our investigation identifies severe corrosion and pitting activity throughout the entire system.  Although the knowledge is not forthcoming, we ultimately learn that no water treatment has been provided to the building for approximately its first two years of operation.  A small, undersized sand filtration unit has been running since start-up, but it is installed backwards to provide no possible benefit.  Observation shows that the unit has not only been installed at a dead-end line, but that the clean filter discharge is feeding back into the filter inlet.  A new chemical treatment company has been retained and is installing new chemical feed equipment, but has not yet implemented their corrosion control program.

We identify high corrosion activity and severe pitting to near 30 MPY, and document that all pipe of below 3 in. in diameter requires replacement.  We strongly recommend against a planned chemical cleaning, which we feel cannot be safely performed until the weakness of the smaller pipe is eliminated.  We recommend an immediate review of the chemical treatment program to ensure that corrosion rates will be drastically reduced.

We very strongly recommend closing the condenser water system through the installation of a plate and frame heat exchanger and second set of pumps installed at the roof level cooling tower.  Our argument in this recommendation is that so much rust debris exists, and the pipe is already so heavily deteriorated, that only high levels of dual inhibitors and gradual chemical cleaning will solve their problem.  Once the piping system to the tenant units is closed off from the atmosphere, the  significantly higher corrosive impact from open conditions is removed, and far greater control of their problem can be achieved.  This recommendation is not even considered for a feasibility evaluation.

Approximately 1 year passes and we are again called back to this same property.  Most pipe of 3 in. and smaller size has been replaced with heavy wall Type K copper tube but new pinholes are now showing up at the heavier 4 in. carbon steel distribution lines.  Ultrasonic testing again defines very high corrosion activity near 30 MPY, and re-testing of the same areas measured earlier shows another approximately 0.030 in. loss to provide a further confirmation to our high corrosion rate estimates.  No benefit has been provided to the piping system, and lower corrosion activity has not been achieved by the new chemical treatment provider.

Subsequent to our field investigation and prior to submitting our final report, a corrosion specialist, now having been hired by the condominium manager, contacts CorrView International, LLC to discuss our findings.  The consultant advises CorrView International that there is no longer a corroson problem at the building, and that through their intervention and corrective actions, they have achieved the lowest corrosion rate ever documented at any building property in New York City.  The consultant demands a draft copy of our UT report to “review and approve” prior to our submission to the building.  This demand is ignored, as we do not submit draft reports for others to attempt to modify and alter toward their own or other interests.

As a result, the consultant advises the condominium to ignore the CorrView pipe testing report and to continue with the cleaning and treatment program they have been overseeing during the entire past year.  A new corrosion coupon rack is installed to replace the original rack, which produces the same excellent results defining exceptionally low corrosion activity.  A drum of chemical cleaner is introduced into the piping system, after which total success is declared at removing the internal rust problem.  Each corrosion coupon report confirms very low corrosion activity at below 0.5 MPY.

Another year passes and new leaks at larger 6 in. risers prompt a third ultrasonic investigation by CorrView International, LLC.  Additional areas of pipe are replaced, where internal inspection shows greater than 50% constriction of their inside diameter.  We again find extremely high corrosion and pitting activity to near 30 MPY and now show significant weakness at the 6 in. and larger main line piping and risers.  Testing shows very severe pitting now reaching minimum acceptable standards of 0.100 in. in some areas.

Recognizing the massive conflict between our ultrasonic testing results and those claimed by the building’s corrosion consultant, we perform ultrasonic testing at the 1 year old steel corrosion coupon rack itself – whereby we document very high wall loss.  At the 1 in. schedule 40 black steel pipe having an ASTM defined initial wall thickness of 0.133 in. from which the rack is constructed, ultrasonic testing measures low wall thickness values to near 0.091 in.  This translates to a 0.042 in. wall loss over a one year period or exactly 42 MPY.  Results show that corrosion at the threaded ends of the coupon rack pipe are closely approaching the outer thread cut for 1 in. steel pipe of 0.072.

articles casehistory 12To further confirm our ultrasonic measurements and in the attempt to make one final argument that we believe no one can possibly dispute, we photograph leaks occurring at various threaded pipe connections at the coupon rack itself!

While the corrosion coupons are providing a corrosion rate estimate of near 0.4 MPY, in reality, the carbon steel pipe rack itself, within which the corrosion coupons are housed, is corroding at a rate of 42 MPY.  In this example, corrosion coupons have under reported true corrosion activity by 100 times, for an error rate of over 1,000 %.

The building engineer has also collected 55 gal. drums of failed pipe which has been removed recently to show massive internal deposits.  Such deposits contradict claims that a prior chemical cleaning was totally successful, but like every other piece of evidence presented to the condo management and chemical treatment consultant, this indisputable evidence is ignored.

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The building condo management and board is convinced by the water treatment consultant that the condenser water system is fine, that corrosion activity is as low as can be achieved, and that continued dedication to the chemical cleaning and treating program will solve their problems.

Conclusion

Three years later we are advised that the remainder of the condenser water system failed, and that the entire condenser water system has been replaced.