Following The Wrong Path – Again And Again
How Facts and Common Sense Do Not Always Lead to the Correct Actions
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.
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.
To 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.
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.
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.
The Leading Cause Of Pipe Failure At Condenser Water Systems
Despite various corrective measure, advanced failures at condenser water systems are on the rise. Many problems are engineered into the system from the start due to the failure to recognize the impact rust deposits and particulates have on producing higher secondary corrosion levels. In addition, most corrective measure, if they are attempted, fail to provide a solution. Here is why.
Undersized Steel Pipe
A Simple Dial Caliper Measurement Of New Steel Pipe May Reveal Surprising Results
In addition to the many corrosion influences negatively impacting piping systems, many new building properties are constructed using carbon steel pipe which is below factory specification. To the surprise of many, an FM or UL approval, like its ASTM stamp, does not define that the pipe actually meets ASTM thickness standards.
The Decline In The Quality Of Today’s Piping Products Means Greater Corrosion Problems
A large number of negative influences have comined to produce a higher frequency of corrosion problems – often in spite of all precautionary measures taken. Of those, lower quality pipe, undersized pipe, more complex piping layouts, and generally less effective chemical treatment options have produced a “Perfect Storm” contributing to more piping failures.
When Pipe Corrosion At A Fire Protection System Can Cost Lives
The time to learn of a fire pipe corrosion problem is not during an actual fire emergency. Internal rust deposits can, and have, totally blocked water flow through the sprinkler heads – resulting in the loss of human life. More common at dry systems, internal deposits are a serious threat to all fire protection systems.
Fire System Failures
Major Misconceptions Within The Fire Protection Industry
Ignoring the obvious does have serious consequences when it comes to fire protection systems. From the use of thin wall schedule 10 & 7 pipe, to lower quality pipe products, to frequent flow testing which brings in new fresh water, clear and well documented reasons exist to explain the higher corrosion activity found at today’s fire protection systems.
Fire System Corrosion
The Threat Of A High Corrosion Condition To A Fire Sprinkler Line
Often viewed only in terms of water damage in the case of a corrosion induced pipe failure, far more serious concerns exist, although rarely considered. Unlike HVAC piping systems, corrosion activity at fire related piping can impede and in some cases totally block water flow – a potentially life threatening condition during any fire emergency
The Benefits of Ultrasonic Testing in Determining Corrosion Rate and Service Life
Ultrasonic testing provides the most comprehensive, accurate, and cost-effective tool to assess the condition and remaining service life of any piping system. Planned and performed properly, ultrasound offers the first step toward identifying a potential corrosion problem, or for certifying a piping system as fit for service.
Why Not All Pipe Failures Are The Fault Of Your Chemical Water Treatment Provider
Various design elements to any piping system can have dramatic impact upon its corrosion activity. Pipe origin, schedule used, physical layout, and many other unknown factors can produce a pipe failure. And yet they are completely beyond the realm of protection offered by chemical water treatment.
Corrosion By Design
Pipe Corrosion Problems No Water Treatment Program Can Protect Against
Various changes have occurred to mechanical piping designs over the past few decades, with virtually all HVAC, plumbing, and fire protection systems having been affected in some way. Many changes relate to the materials themselves. Major changes in piping design, however, have introduced new corrosion problems no chemical treatment program can stop.
The Benefits and Limitations of Corrosion Coupons
Relied upon for decades as an indicator of corrosion activity within piping systems, corrosion coupons are highly unreliable in most examples, and totally worthless in others. Many of the most damaging corrosion failures have occurred while at the same time corrosion coupons produced excellent results. Here is why.
If Corrosion Activity Is Only 0.4 MPY, What Is Wrong With The Above Picture?
Corrosion coupons reported a 0.4 MPY corrosion rate for 6 years where the actual rate exceeded 25 MPY. Believed implicitly in contrast to multiple leaks and failures, the slow but total destruction of the entire condenser water piping system was the net result. A case history illustrating the threat from relying exclusively upon this highly flawed testing method.
Dry Fire Sprinkler
Fire Protection Contractor – Antifreeze: The Fine Line Between Hero and Defendant
Antifreeze used in dry fire sprinkler systems may solve one problem, but has also proven deadly. Rated a Class 1 flammable liquid, antifreeze can accelerate a fire, create a fireball, and even cause an explosion. Although now restricted to lower concentrations, antifreeze still adds heat value to any fire and introduces new and unknown liability to any such system.
American Welding Society – Understanding Pipe Corrosion Problems
A piping system that satisfies service life demands, requires the recognition of piping design vulnerabilities, effective corrosion monitoring, and the adoption of corrective measurements. With corrosion related failures on the rise, and with generally lower quality pipe being installed, advanced planning and an awareness of potential threats becomes more important.
World Pipelines – Investigation vs. Procedure
Substantially different findings are likely where ultrasonic pipe testing is approached as a forensic investigation based upon known system problems and vulnerabilities, rather than simply a linear based measurement procedure. A critical importance is understanding the inherent corrosion related problems to various piping systems. An adapting investigation will also produce a more definitive answer to any piping problem.
Fire Pipe Corrosion
Fire Protection Contractor – When Pipe Corrosion In a Fire Protection System Can Cost Lives
The time to first learn of a pipe corrosion problem is not during a true fire emergency when lives are in jeopardy. Thinner pipe, more corrosive steel, lower quality galvanizing, foreign pipe, dry systems, MIC – all such negative factors are driving toward higher internal corrosion deposits to render your fire protection system worthless.
Fluid Handling Systems – Finding The Remaining Service Life
Ultrasonic testing is, by far, the most informative diagnostic method available for determining pipe status, as well as extremely cost effective. An effective piping analysis is much more than a spreadsheet of a few wall thickness measurements – requiring careful statistical analysis and practical interpretation of the data.
World Pipelines – Multiple Metering And Monitoring Needs
With no single form of corrosion monitoring capable of proving full coverage to the many different forms of pipe corrosion possible, multiple testing methods are always advised. These should include ultrasonic testing, spool pieces, LPR, regular internal inspection, and a close observance to the often obvious but missed signs of a problem.
A 30+ Year Knowledge Base
Unfortunately, the above is a very common progression of events for many of our clients. Often, greater attention to chemical corrosion control and corrosion monitoring could have saved the system and avoided the problem. In others, a decades prior design flaw or poor choice of pipe supplier may be traced back as the primary fault.
During the 20 years that we have been involved in the field of ultrasonic pipe testing / corrosion monitoring, we have authored various Technical Bulletins for the benefit of our clients. These Technical Bulletins address frequent problem issues to any building owner or operator, and offer both insight as well as reasonable and proven solutions.
We offer below the various categories available, and continue to add new bulletins as time permits.
Interior Rust Deposits, Common Threats, Corrosion Types, Winter Lay-Up, MIC, Corrosion Monitoring and Testing, CUI, Corrosion Coupon Failures, Rust Removal, Reducing Corrosion Threats, Roof Level Corrosion, Drained Pipe, Corrosion Trends, Fire Sprinkler Corrosion, Corrosion At “Free Cooling” Systems
The Impact Of Flow Rate To Higher Corrosion, Inadequate Water Filtration, Piping Layout Design, “Green” Piping Designs
Corrosion Threats, Design Misconceptions, Interior Rust Deposit Threat, Dry Fire System Corrosion, Schedule 10 Pipe, Premature Failures, Clogged Fire Systems, Chemical Control Options, Remediation Choices
Condition Assessment, Due Diligence, Preparation Prior To Renovation, System Evaluation, Expert Witness
Heat Exchangers, Benefits of UT Testing, High Pressure Water Jet Cleaning, Filtration Errors, Chemical Treatment, Condenser Tube Coating, Mold Concerns, Chromate Removal, Growing Threat of Corrosion, Heat Exchanger Tub Coating, Nondestructive Testing
Schedule 40 Limitations, Piping Trends, Hidden Corrosion Threats, Dielectric Insulators, Clamped Grooved Piping, Piping Schedules, Pipe Testing Specification, Roof Pipe Draining, Low Corrosion Guidelines, Dual Temperature Piping Failure
Cold Water Threats, External Corrosion Issues, Fire Reserve Tanks, Interior Pitting, Protective Coatings, Rehabilitation
Improving Heat Transfer Efficiency, Improving Filtering Efficiency, Filter Placement, Poor Performance Causes, Filter Selection Considerations
Chemical Treatment Challenges, Limitations to Water Treatment, Corrosion Coupon Reliance