Advanced Piping Failure
How Corrosion Does Not Recognize The Demand For Nor The Political Correctness of Going “Green”
A new 350,000 square foot L.E.E.D certified high tech office building is designed and constructed incorporating the latest “Green” technologies. It is specifically marketed to tenants of the computer industry. A major component of its HVAC design is a popular and well known non-chemical water treatment device which is advertised to work based upon imparting a magnetic residence to the water.
The building has a large central condenser water system serving three individual package air conditioning units on each floor as well as multiple computer room air conditioning units. The building has never had traditional chemical treatment corrosion control, and has only been operated with the non-chemical electronic / magnetic device installed.
After approximately 1 year of 24 / 7 operation, the engineering department finds elevated levels of iron oxide rust in its cooling tower pans and strainers. Opening of the refrigeration heads after the 1st year of operation shows unusually high pitting to the water box and tube sheet, to further suggesting a corrosion problem. The chief engineer for the building contacts CorrView International, LLC to gain some further insight to the effectiveness of this specific non-chemical device, and expresses his doubts to the manufacturer’s claims to near total corrosion, scale, and microbiological control.
Although rust is unquestionably present within the piping system, they have corrosion coupon test results all showing a low wall loss of under 1 MPY.
A request is made to submit a proposal to ultrasonically inspect their condenser water piping system.
Approval is quickly made to the proposal and a date set for the survey. Soon after, the investigation is cancelled by upper level building management. Although the chief engineer suspects problems, the management team feels that the device is working extremely well as guaranteed by the manufacturer, and that no corrosion problems exist.
Approximately 6 months later, a large real estate interest and long time client hires CorrView International, LLC to perform a due diligence piping survey at an out of state proposed building acquisition. Although the property is very new and no corrosion problems have been revealed or disclosed during their own engineering review, our client has no experience with the non-chemical corrosion control system they have encountered during a prior walk through of the building.
Only upon arriving at the property to perform the inspection do we realize that this is the same office building which had contacted CorrView International about their suspected corrosion issue months before. Building personnel are the same, but now in the presence of a potentially new owner and property management team, they acknowledge no prior contact with CorrView International.
A preliminary discussion with building engineering personnel relates no operating or corrosion problems. All building staff provide very favorable comments regarding the non-chemical device, and state that it has met or exceeded their expectations.
Initial testing of the system shows far lower wall thickness than expected for 12 in. schedule 40 pipe. With an ASTM starting wall thickness of 0.406 in., initial exploration shows measurements of near 0.355 in., and individual examples of deep pitting to approximately 0.075 in. below factory specifications. Some high thickness measurements near 0.400 in. show that the pipe was not undersized.
Ultrasonic testing is performed throughout the pump room, cooling tower area, computer rooms, and at all distribution run-out piping to the individual units where we identify similar results in all areas. Rough calculations produce an average corrosion rate of near 30 mils per year (MPY), and areas of deep pitting which exceed 75 MPY.
Smaller 3 in. run-out piping at the units is all threaded schedule 40, and show a current wall thickness below minimum acceptable limits. Photographs are taken at multiple examples of threaded pipe where leaks are present. Two emergency repair clamps at 3 in. distribution pipe are found and documented with photographs. Such failures provide unquestionable proof that the 0.111 in. threaded thickness of schedule 40 pipe ( 0.216 in. minus the thread cut of 0.105 in.) has been compromised in under 18 months. This loss of 0.111 in. translates into a corrosion rate of 83 MPY!
The wall thickness information is presented to our client purchasing the property that same day. Although prior to our formal final report, the client decides the damage to the condenser water system would require too many resources to correct, if even possible, and that it would place them at too great a risk given the high tech tenants currently under lease.
The decision is made to back out of the sale, and no reduction in the price of the property is offered to accommodate the findings made by CorrView International, LLC.
Packing up our equipment at the end of the day we express to the building personnel thanks and appreciation for their help and cooperation to out testing effort. We vaguely express that we have uncovered certain concerns to the condition of the condenser water piping and ask what their favorable impression of the non-chemical device is based upon.
One maintenance mechanic states that they do not have to move heavy drums of chemical to the roof.
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