Following The Wrong Course

A Corrosion Problem Can Provide The Opportunity For Others To Benefit At Your Expense

Preface

A mechanical engineering firm is hired to design a HEPA or high efficiency particulate filter housing around their client’s roof level cooling tower in order to clean the air.  The interest of the facility is to stop the capture of airborne dirt and debris which their client believes is interfering with process equipment served by the open condenser water system.  Three large sand filters have been installed, with the filter room being expanded to accommodate additional filtration units.

The engineering firm recognizes the difficulty of filtering the large volume of air pulled through multi-cell cooling towers serving near 2,000 tons of refrigeration, and questions the need for such unusual measures never before encountered in the HVAC field.  Subsequently, the engineering firm recommends a piping survey to determine whether corrosion may be responsible for any of the debris causing the operation problems to the facility.  An Internet search leads to CorrView International, who are brought into the project

Investigation

Testing immediately identifies severe corrosion activity exceeding 25 mils per year (MPY).  Our finding of very deep pitting to near 0.075 in. suggests that tuberculation and high under deposit corrosion exists.  Results clearly suggest that a high corrosion condition and not atmospheric dirt and dust captured by the cooling tower is responsible for the operational shutdowns.  A widespread investigation throughout the facility shows the smaller pipe of 6 in. and below so severely deteriorated that they now require replacement.  Larger pipe can likely be saved by the effective removal of the internal rust deposits followed by a more effective chemical treatment program.

A conversation with building engineering personnel shows immediate resistance; having already determined that airborne dirt is the cause of their clogged cooling lines.  Building engineers are not cooperative with the ultrasonic investigation and provide no assistance either in the form of providing ladders and  an escort through the facility, or information about their operation.  Further investigation shows that there is no chemical treatment program other than a chlorine feed and monitoring panel.  There is an incubator and supplies for identifying microbiological activity but no standard chemical test kits.

It becomes known that the facility had abandoned its chemical treatment program years prior due to what it considered too high annual expense.  Subsequently the facility was struck by Legionaires Disease resulting in some employees being hospitalized.  Lawsuits resulted.  Experts called in due to the Legionaires outbreak then recommended an automatic feed of liquid chlorine and the continued maintenance of high chlorine residuals which continued long after the problem had been removed.  With highly corrosive chlorine injected into the steel piping system and no chemical corrosion control for 2-3 years, corrosion rates skyrocket to produce the interruptions of their process equipment.

Further experts called upon recommend high efficiency sand filtration.  This reduces the turbidity of the water and is rated highly successful, although massive volumes of iron oxide rust product still remain within the system.  Following additional process interruptions due to deposits clogging the smaller diameter cooling lines, additional filtration is recommended and installed.  All three massive sand filtration units are found having their suction inlet lines tapped into the top of the pipe  – thereby almost totally eliminating any useful function.  At this top center location, only the smallest particles of lightest mass will be captured by the filtration units.  This is a bad location for a filtration take-off if one wants to clean a piping system, but an excellent location where justifying the need to purchase additional filtration units is the main interest.

A full overall assessment of the facility shows that a failure to follow standard building maintenance and chemical treatment operations in favor of salesmen driven recommendations resulted in the destruction of a major component of their piping infrastructure.  Their problem never had to do with airborne dirt as they convincingly believed, but due to the lack of proper chemical treatment.  In essence, the facility was dissolving its pipe into iron oxide by continuously feeding liquid chlorine, and then filtering some of their pipe out and flushing it down the sewer.   The various outside consultants involved seem to have been motivated primarily by furthering their own sales, rather than to solve a relatively simple problem.

Conclusion

Our final report on the subject property stops all plans to filter the air to the cooling tower, and results in major pipe replacement.  A water treatment program is installed and the chlorine feed discontinued.  CorrView International also recommends creating a closed condenser water loop to the critical production equipment through the installation of a plate and frame heat exchanger, and to maintain an effective chemical treatment program through close monitoring.

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Dead Zones

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.

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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.

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Inevitable Corrosion

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.

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Corrosion Threats

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.

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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.

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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

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Ultrasonic Testing

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.

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Corrosion Influences

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.

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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.

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Corrosion Coupons

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.

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Unexpected Failures

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.

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Corrosion Trends

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.

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Testing Procedures

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.

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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.

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Ultrasonic Testing

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.

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Pipe Corrosion

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

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Corrosion

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Failure

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Repair

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Replacement

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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.

Current Categories

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