Increasing Levels Of Threat
How Curiosity And Due Diligence Can Re-Direct An Ultrasonic Investigation Into Entirely New Areas
Concerns to the condition of their condenser water piping system prompt an ultrasonic investigation at an assisted living home. Facility management reports abnormally high rust deposits in the strainers and cooling tower pans, and is concerned to the condition of relatively new pipe of only 8-9 years old. Although corrosion coupons are reporting low corrosion rates, visual evidence suggests otherwise.
Our ultrasonic testing identifies higher than normal corrosion activity and deep pitting in some areas. Pipe wall thickness is still acceptable even though it has suffered a large loss. We question the maintenance of the chemical water treatment program and find that the original provider failed to chemically cleanout the pipe and provide treatment for the first 4-6 months – an issue commonly identified as the starting point of most severe corrosion problems. Although a new water treatment company has taken over and is far more consciencous, we learn that that they never chemically cleaned the condenser water system of the original rust product – a deficiency which would have prevented effective chemical corrosion control and allowed higher pitting.
With this new knowledge we recommend performing some exploratory testing at the closed chill water piping given that a similar deficiency in water treatment likely existed for both systems. Ultrasonic testing immediately identifies extermely low but uniform wall thickness in contrast to the schedule 40 piping specified for installation. Following our investigation of various sections of chill water pipe throughout the facility, we find only low but uniform wall thickness which correlates to the installation of thin wall schedule 10 pipe. For their 8 in. chill water mains expected to have a schedule 40 wall thickness of 0.322 in., we measure wall thickness values of near 0.175 in. and just below the 0.188 in. ASTM specification for new schedule 10 pipe.
Irrefutable proof is gained to show that the contractor substituted thinner pipe into the chill water system, which now dramatically increases the need to maintain low corrosion rates to their minimum possible limit. We report to the facility manager that a suspicion of one piping problem has revealed two.
As the investigation continues to define the condition of now the condenser water and chill water systems, we notice new pipe installed at the fire sprinkler system. Multiple sections of new black pipe are observed intermixed with the original red painted fire sprinkler pipe – obvious evidence of a prior piping failure. Questions to the engineering department reveal that the facility is experiencing frequent leaks at their dry fire system which serve the attic area and top resident floor. Although all other fire sprinkler piping covering the lower floors is wet, the attic level pipe is dry due to the winter freezing threat. The top floor of the facility is fed downward from this attic space – thereby requiring a dry system as well.
As we have documented extensively in past investigations, we express to the engineering department that dry fire systems are “dry” in name only, and leave sufficient water behind during each test cycle to greatly accelerate corrosion activity. Water typically remains at the lower 1/3 or more of the pipe, covered by abundant air and oxygen which then generates extensive rust deposits. A pipe failure at a dry fire system, therefore, rates far greater concern than just to the repair costs, water damage, and inconvenience to the facility, and has the potential to render the entire fire line totally inoperable.
Spot testing near the dry valve produces a severe wall loss easily explaining prior failures. In discussion with the maintenance personnel, we find that failures have also occurred within the attic space, but that they have no knowledge to the interior conditions of the pipe which failed due to their having been removed by different fire protection contractors. Multiple examples of attic pipe have been replaced over time, but no concern to its condition or potential threat from internal deposits has been conveyed to anyone at the facility. Increasing the level of threat to the facility, we further learn that the top floor protected by the dry fire system is for assisted living tenants having fully functioning kitchens with stoves.
We contact the facility manager and express our very serious concern to this situation. Although our original focus was to the condition of the condenser water piping, we impress upon the manager that corrosion at a fire sprinkler system carries far greater potential consequences and should be addressed at this time. With only one day of field testing budgeted, we express far greater concern to the condition of the attic fire sprinkler pipe, and suggest it would be to the interest of the facility to abandon further investigation of the condenser water and chill water systems to focus instead at this new issue. We also offer to spend a few additional hours on site at no additional charge.
Testing identifies thin wall schedule 10 fire pipe as would be expected today for an wet or dry fire sprinkler system. Black ASTM A135 carbon steel pipe is installed. Ultrasonic testing immediately identifies very severe wall loss and low measurements representing more than a 60% wall loss along the bottom half of the pipe. Beginning at the main 5 in. supply line, we measure extremely low wall thickness well below minimum acceptable standards. A far greater concern is raised to the volume of iron oxide rust products which are likely trapped within this piping system. With the greatest wall loss at the beginning of the supply line due to a greater movement of fresh water, we can anticipate that any downstream fire sprinkler head calling for water would likely receive instead some portion of the lose rust carried from all the fire pipe before it.
We raise a significant concern to the property manager that should a fire exist at the top floor of this nursing home, the rust in the pipe may prevent functioning of the fire sprinkler heads. The very high deterioration of the main 5 in. and 4 in. pipe strongly suggests that a fire covered by any downstream piping would likely not receive any water through the sprinkler heads. Complete replacement of both dry fire systems covering the attic space and below 4th floor tenant space is required as soon as possible. We recommend bringing mobile firefighting capability to the 4th floor while the replacement of the dry fire sprikler systems are planned and executed. We also recommend removing specific examples of pipe to confirm the volume of internal rust deposits which we suspect exist.
A far more limited report is provided to the facility covering the condenser water system due to re-direction of our investigative resources to the chill water and fire sprinkler systems, but provides enough evidence to plan changes and reduce the corrosion activity. Recommendations are made to install side stream bag filtration to the chill water system and to greatly elevate corrosion inhibitor levels.
More than six months later we are contacted by the fire contractor who replaced the fire system and are informed that when the 5 in. pipe was opened for visual inspection, it was almost entirely clogged with rust and thick mud. The overwhelming consensus in following- up our recommendation to visually inspect certain areas of attic area pipe in confirmation to our ultrasonic findings is that the fire sprinkler system had zero possibility of functioning during a true fire emergency. All those involved with the visual inspection of the fire system express their deepest gratitude for CorrView having the experience to recognize such a severe problem which had been overlooked by everyone else.
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