CT-10:   Corrosion’s Greater Impact To Chill Water Pipe Specific Causes Leading to Interior and Exterior Corrosion of Chill Water Piping Pipe corrosion represents the 2nd greatest threat to any building property next only to fire.  Different levels of threat exist for different piping systems – a roof level pinhole leak at a condenser water line representing a far lesser threat than a chill water pipe separation over high voltage electrical switchgear equipment.  Failures resulting from the corrosion of piping systems are easily capable of producing millions of dollars in equipment and water damage for most building properties, are cited at $1 million dollars of lost trading revenue per minute for a financial institution’s data center, and has caused the loss of human life where rust corrosion product itself has stopped water flow through a fire sprinkler system. Corrosion Is A Natural And Unstoppable Force Of Nature Simply stated, corrosion is the natural reversion of certain metals back into their original elements over time.  It can be slowed and greatly reduced by precautionary measures such as the addition of chemical corrosion…

CT-09:   Dual Temperature Piping Multiple Negative Factors Which Define Its Overall Greater Vulnerability Of the various piping systems subject to corrosion under insulation, CUI, dual temperature heating and cooling systems have consistently shown the greatest vulnerability.  In contrast to many other colder temperature piping systems, a combination of multiple factors exist.  Below we itemize the top 11 issues contributing to their higher failure potential:   1. First and foremost is the generally smaller diameter pipe installed at multiple risers. Existing at 4 in. and smaller, this pipe is typically threaded in its construction and therefore suffers an immediate near 50% wall loss at the thread cut. 2. The design of dual temperature piping systems is fairly typical throughout the HVAC industry and across the United States.  Almost all such systems are installed with risers at its perimeter support columns in order to feed the below window fan units – placing the pipe into a higher humidity environment.  Moisture can and will penetrate the outer building envelop to ultimately reach pipe which is poorly protected from its effects. 3. Most dual temperature piping systems are reduced reverse…

CT-08:   Localized Corrosion Issues Corrosion Trends In New York City Building Properties The corrosion of steel piping and its related components are a continuous and virtually unstoppable process.  Only fire presents a more potentially damaging threat to the operation of a commercial building.  In its less serious form, corrosion can produce problems ranging from lost heat transfer efficiency and constricted pipes – to annoyance pinhole leaks and temporary shutdowns. In extreme, but all too common examples, the failure to recognize and address a serious corrosion problem often results in a major pipe failure, loss of system services, high replacement costs, and legal liability.  For New York City properties, the age of the structure has a significant impact regarding pipe condition due to the various changes in construction and materials which have taken place over many decades. The age of a building property often defines the grade of pipe material used, it’s schedule or beginning wall thickness, corrosion susceptibility, and the general conditions under which natural deterioration has taken place.  Having provided piping evaluations at hundreds of commercial building properties throughout New York, we find that most piping systems can…

CT-06:   Piping Problems The Six Most Common Forms Of Corrosion Affecting HVAC And Process Piping Systems While the external signs can sometimes be subtle, learning of a corrosion problem often requires little more than a quick look into the cooling tower pans or related HVAC equipment such as refrigeration machines, pumps, and heat exchangers.  A rust build-up at the tower, fouled drift eliminators, tuberculation deposits, and flakes of scale and rust caught in the condenser water tubes are obvious indications of a corrosion problem.  Likewise, encrustations at the threaded joints, buckets of rust captured at start-up, a 10 MPY corrosion coupon result, lost heat transfer, and failed equipment should prompt the need to investigate further. Under real world conditions defined by the laws of nature, some degree of corrosion must be expected to exist within any piping system.  However, identifying the type and severity of corrosion responsible requires far more effort, and often multiple investigative tools.  The monitoring, testing, diagnosis, control, and repair of piping related corrosion problems is a multi-billion dollar business in itself.  Yet, corrosion caused piping replacement in the United States still exceeds…

CT-01:   Inadequate Corrosion Control Recognizing The True Threat Of Corrosion To Building Services Piping The severe corrosion of HVAC piping systems and their related equipment presents the most potentially damaging losses to any private, government, industrial, or commercial property next only to the threat of fire. It is surprising to see, therefore, the relatively low priority often provided for corrosion control and monitoring of critical HVAC and process piping by many building owners, operators, and plant engineers.  For many building properties, corrosion control is of little concern.  Whereas condenser and open water corrosion rates of 0.5 – 2 mils per year (MPY) were typical only three decades ago and easy to achieve, it is now common to find system-wide corrosion rates of 5 MPY and greater – with rates occasionally as high as 30 MPY. While certain unavoidable factors have contributed to generally higher corrosion rates, it remains clear that the service life of most piping systems could be greatly extended by allocating further effort to corrosion control measures. Massive Reporting Error A major factor in many pipe failures we see is caused by the often…

CT-05:   Microbiologically Influenced Corrosion The Greatest Threat To Any Condenser Water Or Open Process Cooling System Microbiologically Influenced Corrosion, commonly termed MIC, is a problem in many commercial and industrial properties simply due to the fact that microbiological communities are such common inhabitants of our environment.  MIC is most commonly found in open condenser water and process cooling loops, although its presence has been identified in most piping systems – from domestic water and fire sprinkler lines, to those serving hot water heating systems. For open systems, the main entry point for MIC is via the cooling tower – which provides the same function as a giant air scrubber by washing large quantities of particulates, organic material, and microbes into the water where it is then circulated throughout the piping system.  For closed systems, the microbes present in the make-up water usually provide the initial source of the problem.  Under favorable conditions, even a small initial contamination can produce significant end result. MIC based corrosion is extremely aggressive and in its worst form will lead to piping failures within a short period of time.  Once established,…

CT-04:   Internal Rust Deposits The Downward Spiral Of Greater Operating Problems For Every Piping System The interior of any HVAC piping system can show a wide range of corrosion characteristics – those characteristics and their severity being dependent primarily upon piping service, followed by physical orientation, age, pipe size, pipe quality, and location.  Steel, galvanized steel, cast iron, and ductile iron pipe produce substantially more deposits than the material which has been lost, which then causes restrictions to flow, possible thermal inefficiency, along with additional operating problems.  Brass and copper pipe, on the other hand, simply dissolve away. Corrosion problems do not appear overnight, and are generally the result of a failure to provide good chemical inhibitor protection and maintenance over an extended period of time.  While other factors and the failure to take certain preventative measures may also apply, high corrosion rates are very often related to the volume of rust deposits which have accumulated.  The volume of such deposits, and their ultimate impact, are in turn generally dependent upon the type of piping service involved.  While there are always exceptions, the following generalizations apply:…

CT-03:  Corrosion’s Added Impact Against Drained Pipe Proof That Annually Draining Down Condenser Water Piping Will Dramatically Increase Corrosion Rate Activity It is a generally recognized fact that fully drained or partially drained piping systems are far more susceptible to corrosion than those containing treated water, or even untreated water.  Given a moist environment in combination with the presence of abundant air and oxygen, partially drained pipe has been documented to corrode at a rate two to ten times that of other water filled pipe of the same type, and located within the same circulating system.  Condenser or open water systems clearly suffer the greatest in Northern climates where draining is often unavoidable. In cases where condenser water piping is drained down within the interior of a building to protect it from freezing, it is common to measure significantly higher corrosion rates at the rooftop or outside level.  In those cases, roof level piping will require replacement many decades before the remainder of the system.  The buckets of iron oxide and scale typically removed from strainers, condenser heads, and heat exchanger tubes at every spring start-up are partially…