The conditions often producing a failure at outdoor located pipe also impact the pipe supports themselves.   With paint or a coating their only protection, the corrosion of pipe supports or structural steel relating to any cooling tower or piping system is simply a matter of inadequate maintenance. A minor and widely unrecognized impact to pipe also occurs due to the slightly different ground potential of the pipe in relationship to  the building steel.  Over decades, this small micro-volt difference can produce a galvanic type impact where both metals meet. A galvanic problem is also present for copper pipe held by steel pipe supports or hangers.  Whatever the source of the condition, weakened or failed pipe support no longer provide their intended function, and add new weight stresses to those still remaining.  For some systems such as domestic water, where pumps see intermittent use, support failure will allow the pipe to sway and water hammer with every cycle – thereby producing a stress to each joining clamp or thread. For insulated pipe where the insulation also covers  the pipe supports, an additional threat exists due to water entering and saturating the insulation – thereby creating a constant wet contact condition.

Photo Gallery I2:  Maintenance Required The most revealing indication to the care and maintenance that a building receives can be found by walking through its mechanical rooms.  While some properties maintain their refrigeration plant with almost the same level of care and dedication as they do their main lobby, most mechanical rooms provide evidence that the corrosion problems experienced should of come as no surprise.  Rusty water stains on the floor, moldy pipe insulation, multiple pipe repairs made of gasket material and hose clamps, and burnt out motors piled in the corner provide obvious indication that maintenance has been lacking. Given its obvious presence, a lack of maintenance is often tolerated at top management levels.  It may also be induced by a lack of maintenance funds, or by a work ethic favoring minimal effort.    Almost always, a maintenance deficiency is only addressed after some issue gains public and often critical notice. In one of the photographs below, meticulously painting around a 5 gallon pail likely took greater effort than moving it.  An example only outdistanced by finding a skeletonized dead cat in a mechanical room while conducting a UT investigation of the domestic water system, and being handed a…

Photo Gallery I1:  Cooling Tower Corrosion A corrosion problem at any condenser water system is likely to be first exposed by conditions at the cooling tower.  While some issues such as algae in the pans or tower fill does not necessarily indicate a corrosion problem, it does indicate a lower level of care and maintenance – from which a higher corrosion level may also result.  White scaling deposits covering the tower fill, side walls, and pans indicate its operation at excessive cycles of concentration.  Muddy or highly turbid water certainly indicate a higher than normal corrosion condition.  Pinholes through the pan, a far greater concern which is difficult to ignore. Open cooling tower systems have inherently higher corrosion levels than all other HVAC systems.  This is due to multiple factors discussed on this Internet site, with the most obvious issue being the far lower corrosion inhibitor levels maintained.  Removing buckets of rust and chip scale during start-up or during regular maintenance of the cooling tower should suggest some further investigation since that rust now ending up in the dumpster represents the building’s former pipe wall. Although most newer condenser water systems have water filtration installed, the overwhelming majority of filtration…

Photo Gallery F10:  Fire Sprinkler Valve Trim Pipe As is often the case, some of the smallest of issues have been responsible for the greatest failures and tragedies – such as the lack of a bolt washer to a jet aircraft’s engine, or an O-ring for the space shuttle.  For fire protection systems, accumulated corrosion product inside the steel pipe has the potential to reduce or stop all water flow through the fire sprinkler heads; rendering the entire system useless in a time of greatest need.  For that reason, regular inspections are required.  Yet often overlooked, far less corrosion product is required to alter the function of the main valve providing water into the system in the first place. For dry and pre-action fire systems, vastly complicated piping arrangements control the main water supply valve both to open and close.  This “trim” pipe is typically small diameter 3/8 in. or 1/4 in. schedule 40 threaded galvanized steel pipe.  Aside from its small inside diameter, the galvanized steel pipe used in its assembly is the same lower quality galvanized steel so quickly failing at the much larger main supply runs.  When the smaller trim pipe corrodes, however, only a small volume…

Photo Gallery F9:  Steam / Steam Condensate Corrosion at steam lines varies widely; its rate and aggressiveness being dependent upon many factors.  In fact, it is the steam condensate itself which produces most of the damage – leaving the original design of the system and its maintenance as the factors most responsible for long service.  High pressure steam usually suffers less impact due to steam condensate give its higher temperatures less favoring condensate creation.  Critically important steam traps, if not maintained and allowed to fail, will either blow steam and waste money, or more importantly – allow steam condensate to collect and potentially destroy the bottom of the pipe. Service life is significantly dependent upon the quality and corrosion resistance of the pipe, piping schedule, system design, and steam quality.  At the same time we have documented steam pipe from the late 1800s still at or above its original thickness specification, we have documented new 10 year old steam pipe with only 5 more years of service life left.  Given that corrosion activity is always greater for the steam condensate lines due to the presence of weak carbonic acid in the condensate, corrosion rates are typically 3 times higher –…

Photo Gallery F8:  Sanitary Waste / Vent Historically, sanitary waste and vent pipe systems have offered the longest service life of most building systems due to the installation of extra heavy (XH) bell and socket cast iron pipe.  Galvanized steel and galvanized wrought iron can be also found at many older properties; threaded in place from standard and even extra heavy pipe.  An average service life exceeding 85 years is common, with many systems lasting 100 years or longer.  Orientation has a significant bearing upon the level of corrosion occurring; the degree of pitch or grade for horizontal lines a major factor in their deterioration.  Since each bell and socket joint is made using rubber, cement, poured lead, oakum for older building properties, or some other material, there is always the potential for leaks. Although typically unpressurized, waste piping systems have the potential to fail catastrophically.  Cast iron pipe is centrifugally formed; retaining significant internal stresses as it cools that are held in place by the strength of its wall thickness.  Once one side of the pipe deteriorates more than the other, to a degree impossible to predict, the pipe can fracture or split longitudinally down its entire length, as…

Photo Gallery F7:  Galvanized Steel / Domestic Hot Water Service Galvanized steel pipe should never be used for any hot water service due to the reason that heat destroys the zinc protective finish.  Although the higher temperatures found at domestic hot water systems are mostly involved, accelerated deterioration can even be measured at galvanized steel run-out waste pipe serving kitchens and bathrooms.  Dishwasher discharges are especially damaging.  Highest deterioration is typically closest to the outlet of the hot water furnace or water heater simply due to the increased temperature, and lower at the furthermost extremes. For most older buildings were galvanized steel pipe has been installed for domestic cold water service, brass was installed for the hot water side due to this well known vulnerability.  However, certain cities and geographical areas such as Chicago and elsewhere specified galvanized steel pipe for hot water service, which has now resulted in widespread hot water system failures.  Our frequent visits to Chicago has suggested that most larger high rise apartments and condominiums have this problem, as well as much of the Chicago infrastructure.  A very common finding from any ultrasonic testing investigation of galvanized steel hot water pipe is to show significant pitting…

Photo Gallery F6:  Galvanized Steel / Domestic Cold Water Service Galvanized steel pipe has been widely installed for domestic cold water systems and has generally provided excellent service for over 125 years.  It was also commonly installed for sanitary waste, vent, and rain leader systems.  Our ultrasonic investigation relating to galvanized steel pipe installed in 1896 at one downtown New York City building property for domestic water service, only replaced a few years ago, remains our oldest example.  Since then many changes have occurred – mostly related to its deteriorating quality and greater corrosion susceptibility.  Whereas earlier examples of galvanized steel pipe had a layer of zinc protection so thick it could be carved with a knife, the zinc coating for today’s products are so thin they will often not even survive the groove rolling process.  Foreign pipe manufacturers appear to produce to lowest quality product, and with almost all pipe today ERW rather than seamless, zinc protection at the longitudinal seam adds another vulnerability. For older buildings constructed before about 1965, galvanized wrought iron pipe was often installed since the wrought iron provided a stronger bond to the zinc protective finish – substantially extending service life.  Our recent UT…

Photo Gallery G1:  Copper Pipe Corrosion Copper was once considered virtually immune to corrosion although that was never a valid assumption.  Service life estimates for domestic water service were generally at 65 years and greater.  But like most other piping materials, changes over the past two decades in the form of lower quality and higher corrosion resistance, undersized wall thickness, the greater use of water conditioning, and different system designs and joining methods have now added copper pipe to any building’s list of piping concerns.  Copper is also susceptible to deep galvanic cell pitting caused by rust particles migrating and settling on the copper pipe as a result of the upstream corrosion from steel and galvanized steel pipe or the steel hot water heater tubes. As a much softer metal, copper is vulnerable to higher water velocities and the erosion it causes – unlike carbon steel.  Changes in flow direction at elbows and tees are common failure points – a problem potentially accelerated with hex crimped joining methods.  Softened water and especially RO water further increases the threat of each of its vulnerabilities.  Where the copper pipe itself is providing good service, changes to the many brass valves, strainers, and…

Photo Gallery F5:  Dry / Pre-Action Fire Sprinkler Unquestionably, the most troublesome fire protection systems are of dry and pre-action type design for a multitude of reasons.  The common threat is due to the fact that they are “dry” in name only.  As soon as hydrostatic testing is performed, some water will remain to initiate higher corrosion activity.  Water remaining along the bottom and with abundant air and oxygen above it produces a far greater corrosion condition than if the pipe were completely filled with water and left stagnant.  With industry and government regulations mandating regular flow testing of such systems, new fresh oxygenated water is constantly introduced to replenish and advance high corrosion conditions.  The most common reaction to a failure of such fire sprinkler system is that it could not occur due to corrosion given that they are dry. Most such systems are not installed with an incline or grade to help remove the water, with the specified grade still inadequate to remove water even if applied.  The internal bump created by roll-grooving the pipe itself prevents full draining under anything except a steep vertical orientation.  As many of the below photographs prove, clearly defined water lines remain…