Photo Gallery of Piping Failures

     We offer below a series of examples of different piping failures taken from years of archival ultrasonic pipe testing and inspection work. Such failures are unfortunately a common finding for many of our investigations, and often ignored.

     Usually, piping failures are the result of a corrosion problem allowed to continue unaddressed. Sometimes, however, they are due to engineering design - such as the use of thin wall pipe, cut grooved piping, or due to faulty assembly and construction methods. Reliance on corrosion coupons, commonly found to under report true corrosion activity at the pipe itself by a factor of 10 times or more,

     In many examples, an initial failure at some location, such as at a threaded joint or weld, will signal a more system wide threat due to the same reason. In such cases, a metallurgical examination, whereby the pipe is sectioned in half to precisely identify the problem cause, is the correct line of investigation to follow.


Multiple Causes - This 11 year old sample of 2-1/2 in. condenser water pipe failed at the threads due to a combination of galvanic activity at the steel to brass valve connection and a basic design flaw. The use of threaded schedule 40 steel pipe for condenser water use was an even greater factor - with over 50% of wall lost due to threading, and only 35 mils or 0.035 in. remaining in that area.		Total Failure - This extraordinary photo shows a completely failed threaded nipple at a 24 in. main condenser water return riser. Accumulation of interior deposits at the valve first clogged the 1 in. nipple completely. Then, a combination of general and galvanic corrosion caused its failure and total separation - leaving those rust deposits to alone hold back 15 upper floors of water. Amazing that it held!


Dry Sprinkler - Top and bottom view of dry fire sprinkler pipe showing virtually new pipe on the top at left, and severely corroded bottom pipe on the right. Water remaining at the bottom after pressure testing typically creates accelerated wall loss along the bottom area and lower sides. Pinholes are typically the first indication of a problem, followed by a general and complete failure of the entire system.		Thread Failure - This is an extremely common problem due to the use of thin wall schedule 40 pipe in open water condenser or process cooling piping applications. While larger diameter main riser and distribution lines can be constructed of schedule 40 pipe in most applications, schedule 40 for small diameter run-out lines will not provide sufficient remaining wall thickness and acceptable service life.


Mold - A combination of poorly insulated chill water pipe and an excessive humidity condition combined to create a serious mold problem throughout this entire area. While UT testing showed the corrosive moisture effect against the steel pipe as surprisingly minimal, mold had thoroughly contaminated the entire area, creating a health threat. All ceilings had to be opened, the insulation removed, the pipe scraped and coated to prevent further rusting, and heavier insulation properly applied.		Pinhole Leak - This 4 in. schedule 40 condenser water system produced fine pinhole leaks after less than 4 years of service. Ultrasonic testing showed a generally high corrosion rate of over 15 MPY, with random and isolated areas showing excessive corrosion rates exceeding 50 MPY. Areas of pipe showed 0.075 in. remaining, and further pinholes imminent. The loss of 0.237 in. of pipe wall for this size pipe itself defines a corrosion rate exceeding 60 MPY - for which no piping system can survive.


Cut Grooving - Cutting the groove into pipe rather than swaging it removes substantial wall thickness, and creates an immediate weakness at the pipe joint. Where a corrosion problem exists, the grooved area then is most vulnerable, and will inevitably fail first. The cut groove loss of 0.125 in. in pipe wall at 12 in. condenser water pipe represents an immediate loss of 30 years of service assuming a moderate corrosion rate of 4 MPY.		Dezincification - Typical surface deposit resulting from the dezincification of brass pipe due to old age and/or an aggressive water condition. Over many years, the zinc component of the metal is leached out to leave copper. Deep pitting is initiated and the pipe becomes porous prior to producing an actual leak, and leaving a corrosion product behind.


Extremely High Corrosion - A high corrosion rate of near 15 MPY destroyed this new piping installation in under 2 years. This client was in the process of replacing 15 floors of threaded 2 in. distribution piping beginning at the bottom floors and working upward. Performed halfway through the project, ultrasonic testing showed that the new pipe would fail before pipe replacement would be completed.		Internal Deposits - Corrosion of steel pipe results in iron oxide deposits of approximately 19 times the volume of the steel lost. The presence of internal deposits therefore defines a corrosion problem, and vice versa. For the above domestic cold water pipe, loss of water flow due to internal constriction was actually the lesser threat. Wall loss at the threads had reached the point of failure.


	Cut Grooving - Victaulic and other brand groove clamped piping systems offer substantial advantages in piping construction. Rolling or swagging the groove into the pipe simply displaces the metal inside, and therefore no wall loss results. Cutting the groove, however, a sometimes used option, significantly lessens available wall thickness, and if combined with a higher corrosion rate - will lead to advanced joint failure.		Thread Failure - Six years of service under a 6 MPY corrosion rate left this schedule 40 condenser water piping system with only 33 mils or 0.033 in. of pipe wall remaining at the threads - therefore the leaks seen. Under normal corrosion conditions of 1-2 MPY, and using heavier schedule 80 pipe, this pipe would last for decades. However, its failure, prior to any shut off valve, required draining of the entire system for replacement.


Maintenance Neglect - This roof level pipe near the cooling tower suffered both from the outdoor elements and a constant over spray from the cooling tower itself. The pipe showed sufficient exterior pitting to reduce its remaining overall wall thickness to approximately 0.130 in., requiring placement.		Weld Failure - A relatively uncommon problem due to either inappropriate welding rod use or poor workmanship. This mechanical defect is often made worse by a high corrosion rate and can only be repaired by grinding away the weld and rewelding it properly, or by total replacement.


Weld Failure - Generally, a single leak of failure problem may be attributed to a random and isolated event. Further examples usually suggest a more system wide defect with much greater threat potential. For welding failures such as above, and other mechanical questions, metallurgical testing and ultrasonic flaw detection are the two main diagnostic tools available.		Pipe Repair? - Most often, pipe problems remain hidden until the first leak brings it to attention and further diagnosis and repairs are quickly made. Then again, some repairs are postponed, and postponed until no alternative remains - actions which always increase the potential for significant damage, the need for shutdown, and usually overall cost.


Waste Line Failure - This is a fairly typical form of failure at cast iron waste lines. Cast iron lines corrode at wildly varying rates at top and bottom of the pipe, and at horizontal vs. vertical lines. Moisture alone is especially destructive to cast iron. UT testing at cast pipe is difficult due to the inherent porosity of the material, and due to its varying corrosion characteristics.		Cast Pipe - Another example showing the typical corrosion characteristics of cast iron pipe. This 75 year old cast iron pipe had multiple leak clamps applied to its top surface but showed acceptable wall thickness elsewhere. Wall thickness at the bottom was not far below specification - yet the top was obviously beyond service.


	Tank Corrosion - Steel domestic water tanks often suffer from a combination of internal and external corrosion, as shown here. Interior protective coatings can fail in areas, which allows deep pitting activity. In addition, the cold inlet water often produces condensation at the tank exterior, and corrosion where the coating has weakened. A lack of maintenance is the obvious cause, more so than a corrosion problem.		Hidden Corrosion - Discoloration of piping insulation is always a strong sign that a leak is underway. In many cases, this may be attributed to condensation, though unlikely. Fiberglass insulation can absorb a substantial amount of water, more if jacketed and painted, and can allow a pinhole problem the time necessary to develop into a more serious threat.


Under Deposit Corrosion - This extreme case of under deposit corrosion resulted in the total penetration of some areas of 12 in. schedule 40 pipe in under 10 years. Shown here is the very beginning of a pipe failure. Ultrasonic testing showed thickness values of under 0.100 in. in some areas, with other areas at near factory new thickness specification of 0.406 in. The removal of the pipe showed that high volumes of iron oxide deposits along the bottom of the pipe were the cause.		Contractor Error? - These two adjacent samples of 12 in. pipe were taken from the same condenser water system. Comparison of wall thickness in areas of little deposit and corrosion showed it as schedule 40 on the left, and schedule 20 on the right. Examples of schedule 20 substitution were found throughout. Compounding the problem is the under deposit corrosion present - which is more threatening to the schedule 20 pipe.


Replacement Due - Secondary equipment can often show corrosion problems far sooner than the actual piping itself. This centrifugal separator had three leaks beginning, while none were found at the main piping. With an original wall thickness of only 0.100 in. the pitting in this system reached through this metal wall sooner than the 0.280 in. of the 6 in. condenser water pipe.		Weld Failure - Multiple causes always exist for explaining problems at a pipe weld, and usually require a close metallurgical examination to provide a reliable answer. Improper cleaning or joint preparation, lack of weld penetration, incorrect rod selection, or just poor workmanship can all produce the same result. Multiple examples of the same deposits are sure sign that faulty welds exist.


Pinhole Leaks - An aggressive pitting condition usually spells disaster for any piping system. Here, a reliance on temporary pipe clamps produced a virtual lawn sprinkler system at this section of condenser water piping. Where one pinhole leak might be assumed to be an isolated case possibly related to a material defect or very localized condition, multiple leaks demand prompt attention and usually replacement.		Missing Insulation - A lack of insulation can often produce even worse piping damage at cold water piping than an excessive internal corrosion condition. Such corrosion activity is often random and very difficult to predict. It is largely dependent upon area humidity, surface temperature, as well as the natural corrosion susceptibility of the pipe itself. Exterior corrosion is often too severe to permit any nondestructive testing.


Insulation Failure - Here, breaks in the hard outer insulation covering allowed water and moisture to enter. Saturating the insulation with water substantially deteriorated the pipe's outer surface. Ultrasonic testing showed that the pipe wall had been reduced to below acceptable minimum levels and that replacement of those exterior pitted sections of pipe was required. The degree of exterior corrosion and hidden water damage also destroyed the electrical heat tracing cable - a fact previously unknown.		Pinhole Leaks - This relatively new piping system showed multiple pinhole leaks due to a severe pitting condition at its interior. In many cases, a growth or encrustation of rust deposits will seem to appear to grow at the pipe's outer surface. This is actually due to a microfine pinhole leak. In such examples, the rate of evaporation exceeds the rate of the leak - which them produces the deposit made up of formerly dissolved iron and minerals which have precipitated out at the pipe's outer surface.


Galvanizing Failure - A severe internal pitting condition at this domestic water line produce near total failure after approximately 12 years of service. Wet insulation suggested a corrosion under insulation condition, but the pipe had become nearly porous in some areas due to severe pitting.		Localized Pitting - Deep internal pitting exposed at galvanized domestic water pipe. Cross section of soon to fail area revealed by ultrasonic testing illustrates the depth of wall loss at this 6 in. pipe. Less the thread cut, failure was certain.


Thread Failure - A not so uncommon finding for domestic water galvanized steel piping. This photo well shows the damage caused to the threads by a combination of an aggressive domestic water supply and old age of 70 years. Internal pressure is always a major factor in advancing any threaded joint leak. This failure released the contents of a 5,000 gal water storage tank on the roof. Any galvanized steel pipe serving domestic service, and over 75 years of age, should be considered for replacement.		Groove Clamped Failure - Cutting the groove into the pipe exterior rather than rolling it is difficult to detect from the outside. The clamping method only becomes a threat to the piping system after a high corrosion condition has been established and the deterioration of the interior pipe wall nears that groove. Where a corrosion problem is suspected, effort should be always made to determine the method of grooving the pipe.


Dielectric Fittings - Dielectric or galvanic fittings are always recommended between any carbon steel to brass or copper fixture as shown above. While typically specified by most consulting and design engineers, dielectric fittings are rarely found in actual use - leading to significant losses at the threads over time and usually producing premature failure.		Schedule 10 Pipe - The recent trend to utilize thin wall schedule 10 pipe in fire sprinkler, condenser and process water applications has produced disastrous results in most examples. This pipe offers approximately half the initial wall thickness of previously considered thin wall schedule 40 pipe. Under even a moderate 3-4 MPY corrosion rate, most piping will fail within 10 years.


Deep Pitting - Various examples of exterior rust product at this fire sprinkler line suggested a failure at the threads. However, testing showed a system wide deep pitting condition primarily at the bottom of the pipe to be the cause of the leaks. Leaks at the threads had not occurred first simply due to the randomness of the pitting condition not existing in that area.		Insulation Failure - Failure of pipe insulation, especially at underground installations such as here, can easily produce dramatic corrosion rates of 50 MPY or more. Testing of pipe where the insulation held showed wall thickness readings at specification for this hot water piping after 25 years of service. In this example, outer corrosion penetrated 0.375 in. of thickness in the same time.

© Copyright