Principia’s engineering staff have investigated hundreds of failures covering plumbing, HVAC, process piping and fire protection systems. This includes construction defect investigations, pipeline explosions and industrial accidents.
Principia’s services include failure analysis and material testing, and on-site system testing. Principia has experience conducting materials tests such as tensile, shear and fatigue strength, tensile and flexural modulus, and residual stress. Our staff has conducted tests according to national and international standards such as the American Society for Testing and Materials (ASTM) and The International Standards Organization (ISO), as well as more abstract tests requiring special loading and custom setup.
Our staff has experience performing tests in the field. These are usually conducted to measure system performance or loads. Standard instruments are used, but often require non-standard installation techniques. HVAC and other piping systems and plumbing fixtures are not installed with ease of testing in mind. Often access is restricted, and sensor installation is limited to a very small area.
Laboratory fatigue testing of a soldered copper fitting was done to predict the damage caused over time by a recurring water hammer condition in a commercial plumbing system, and to compare it with damage that might occur suddenly such as that seen in over-pressure failure.
In comparison to axial fatigue, this fish-mouth appearance is the result of an over-pressure burst.
A section of 1/2 inch diameter PEX or cross-linked polyethylene pipe has suffered a leak. Was the material defective or was the pipe simply installed incorrectly?
The result of one of the material tests shows that the test pipe bursts at a very high pressure, suffering significant deformation.
Principia’s engineers are familiar with the latest material and installation standards as well as their historical versions and various changes over the years. It is common for installation guidelines to change with time as materials technology advances and understanding of system loads evolves. For example, the requirements for the installation of water heaters in California has changed many times in the past few years because of the lessons learned in the two most recent California earthquakes.
We provide accurate predictions of the performance and lifetime of HVAC and piping systems and plumbing fixtures with knowledge of a combination of material test results and understanding of the service conditions and loading. These predictions are invaluable in answering the question, “Why didn’t this product last as long as it was supposed to?” Understanding of the external loads often comes from our experience in the field. We have examined hundreds of failed systems including those where the loads came from ground movement.
These cast iron drain and vent pipes have pulled apart at their fittings because of ground settlement below a concrete slab.
A tile curb in a shower enclosure has suffered from cracking.
The crack showed little evidence of deterioration, suggesting that the loading that caused the damage occurred rapidly, likely as a result of an earthquake that had recently occurred.
Reduced performance or life can occur to piping systems as a result of corrosion or corrosion related damage. The corrosion can start from the inside and progress outward through the wall thickness, or start from the outside and work its way inward. Some amount of corrosion can be tolerated by most piping systems, but when the level of corrosion reduces the strength of the pipe to below the applied load, failure and leakage can occur.
The staff at Principia is trained to inspect the damage then quickly assess the specific analysis and/or testing necessary to efficiently establish the root cause – was the corrosion rate too high, or was the corrosion normal and the applied loads just higher than expected?
This section of cast iron pipe had suffered from exterior corrosion.
Often we are asked to determine how long the corrosion has been progressing.
This copper pipe fitting was still in service with a pinhole leak. The fitting was removed and then cut open. Pitting corrosion had started on the interior surface and progressed through the entire wall thickness. This fitting had been in service for only a short period of time. Locally aggressive water was the likely culprit.
Principia’s engineers have published several articles in the area of refrigeration and air conditioning failure analysis. We are often called to investigate damage to property or equipment that defies conventional approaches such as simple visual examination.
Principia’s engineers are trained to gather evidence for further detailed laboratory examination and testing, such as materials identification with Fourier transform infrared spectroscopy or x-ray energy dispersive spectroscopy.
Failures very early in the life of a mechanical system are often mitigated with a warranty. Principia engineers assist customers and vendors by finding the root cause of the failure, then working backward to its initiation. Customers are eager to find out if their installation and operation were outside of the limits, and vendors are eager to determine if a design or manufacturing defect exists.
Fixture leaks can make floors slippery, causing slips and falls. Principia’s engineers have the training and practical experience to locate leaks and their sources. This can involve pressure and flow testing as well as floor level surveys to trace water trails.
This is a commercial building bathroom where an employee of one of the tenants slipped and fell on a wet tile floor.
Principia’s engineers have extensive experience running tests in the field to quickly locate the source of the leak and with understanding of fundamental fluid flow determine the amount and location of collected water.
The performance of different materials can vary when subjected to the exact same load or displacement. Steel, aluminum and other common metals exhibit significant deformation before they fail. All materials exhibit characteristic features at the point of failure (fracture surface), but the features that might suggest progressive damage for one material may be characteristic of a one-time overload failure on another. Polymers too may readily deform when subjected to high loads, but may be sensitive to the speed at which the load is applied. Composite materials have found their way into common use in pipelines. Their unique characteristics require specific training and experience on the part of the investigator to find the root cause of failures.
Principia has this training and experience. Our staff has a combined 35 years of experience examining failures of various types of composite materials such as graphite epoxy and the more commonly used fiberglass and reinforced plastic mortar used in pipeline applications. We have specific training in the design, manufacture, testing and analysis of composite structures. We have authored several papers on the subject of composite materials for the American Society for Testing and Materials (ASTM), the International Society for the Advancement of Material and Process Engineering (SAMPE), and Composites Fabrication Magazine.
This section of fiberglass composite pipe has a rather large hole. The hole was caused by external loading.
Fire sprinklers are designed to release when subjected to a preset temperature during a fire. Sometimes they release inadvertently in the absence of a fire. The only evidence that often remains is the fire sprinkler body – the triggering device is rarely found after a release. Principia’s engineers learn valuable information regarding the system loads from examining the remaining parts. External loads are applied during installation and removal of the head. They may also suffer from impact damage during their life.
Principia’s engineers have training and experience to help differentiate between these different types of loading. Defects in the trigger mechanism can occur and often require careful examination to detect. Defects in the piping system can also lead to leaks. Principia’s engineers are experienced fractographers and metallographers who can detect flaws, determine the root cause of the leak, and present their findings using the most up-to-date methods.
An older fire sprinkler adjacent to a sprinkler which inadvertently released.
The fusible link shows signs of significant cracking probably from a damage mechanism called creep where materials with melting points relatively close to their duty temperature slowly deform under load over long periods of time.
Sometimes sprinklers will suffer an inadvertent release. The trigger mechanism for this sprinkler was the glass bulb design. Deformation to the sprinkler cage suggests that the sprinkler was subjected to relatively high loads (higher than those normally anticipated such as from pressure, assembly, or handling/shipping).
Detailed examination of the sprinkler is necessary to determine if the damage was simply the result of sprinkler removal after the release or if it indicates the cause of the failure.
Many industrial processes make extensive use of piping systems. These systems can be rather unique since they are often custom designed for the specific industry or even the specific location. Oil refineries, water and wastewater treatment plants, and chemical plants are examples of facilities which use significant amounts of process piping.
Principia’s engineers have investigated accidents at many varied industries. They are familiar with the fundamentals of piping systems used either for product delivery or monitoring and control.
Strain gage testing of a section of stainless steel process piping was performed to determine the level of residual stresses in the pipe wall that were caused as a result of manufacturing processes, and to predict what effect the residual stresses might have on the expected life of the pipe.
Principia’s engineers have experience in the investigation of failures of large-scale municipal piping systems including pumping and power generation stations. These range from penstocks for the delivery of water to hydroelectric power generation facilities to sewage pumping stations. All systems have in common the fundamentals of liquid transport; however, each type of system has its own unique characteristics.
For example, the pressure levels achieved in water transmission are much higher than that for gravity sewage; thus the design constraints for sewer pipe are typically dictated by soil overburden load compared to the pressure load associated with water pipe.
Mold needs water to grow. After mold has been discovered in a residence or commercial building, the task of identifying the possible sources of water begins. Among the possible sources are the domestic water supply, the drain, waste, vent system, the storm drainage, and the HVAC supply, return, and condensate lines.
We are experienced at inspecting, evaluating and testing these systems to determine if they are or have been leaking, and how long the leaking has been going on.