Authored by: Rimkus Forensics Marketing Team
Published 5/8/2026
In 2024, 213 workers in the United States were killed by being struck, caught, or compressed by running powered equipment, according to the Bureau of Labor Statistics fatal injury census. Behind many incidents is a question that insurance carriers, attorneys, and plant operators may seek to answer: what failed, and why?
Industrial equipment root cause analysis is the post-incident forensic investigation discipline that evaluates the physical, metallurgical, and mechanical evidence associated with a failed component. Forensic investigation begins after the loss has occurred, and its outputs may support insurance subrogation, product liability litigation, regulatory response, and recurrence prevention.
The sections below outline common failure modes, the step-by-step investigation process, laboratory methods, and the admissibility standards that may apply to forensic reporting.
Key Takeaways: How forensic equipment failure investigations work
Claims managers, litigation attorneys, and risk managers typically encounter forensic root cause analysis after a loss event triggers an investigation.
What distinguishes forensic root cause analysis
- Forensic investigation is retrospective and evidence-based; reliability engineering is prospective and statistical
- Investigations may reference standards addressing evidence collection, preservation, and chain of custody
- The causation framework generally distinguishes among proximate cause, contributing factors, and root cause
These distinctions may affect investigation scope and documentation.
How investigations typically proceed
- Non-destructive methods generally precede destructive testing to preserve evidentiary value
- Laboratory techniques may include fractography, metallography, electron microscopy, and mechanical testing
- Reports are typically prepared with Rule 702 admissibility considerations in mind
Together they may build the evidentiary foundation for causation opinions.
Rimkus provides forensic root cause analysis for industrial equipment failures across insurance and legal contexts: contact us to discuss requirements.
What is industrial equipment failure analysis, and how does it differ from reliability analysis?
Industrial equipment failure root cause analysis is a post-incident forensic investigation that uses the scientific method to evaluate why a piece of equipment failed, tracing the chain of events from the immediate trigger toward one or more underlying initiating causes. In insurance and litigation contexts, the discipline helps resolve disputes arising when a product or structure fails to perform as expected and a loss results.
Reliability analysis is prospective: it uses statistical models and operational data to predict the likelihood of future failures and inform maintenance scheduling. Forensic root cause analysis is retrospective: it begins after equipment has failed, and its primary purpose is typically causation determination suitable for use in legal and insurance proceedings rather than maintenance planning.
Why does post-failure analysis matter?
Insurance carriers may use forensic findings to evaluate subrogation potential, identify additional responsible parties, and set appropriate reserves. Attorneys often rely on forensic reports in product liability disputes, where distinctions among manufacturing defects, design defects, and misuse are often determinative for liability theories and damages models.
Plant operators and risk managers typically use findings to inform regulatory response (OSHA 1910.119 PSM incident reports, EPA Risk Management Plan filings) and to support recurrence prevention through revised maintenance procedures, training updates, or specification changes.
What equipment categories are most commonly investigated?
Forensic caseloads often involve several recurring equipment categories, each with characteristic failure modes that often inform the investigation methodology.
Pressure vessels and piping are commonly addressed in U.S. Chemical Safety Board (CSB) investigations. Common failure mechanisms include weld defects, hydrogen-induced cracking, internal corrosion under insulation, and overpressure events associated with relief device malfunctions. Investigations typically draw on ASME Section VIII fabrication records, weld procedure qualifications, and operating pressure histories.
Rotating equipment failures (turbines, compressors, pumps, gearboxes, fans) commonly involve bearing failures, shaft fatigue, blade liberation, misalignment, imbalance, and lubrication breakdown. Vibration data, oil analysis records, and trip histories are common inputs to the investigation.
Electrical equipment investigations arise primarily in fire and explosion causation, transformer failures, switchgear arcing events, and safety shutdown system malfunctions. Investigators typically request relay event records, fault current calculations, and protective device coordination studies.
Fluid power systems failures often involve seal degradation, fluid contamination, hose ruptures, and pressure spikes from valve malfunctions. These investigations are common in heavy industrial presses, mobile equipment, and aerospace ground support, where uncommanded motion can cause severe injury.
What are the common failure modes and root causes?
Forensic engineers often classify industrial equipment failures into recurring mechanism categories, including fatigue, fracture, corrosion, wear, and distortion. Each mode typically leaves distinct physical evidence visible at macroscopic, microscopic, and metallographic scales, and identifying which mechanism initiated the failure is often an early analytical step before tracing back to root causes. The four sections that follow describe the principal mechanisms, their characteristic signatures, and the conditions under which each typically arises.
Fatigue
Fatigue failures progress through crack initiation and propagation under cyclic loading. High-cycle fatigue is characterized by beach marks (concentric ridges on the fracture surface) and microscopic striations visible under scanning electron microscopy (SEM).
Low-cycle fatigue, occurring at higher stress amplitudes with fewer cycles, typically shows broader striations and more extensive plastic deformation. Thermal fatigue is associated with repeated heating and cooling cycles that impose cyclic thermal stress.
Fracture
Ductile fracture occurs by microvoid coalescence under single overload, typically yielding a dimpled fracture surface and significant macroscopic deformation. Brittle fracture may be characterized by relatively flat surfaces and chevron markings that can help identify the crack origin. Intergranular fracture, where grain boundaries separate, may show a “rock candy” appearance and can indicate mechanisms such as embrittlement, environmental attack, or other material-related conditions.
Corrosion
Uniform corrosion is associated with even material loss; pitting typically generates localized deep pits that frequently initiate fatigue cracks. Stress corrosion cracking (SCC) typically involves the simultaneous presence of a susceptible material, tensile stress, and a specific corrosive environment. Its branching crack morphology may help distinguish it from fatigue.
Wear and distortion
Adhesive wear transfers material between sliding surfaces; abrasive wear typically generates parallel grooves aligned with the direction of relative motion. Erosive wear is associated with repeated particle or fluid impingement.
Creep, a time-dependent deformation process often associated with elevated temperature, may be associated with grain boundary cavitation and measurable dimensional change.
How are equipment failures investigated step by step?
The investigation typically follows a sequence informed by industry standards, with non-destructive steps preceding destructive ones, and the applicable standards depend on jurisdiction, industry, and the specific failure context. The three subsections below describe the phases most investigations move through: scene response, visual examination, and sample collection with chain-of-custody documentation.
Site response and evidence preservation
Scene documentation typically precedes any disturbance of failed components. Standard practice calls for photographing, diagramming, and recording conditions before any component is moved. Perishable evidence, such as environmental conditions or fluid levels present at the time of failure, may change rapidly and is typically documented early. Fracture surfaces are typically left untouched and uncleaned to preserve microscopic evidence.
Modern industrial equipment often generates electronic records from programmable logic controllers, distributed control systems, and condition monitoring sensors. Capturing this digital evidence before maintenance crews replace components or restart production may preserve data that becomes important to later causation analysis.
Visual examination and documentation
Visual and low-magnification examination (typically 1x to 50x using stereomicroscopes with oblique lighting) may help identify fracture origins, crack paths, corrosion patterns, and deformation. Design specifications, fabrication records, and service history inform the examination. The component’s loading regime (cyclic versus steady-state), environmental exposure, and maintenance history often influence how visual findings are interpreted.
Sample collection and chain of custody
Chain of custody is the chronological record of the transfer, handling, and storage of an item from its point of collection to its final return or disposal. Documentation typically includes evidence descriptions, unique case identifiers, collection and storage locations, and records of transfer transactions. A broken chain of custody may be raised as grounds for challenging admissibility and any expert opinions resting on that evidence.
What analytical methods are used in root cause investigations?
Non-destructive testing, including ultrasonic, radiographic, magnetic particle, and liquid penetrant methods, may help document the full extent of cracking before sectioning. Fractography, the examination of fracture surfaces, may help identify crack origins, propagation directions, and failure mechanisms through macroscopic and SEM examination.
Chemical composition analysis may help confirm alloy identity. Optical metallography (microscopic examination of polished and etched cross-sections) and might reveal grain structure anomalies.
SEM with energy dispersive spectroscopy (EDS) can help resolve fracture features at sub-micron scale. Hardness and mechanical testing per ASTM E8/E8M and ASTM E18 may help quantify material properties against specifications.
Finite element analysis may help reconstruct stress distributions at the failure location. Laboratories often apply these methods in sequence to build the evidentiary record.
How forensic root cause analysis relates to FMEA, FMECA, and 5 Whys
These adjacent methodologies serve different purposes within the broader failure analysis discipline. Failure Mode and Effects Analysis (FMEA) and its related variant, Failure Mode, Effects, and Criticality Analysis (FMECA), are prospective tools governed by standards such as SAE J1739 and IEC 60812. Both are used during design or process review to anticipate how systems can fail and prioritize mitigations, sitting upstream of any actual incident. The 5 Whys technique is a structured questioning method commonly used in lean manufacturing, Six Sigma, and quality improvement programs to trace causal chains. Forensic root cause analysis differs from each: it begins only after a failure has occurred, synthesizes physical evidence, laboratory testing, document review, and witness accounts, and yields findings intended to meet evidentiary standards under Daubert and the Federal Rules of Evidence.
Causation determination
Causation determination typically applies a three-tier framework. The proximate cause is generally viewed as the legally relevant cause closely connected to the failure, which may or may not be the event occurring immediately before it. Contributing factors are conditions that may have contributed to the failure, whether or not they would have caused the failure independently. The root cause is typically viewed as the initiating event identified by repeatedly tracing the causal chain.
An investigation that identifies only the proximate cause, the mechanical trigger, may be inadequate for subrogation or product liability purposes. Tracing back to a root cause that may be associated with a specific party (manufacturer, installer, maintenance contractor, operator) is often what makes the report actionable.
Expert testimony and admissibility
Federal Rule of Evidence 702, amended December 1, 2023, requires that the proponent demonstrate by a preponderance of evidence that expert testimony rests on sufficient facts, reliable methods, and reliable application of those methods to the case. The amendment clarified that the proponent must show that the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.
Under the Daubert standard, as extended in Kumho Tire to non-scientific experts, forensic mechanical and electrical engineers offering causation opinions face the same reliability scrutiny as scientists. Standards can serve as evidence that the expert’s methodology has standards controlling its operation, addressing the third Daubert reliability factor. Experts who provide expert witness testimony in equipment failure disputes typically present both factual investigation findings and expert opinion on causation.
When physical evidence tells the story
Industrial equipment root cause analysis can help translate fractured components, corroded surfaces, and deformed structures into evidence-based causation opinions. The discipline’s value largely depends on evidence preserved in the first hours after a loss, chain-of-custody documentation maintained through laboratory analysis, and methodology that satisfies evolving admissibility standards. For claims managers evaluating subrogation potential, attorneys building or defending product liability cases, and risk managers responding to regulatory inquiries, the forensic investigation is often where technical answers begin to take shape.
For organizations seeking forensic investigation support, Rimkus offers Forensic Services backed by 40+ years of experience, 100+ offices worldwide, and 900+ experts on staff. Contact us to discuss specific requirements.
Frequently asked questions about industrial equipment failure analysis
How do forensic engineers determine whether equipment failure was caused by a manufacturing defect, design defect, or misuse?
Forensic engineers evaluate the failed component against its specifications, design requirements, service history, and operating conditions. Manufacturing defects may appear as deviations from specification, such as incorrect alloy, improper heat treatment, or fabrication anomalies. Design defects may be considered when a correctly manufactured component fails under foreseeable operating conditions. Misuse analysis examines whether maintenance records, operator logs, and physical evidence indicate operation outside the design envelope.
How does fault tree analysis (FTA) help investigate complex equipment failures?
Fault tree analysis is a deductive framework that works backward from a defined failure event to identify possible contributing pathways. In forensic equipment failure investigations, it may help test alternative hypotheses, identify single-point vulnerabilities, and show how multiple conditions may have combined to produce the failure.
This article is intended to provide general information and insights into prevailing industry practices. It is not intended to constitute, and should not be relied upon as, legal, technical, or professional advice. The content does not replace consultation with a qualified expert or professional regarding the specific facts and circumstances of any particular matter.