Failure Analysis of Structural Systems and Components

Since 1947, Southwest Research Institute (SwRI) has been helping industry and government avoid the shutdowns and hazards associated with equipment and component failures. Using systematic failure analysis, SwRI isolates the causes of catastrophic failures and makes recommendations to prevent costly recurrences. Because SwRI neither manufactures nor endorses industrial products, investigations are impartial and unbiased, and client confidentiality is protected. Industries in which the Institute has specialized failure analysis expertise include:

• Power generation
• Aerospace
• Oil, gas, and chemical
• Manufacturing and transportation
• Medical

With 11 technical divisions and hundreds of fully equipped laboratories, SwRI uses a multidisciplinary approach to solve problems for major industries and small businesses alike.

Systematic Failure Analysis

SwRI investigators use systematic failure analysis to help industry and government:

• Identify design and process deficiencies
• Lower operating costs
• Improve safety
• Receive impartial evaluations
• Extend component service life

Power Generation

Fossil fuel, nuclear, and combined-cycle power companies use materials and structures under demanding environmental conditions for long periods of time. As the years of service increase, the possibility of failure grows.

SwRI has extensive experience conducting power plant investigations. Programs range from identifying the cause of boiler tube, complex compressor, and turbine component failures, to investigating radioactive components such as vent lines, pipes, and valves. This experience and an in-house radioactive materials laboratory make SwRI a leader in power industry failure analysis.

In the Institute's radioactive materials handling laboratory, failed radioactive components, materials, and equipment are investigated in accordance with radiation safety standards.

Aerospace

Investigation of failed, cracked, and damaged aerospace structures is crucial to the continued safe operation of the nation's aging fleet of civilian and military aircraft. Institute staff members are experts in identifying fatigue, a major failure mechanism in aircraft materials, and are schooled in manufacturing practices and codes relevant to military and commercial aircraft. SwRI methods allow early identification of cracking to provide a greater margin of safety and more accurately predict service life. Investigations have been conducted on commercial and military aircraft, including the C-5, F-5, F-16, F-111, T-37, and T-38. Components examined include forged bulkheads, landing gear, windshields, wing spars, spoilers, actuators, and engine turbine blades.

For life assessment studies, staff members perform fractography on critical aircraft structures, such as this wing spar, to identify crack initiation sites and growth rates.

Oil, Gas, and Chemical Industries

Producing, refining, and processing oil, gas, and chemical products degrade equipment that must operate in highly corrosive environments. Failure mechanisms include stress corrosion cracking, hydrogen sulfide attack, erosion-corrosion, fatigue, caustic attack, acid pitting, and hydrogen embrittlement. In addition to a laboratory dedicated to corrosion tests, SwRI has proven expertise in identifying and solving problems in the field. Past investigations have identified failures in rupture disks, heat exchangers, boiler tubes, drill collars, oil well tubing, pressure vessels, and steel and polymer pipelines for gas and liquids.

SwRI characterizes corrosion products and microstructures features to determine failure mechanisms, such as the internal corrosion shown in this hot water steel pipe.

Manufacturing and Transportation

The automobile, textile, and shipping industries fabricate products using both conventional and advanced manufacturing technologies. Failures can occur during manufacturing or while the product is in service. SwRI has conducted failure investigations for numerous product support and manufacturing operations, studying a wide variety of components and equipment, such as springs, pistons, forged parts, and conveyor systems.

SwRI characterized cracks in the storage tanks of this liquid natural gas tanker. After performing analyses, the Institute recommended repairs to extend the service life of the tanker.

Institute failure analysts investigate ways to improve product life with the latest technological developments. Examples include fuels and lubricants research and new coatings for improved lubrication and reduced wear. SwRI experts also refine fabrication practices, ranging from welding techniques for submersible pressure vessels to the superplastic forming of parts.

Scientists examined this paper mill bearing to determine if a catastrophic failure was caused by operating conditions or by a material flaw.

Medical Applications

Advances in medical equipment and biomedical technology have generated a variety of uses for common materials and new, biocompatible materials for equipment and implanted devices. The complex interactions of stress, friction, wear, and chemical attack that occur in the human body can cause material-related failure. Institute researchers investigate failure mechanisms in biomedical implants and medical equipment, such as wear and delamination in orthopedic service. In addition, the material, mechanical, and chemical properties of devices are characterized following long-term service.

The Institute conducts failure analyses of medical equipment, such as this catheter wire and needle used in a radiation therapy device.

Facilities

The Institute's modern laboratories are equipped to handle all aspects of failure analysis.

Instrumentation includes:

• Scanning electron microscopes for fractographic and metallographic analysis
• An X-ray diffraction system for deposit analysis
• Energy-dispersive X-ray systems to identify aggressive corrosion products
• A transmission electron microscope for fractographic and microstructural analysis
• A scanning auger microprobe to identify surface contaminants and microstructural phases
• Scanning tunneling and atomic force microscopes for nanoscale surface topography
• Metallographs for heat treat verification, microstructural examination, and material characterization
• A photographic laboratory to document investigations
• A portable microscope and hardness unit for field investigations
• Sixteen closed-loop, servo-hydraulically controlled mechanical test systems
• Autoclaves for high-pressure and high-temperature corrosion investigations

SwRI uses metallographs to determine crack morphologies, microstructural anomalies, and heat treatments. Here, a staff member examines the microstructure of a failed steel journal.

A scanning electron microscope coupled to energy-dispersive spectroscopic and image analysis systems determines fracture morphology, microstructural anomalies, and chemical compositions of failed components.

Facilities and laboratories are augmented by a network of computerized data acquisition and analysis equipment and a technical library containing more than 44,000 books and 55,000 volumes of periodicals.

Additional Services

The Institute models failure mechanisms, evaluates new designs, and assesses the effects of failure on operating systems using extensive analytical capabilities. To perform in-depth studies, SwRI applies:

• Finite element analysis
• Experimental stress analysis
• Damage tolerance analysis
• Life extension predictions
• Mechanical testing
• In-service condition assessment
• Hazard and risk assessment
• Failure modes and effects analysis
• Nondestructive evaluation

SwRI analyzes thermal and pressure stresses to determine what caused failure of a cracked stainless steel isolation valve from a nuclear power plant.

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